subscriptioncmds.c

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/*-------------------------------------------------------------------------
 *
 * subscriptioncmds.c
 *      subscription catalog manipulation functions
 *
 * Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * IDENTIFICATION
 *      src/backend/commands/subscriptioncmds.c
 *
 *-------------------------------------------------------------------------
 */
 
#include "postgres.h"
 
#include "access/commit_ts.h"
#include "access/htup_details.h"
#include "access/table.h"
#include "access/twophase.h"
#include "access/xact.h"
#include "catalog/catalog.h"
#include "catalog/dependency.h"
#include "catalog/indexing.h"
#include "catalog/namespace.h"
#include "catalog/objectaccess.h"
#include "catalog/objectaddress.h"
#include "catalog/pg_authid_d.h"
#include "catalog/pg_database_d.h"
#include "catalog/pg_foreign_server.h"
#include "catalog/pg_subscription.h"
#include "catalog/pg_subscription_rel.h"
#include "catalog/pg_type.h"
#include "catalog/pg_user_mapping.h"
#include "commands/defrem.h"
#include "commands/event_trigger.h"
#include "commands/subscriptioncmds.h"
#include "executor/executor.h"
#include "foreign/foreign.h"
#include "miscadmin.h"
#include "nodes/makefuncs.h"
#include "pgstat.h"
#include "replication/logicallauncher.h"
#include "replication/logicalworker.h"
#include "replication/origin.h"
#include "replication/slot.h"
#include "replication/walreceiver.h"
#include "replication/walsender.h"
#include "replication/worker_internal.h"
#include "storage/lmgr.h"
#include "utils/acl.h"
#include "utils/builtins.h"
#include "utils/guc.h"
#include "utils/lsyscache.h"
#include "utils/memutils.h"
#include "utils/pg_lsn.h"
#include "utils/syscache.h"
 
/*
 * Options that can be specified by the user in CREATE/ALTER SUBSCRIPTION
 * command.
 */
#define SUBOPT_CONNECT              0x00000001
#define SUBOPT_ENABLED              0x00000002
#define SUBOPT_CREATE_SLOT          0x00000004
#define SUBOPT_SLOT_NAME            0x00000008
#define SUBOPT_COPY_DATA            0x00000010
#define SUBOPT_SYNCHRONOUS_COMMIT   0x00000020
#define SUBOPT_REFRESH              0x00000040
#define SUBOPT_BINARY               0x00000080
#define SUBOPT_STREAMING            0x00000100
#define SUBOPT_TWOPHASE_COMMIT      0x00000200
#define SUBOPT_DISABLE_ON_ERR       0x00000400
#define SUBOPT_PASSWORD_REQUIRED    0x00000800
#define SUBOPT_RUN_AS_OWNER         0x00001000
#define SUBOPT_FAILOVER             0x00002000
#define SUBOPT_RETAIN_DEAD_TUPLES   0x00004000
#define SUBOPT_MAX_RETENTION_DURATION   0x00008000
#define SUBOPT_WAL_RECEIVER_TIMEOUT         0x00010000
#define SUBOPT_LSN                  0x00020000
#define SUBOPT_ORIGIN               0x00040000
 
/* check if the 'val' has 'bits' set */
#define IsSet(val, bits)  (((val) & (bits)) == (bits))
 
/*
 * Structure to hold a bitmap representing the user-provided CREATE/ALTER
 * SUBSCRIPTION command options and the parsed/default values of each of them.
 */
typedef struct SubOpts
{
    uint32      specified_opts;
    char       *slot_name;
    char       *synchronous_commit;
    bool        connect;
    bool        enabled;
    bool        create_slot;
    bool        copy_data;
    bool        refresh;
    bool        binary;
    char        streaming;
    bool        twophase;
    bool        disableonerr;
    bool        passwordrequired;
    bool        runasowner;
    bool        failover;
    bool        retaindeadtuples;
    int32       maxretention;
    char       *origin;
    XLogRecPtr  lsn;
    char       *wal_receiver_timeout;
} SubOpts;
 
/*
 * PublicationRelKind represents a relation included in a publication.
 * It stores the schema-qualified relation name (rv) and its kind (relkind).
 */
typedef struct PublicationRelKind
{
    RangeVar   *rv;
    char        relkind;
} PublicationRelKind;
 
static List *fetch_relation_list(WalReceiverConn *wrconn, List *publications);
static void check_publications_origin_tables(WalReceiverConn *wrconn,
                                             List *publications, bool copydata,
                                             bool retain_dead_tuples,
                                             char *origin,
                                             Oid *subrel_local_oids,
                                             int subrel_count, char *subname);
static void check_publications_origin_sequences(WalReceiverConn *wrconn,
                                                List *publications,
                                                bool copydata, char *origin,
                                                Oid *subrel_local_oids,
                                                int subrel_count,
                                                char *subname);
static void check_pub_dead_tuple_retention(WalReceiverConn *wrconn);
static void check_duplicates_in_publist(List *publist, Datum *datums);
static List *merge_publications(List *oldpublist, List *newpublist, bool addpub, const char *subname);
static void ReportSlotConnectionError(List *rstates, Oid subid, char *slotname, char *err);
static void CheckAlterSubOption(Subscription *sub, const char *option,
                                bool slot_needs_update, bool isTopLevel);
 
 
/*
 * Common option parsing function for CREATE and ALTER SUBSCRIPTION commands.
 *
 * Since not all options can be specified in both commands, this function
 * will report an error if mutually exclusive options are specified.
 */
static void
parse_subscription_options(ParseState *pstate, List *stmt_options,
                           uint32 supported_opts, SubOpts *opts)
{
    ListCell   *lc;
 
    /* Start out with cleared opts. */
    memset(opts, 0, sizeof(SubOpts));
 
    /* caller must expect some option */
    Assert(supported_opts != 0);
 
    /* If connect option is supported, these others also need to be. */
    Assert(!IsSet(supported_opts, SUBOPT_CONNECT) ||
           IsSet(supported_opts, SUBOPT_ENABLED | SUBOPT_CREATE_SLOT |
                 SUBOPT_COPY_DATA));
 
    /* Set default values for the supported options. */
    if (IsSet(supported_opts, SUBOPT_CONNECT))
        opts->connect = true;
    if (IsSet(supported_opts, SUBOPT_ENABLED))
        opts->enabled = true;
    if (IsSet(supported_opts, SUBOPT_CREATE_SLOT))
        opts->create_slot = true;
    if (IsSet(supported_opts, SUBOPT_COPY_DATA))
        opts->copy_data = true;
    if (IsSet(supported_opts, SUBOPT_REFRESH))
        opts->refresh = true;
    if (IsSet(supported_opts, SUBOPT_BINARY))
        opts->binary = false;
    if (IsSet(supported_opts, SUBOPT_STREAMING))
        opts->streaming = LOGICALREP_STREAM_PARALLEL;
    if (IsSet(supported_opts, SUBOPT_TWOPHASE_COMMIT))
        opts->twophase = false;
    if (IsSet(supported_opts, SUBOPT_DISABLE_ON_ERR))
        opts->disableonerr = false;
    if (IsSet(supported_opts, SUBOPT_PASSWORD_REQUIRED))
        opts->passwordrequired = true;
    if (IsSet(supported_opts, SUBOPT_RUN_AS_OWNER))
        opts->runasowner = false;
    if (IsSet(supported_opts, SUBOPT_FAILOVER))
        opts->failover = false;
    if (IsSet(supported_opts, SUBOPT_RETAIN_DEAD_TUPLES))
        opts->retaindeadtuples = false;
    if (IsSet(supported_opts, SUBOPT_MAX_RETENTION_DURATION))
        opts->maxretention = 0;
    if (IsSet(supported_opts, SUBOPT_ORIGIN))
        opts->origin = pstrdup(LOGICALREP_ORIGIN_ANY);
 
    /* Parse options */
    foreach(lc, stmt_options)
    {
        DefElem    *defel = (DefElem *) lfirst(lc);
 
        if (IsSet(supported_opts, SUBOPT_CONNECT) &&
            strcmp(defel->defname, "connect") == 0)
        {
            if (IsSet(opts->specified_opts, SUBOPT_CONNECT))
                errorConflictingDefElem(defel, pstate);
 
            opts->specified_opts |= SUBOPT_CONNECT;
            opts->connect = defGetBoolean(defel);
        }
        else if (IsSet(supported_opts, SUBOPT_ENABLED) &&
                 strcmp(defel->defname, "enabled") == 0)
        {
            if (IsSet(opts->specified_opts, SUBOPT_ENABLED))
                errorConflictingDefElem(defel, pstate);
 
            opts->specified_opts |= SUBOPT_ENABLED;
            opts->enabled = defGetBoolean(defel);
        }
        else if (IsSet(supported_opts, SUBOPT_CREATE_SLOT) &&
                 strcmp(defel->defname, "create_slot") == 0)
        {
            if (IsSet(opts->specified_opts, SUBOPT_CREATE_SLOT))
                errorConflictingDefElem(defel, pstate);
 
            opts->specified_opts |= SUBOPT_CREATE_SLOT;
            opts->create_slot = defGetBoolean(defel);
        }
        else if (IsSet(supported_opts, SUBOPT_SLOT_NAME) &&
                 strcmp(defel->defname, "slot_name") == 0)
        {
            if (IsSet(opts->specified_opts, SUBOPT_SLOT_NAME))
                errorConflictingDefElem(defel, pstate);
 
            opts->specified_opts |= SUBOPT_SLOT_NAME;
            opts->slot_name = defGetString(defel);
 
            /* Setting slot_name = NONE is treated as no slot name. */
            if (strcmp(opts->slot_name, "none") == 0)
                opts->slot_name = NULL;
            else
                ReplicationSlotValidateName(opts->slot_name, false, ERROR);
        }
        else if (IsSet(supported_opts, SUBOPT_COPY_DATA) &&
                 strcmp(defel->defname, "copy_data") == 0)
        {
            if (IsSet(opts->specified_opts, SUBOPT_COPY_DATA))
                errorConflictingDefElem(defel, pstate);
 
            opts->specified_opts |= SUBOPT_COPY_DATA;
            opts->copy_data = defGetBoolean(defel);
        }
        else if (IsSet(supported_opts, SUBOPT_SYNCHRONOUS_COMMIT) &&
                 strcmp(defel->defname, "synchronous_commit") == 0)
        {
            if (IsSet(opts->specified_opts, SUBOPT_SYNCHRONOUS_COMMIT))
                errorConflictingDefElem(defel, pstate);
 
            opts->specified_opts |= SUBOPT_SYNCHRONOUS_COMMIT;
            opts->synchronous_commit = defGetString(defel);
 
            /* Test if the given value is valid for synchronous_commit GUC. */
            (void) set_config_option("synchronous_commit", opts->synchronous_commit,
                                     PGC_BACKEND, PGC_S_TEST, GUC_ACTION_SET,
                                     false, 0, false);
        }
        else if (IsSet(supported_opts, SUBOPT_REFRESH) &&
                 strcmp(defel->defname, "refresh") == 0)
        {
            if (IsSet(opts->specified_opts, SUBOPT_REFRESH))
                errorConflictingDefElem(defel, pstate);
 
            opts->specified_opts |= SUBOPT_REFRESH;
            opts->refresh = defGetBoolean(defel);
        }
        else if (IsSet(supported_opts, SUBOPT_BINARY) &&
                 strcmp(defel->defname, "binary") == 0)
        {
            if (IsSet(opts->specified_opts, SUBOPT_BINARY))
                errorConflictingDefElem(defel, pstate);
 
            opts->specified_opts |= SUBOPT_BINARY;
            opts->binary = defGetBoolean(defel);
        }
        else if (IsSet(supported_opts, SUBOPT_STREAMING) &&
                 strcmp(defel->defname, "streaming") == 0)
        {
            if (IsSet(opts->specified_opts, SUBOPT_STREAMING))
                errorConflictingDefElem(defel, pstate);
 
            opts->specified_opts |= SUBOPT_STREAMING;
            opts->streaming = defGetStreamingMode(defel);
        }
        else if (IsSet(supported_opts, SUBOPT_TWOPHASE_COMMIT) &&
                 strcmp(defel->defname, "two_phase") == 0)
        {
            if (IsSet(opts->specified_opts, SUBOPT_TWOPHASE_COMMIT))
                errorConflictingDefElem(defel, pstate);
 
            opts->specified_opts |= SUBOPT_TWOPHASE_COMMIT;
            opts->twophase = defGetBoolean(defel);
        }
        else if (IsSet(supported_opts, SUBOPT_DISABLE_ON_ERR) &&
                 strcmp(defel->defname, "disable_on_error") == 0)
        {
            if (IsSet(opts->specified_opts, SUBOPT_DISABLE_ON_ERR))
                errorConflictingDefElem(defel, pstate);
 
            opts->specified_opts |= SUBOPT_DISABLE_ON_ERR;
            opts->disableonerr = defGetBoolean(defel);
        }
        else if (IsSet(supported_opts, SUBOPT_PASSWORD_REQUIRED) &&
                 strcmp(defel->defname, "password_required") == 0)
        {
            if (IsSet(opts->specified_opts, SUBOPT_PASSWORD_REQUIRED))
                errorConflictingDefElem(defel, pstate);
 
            opts->specified_opts |= SUBOPT_PASSWORD_REQUIRED;
            opts->passwordrequired = defGetBoolean(defel);
        }
        else if (IsSet(supported_opts, SUBOPT_RUN_AS_OWNER) &&
                 strcmp(defel->defname, "run_as_owner") == 0)
        {
            if (IsSet(opts->specified_opts, SUBOPT_RUN_AS_OWNER))
                errorConflictingDefElem(defel, pstate);
 
            opts->specified_opts |= SUBOPT_RUN_AS_OWNER;
            opts->runasowner = defGetBoolean(defel);
        }
        else if (IsSet(supported_opts, SUBOPT_FAILOVER) &&
                 strcmp(defel->defname, "failover") == 0)
        {
            if (IsSet(opts->specified_opts, SUBOPT_FAILOVER))
                errorConflictingDefElem(defel, pstate);
 
            opts->specified_opts |= SUBOPT_FAILOVER;
            opts->failover = defGetBoolean(defel);
        }
        else if (IsSet(supported_opts, SUBOPT_RETAIN_DEAD_TUPLES) &&
                 strcmp(defel->defname, "retain_dead_tuples") == 0)
        {
            if (IsSet(opts->specified_opts, SUBOPT_RETAIN_DEAD_TUPLES))
                errorConflictingDefElem(defel, pstate);
 
            opts->specified_opts |= SUBOPT_RETAIN_DEAD_TUPLES;
            opts->retaindeadtuples = defGetBoolean(defel);
        }
        else if (IsSet(supported_opts, SUBOPT_MAX_RETENTION_DURATION) &&
                 strcmp(defel->defname, "max_retention_duration") == 0)
        {
            if (IsSet(opts->specified_opts, SUBOPT_MAX_RETENTION_DURATION))
                errorConflictingDefElem(defel, pstate);
 
            opts->specified_opts |= SUBOPT_MAX_RETENTION_DURATION;
            opts->maxretention = defGetInt32(defel);
        }
        else if (IsSet(supported_opts, SUBOPT_ORIGIN) &&
                 strcmp(defel->defname, "origin") == 0)
        {
            if (IsSet(opts->specified_opts, SUBOPT_ORIGIN))
                errorConflictingDefElem(defel, pstate);
 
            opts->specified_opts |= SUBOPT_ORIGIN;
            pfree(opts->origin);
 
            /*
             * Even though the "origin" parameter allows only "none" and "any"
             * values, it is implemented as a string type so that the
             * parameter can be extended in future versions to support
             * filtering using origin names specified by the user.
             */
            opts->origin = defGetString(defel);
 
            if ((pg_strcasecmp(opts->origin, LOGICALREP_ORIGIN_NONE) != 0) &&
                (pg_strcasecmp(opts->origin, LOGICALREP_ORIGIN_ANY) != 0))
                ereport(ERROR,
                        errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                        errmsg("unrecognized origin value: \"%s\"", opts->origin));
        }
        else if (IsSet(supported_opts, SUBOPT_LSN) &&
                 strcmp(defel->defname, "lsn") == 0)
        {
            char       *lsn_str = defGetString(defel);
            XLogRecPtr  lsn;
 
            if (IsSet(opts->specified_opts, SUBOPT_LSN))
                errorConflictingDefElem(defel, pstate);
 
            /* Setting lsn = NONE is treated as resetting LSN */
            if (strcmp(lsn_str, "none") == 0)
                lsn = InvalidXLogRecPtr;
            else
            {
                /* Parse the argument as LSN */
                lsn = DatumGetLSN(DirectFunctionCall1(pg_lsn_in,
                                                      CStringGetDatum(lsn_str)));
 
                if (!XLogRecPtrIsValid(lsn))
                    ereport(ERROR,
                            (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                             errmsg("invalid WAL location (LSN): %s", lsn_str)));
            }
 
            opts->specified_opts |= SUBOPT_LSN;
            opts->lsn = lsn;
        }
        else if (IsSet(supported_opts, SUBOPT_WAL_RECEIVER_TIMEOUT) &&
                 strcmp(defel->defname, "wal_receiver_timeout") == 0)
        {
            bool        parsed;
            int         val;
 
            if (IsSet(opts->specified_opts, SUBOPT_WAL_RECEIVER_TIMEOUT))
                errorConflictingDefElem(defel, pstate);
 
            opts->specified_opts |= SUBOPT_WAL_RECEIVER_TIMEOUT;
            opts->wal_receiver_timeout = defGetString(defel);
 
            /*
             * Test if the given value is valid for wal_receiver_timeout GUC.
             * Skip this test if the value is -1, since -1 is allowed for the
             * wal_receiver_timeout subscription option, but not for the GUC
             * itself.
             */
            parsed = parse_int(opts->wal_receiver_timeout, &val, 0, NULL);
            if (!parsed || val != -1)
                (void) set_config_option("wal_receiver_timeout", opts->wal_receiver_timeout,
                                         PGC_BACKEND, PGC_S_TEST, GUC_ACTION_SET,
                                         false, 0, false);
        }
        else
            ereport(ERROR,
                    (errcode(ERRCODE_SYNTAX_ERROR),
                     errmsg("unrecognized subscription parameter: \"%s\"", defel->defname)));
    }
 
    /*
     * We've been explicitly asked to not connect, that requires some
     * additional processing.
     */
    if (!opts->connect && IsSet(supported_opts, SUBOPT_CONNECT))
    {
        /* Check for incompatible options from the user. */
        if (opts->enabled &&
            IsSet(opts->specified_opts, SUBOPT_ENABLED))
            ereport(ERROR,
                    (errcode(ERRCODE_SYNTAX_ERROR),
            /*- translator: both %s are strings of the form "option = value" */
                     errmsg("%s and %s are mutually exclusive options",
                            "connect = false", "enabled = true")));
 
        if (opts->create_slot &&
            IsSet(opts->specified_opts, SUBOPT_CREATE_SLOT))
            ereport(ERROR,
                    (errcode(ERRCODE_SYNTAX_ERROR),
                     errmsg("%s and %s are mutually exclusive options",
                            "connect = false", "create_slot = true")));
 
        if (opts->copy_data &&
            IsSet(opts->specified_opts, SUBOPT_COPY_DATA))
            ereport(ERROR,
                    (errcode(ERRCODE_SYNTAX_ERROR),
                     errmsg("%s and %s are mutually exclusive options",
                            "connect = false", "copy_data = true")));
 
        /* Change the defaults of other options. */
        opts->enabled = false;
        opts->create_slot = false;
        opts->copy_data = false;
    }
 
    /*
     * Do additional checking for disallowed combination when slot_name = NONE
     * was used.
     */
    if (!opts->slot_name &&
        IsSet(opts->specified_opts, SUBOPT_SLOT_NAME))
    {
        if (opts->enabled)
        {
            if (IsSet(opts->specified_opts, SUBOPT_ENABLED))
                ereport(ERROR,
                        (errcode(ERRCODE_SYNTAX_ERROR),
                /*- translator: both %s are strings of the form "option = value" */
                         errmsg("%s and %s are mutually exclusive options",
                                "slot_name = NONE", "enabled = true")));
            else
                ereport(ERROR,
                        (errcode(ERRCODE_SYNTAX_ERROR),
                /*- translator: both %s are strings of the form "option = value" */
                         errmsg("subscription with %s must also set %s",
                                "slot_name = NONE", "enabled = false")));
        }
 
        if (opts->create_slot)
        {
            if (IsSet(opts->specified_opts, SUBOPT_CREATE_SLOT))
                ereport(ERROR,
                        (errcode(ERRCODE_SYNTAX_ERROR),
                /*- translator: both %s are strings of the form "option = value" */
                         errmsg("%s and %s are mutually exclusive options",
                                "slot_name = NONE", "create_slot = true")));
            else
                ereport(ERROR,
                        (errcode(ERRCODE_SYNTAX_ERROR),
                /*- translator: both %s are strings of the form "option = value" */
                         errmsg("subscription with %s must also set %s",
                                "slot_name = NONE", "create_slot = false")));
        }
    }
}
 
/*
 * Check that the specified publications are present on the publisher.
 */
static void
check_publications(WalReceiverConn *wrconn, List *publications)
{
    WalRcvExecResult *res;
    StringInfoData cmd;
    TupleTableSlot *slot;
    List       *publicationsCopy = NIL;
    Oid         tableRow[1] = {TEXTOID};
 
    initStringInfo(&cmd);
    appendStringInfoString(&cmd, "SELECT t.pubname FROM\n"
                           " pg_catalog.pg_publication t WHERE\n"
                           " t.pubname IN (");
    GetPublicationsStr(publications, &cmd, true);
    appendStringInfoChar(&cmd, ')');
 
    res = walrcv_exec(wrconn, cmd.data, 1, tableRow);
    pfree(cmd.data);
 
    if (res->status != WALRCV_OK_TUPLES)
        ereport(ERROR,
                errmsg("could not receive list of publications from the publisher: %s",
                       res->err));
 
    publicationsCopy = list_copy(publications);
 
    /* Process publication(s). */
    slot = MakeSingleTupleTableSlot(res->tupledesc, &TTSOpsMinimalTuple);
    while (tuplestore_gettupleslot(res->tuplestore, true, false, slot))
    {
        char       *pubname;
        bool        isnull;
 
        pubname = TextDatumGetCString(slot_getattr(slot, 1, &isnull));
        Assert(!isnull);
 
        /* Delete the publication present in publisher from the list. */
        publicationsCopy = list_delete(publicationsCopy, makeString(pubname));
        ExecClearTuple(slot);
    }
 
    ExecDropSingleTupleTableSlot(slot);
 
    walrcv_clear_result(res);
 
    if (list_length(publicationsCopy))
    {
        /* Prepare the list of non-existent publication(s) for error message. */
        StringInfoData pubnames;
 
        initStringInfo(&pubnames);
 
        GetPublicationsStr(publicationsCopy, &pubnames, false);
        ereport(WARNING,
                errcode(ERRCODE_UNDEFINED_OBJECT),
                errmsg_plural("publication %s does not exist on the publisher",
                              "publications %s do not exist on the publisher",
                              list_length(publicationsCopy),
                              pubnames.data));
    }
}
 
/*
 * Auxiliary function to build a text array out of a list of String nodes.
 */
static Datum
publicationListToArray(List *publist)
{
    ArrayType  *arr;
    Datum      *datums;
    MemoryContext memcxt;
    MemoryContext oldcxt;
 
    /* Create memory context for temporary allocations. */
    memcxt = AllocSetContextCreate(CurrentMemoryContext,
                                   "publicationListToArray to array",
                                   ALLOCSET_DEFAULT_SIZES);
    oldcxt = MemoryContextSwitchTo(memcxt);
 
    datums = palloc_array(Datum, list_length(publist));
 
    check_duplicates_in_publist(publist, datums);
 
    MemoryContextSwitchTo(oldcxt);
 
    arr = construct_array_builtin(datums, list_length(publist), TEXTOID);
 
    MemoryContextDelete(memcxt);
 
    return PointerGetDatum(arr);
}
 
/*
 * Create new subscription.
 */
ObjectAddress
CreateSubscription(ParseState *pstate, CreateSubscriptionStmt *stmt,
                   bool isTopLevel)
{
    Relation    rel;
    ObjectAddress myself;
    Oid         subid;
    bool        nulls[Natts_pg_subscription];
    Datum       values[Natts_pg_subscription];
    Oid         owner = GetUserId();
    HeapTuple   tup;
    Oid         serverid;
    char       *conninfo;
    char        originname[NAMEDATALEN];
    List       *publications;
    uint32      supported_opts;
    SubOpts     opts = {0};
    AclResult   aclresult;
 
    /*
     * Parse and check options.
     *
     * Connection and publication should not be specified here.
     */
    supported_opts = (SUBOPT_CONNECT | SUBOPT_ENABLED | SUBOPT_CREATE_SLOT |
                      SUBOPT_SLOT_NAME | SUBOPT_COPY_DATA |
                      SUBOPT_SYNCHRONOUS_COMMIT | SUBOPT_BINARY |
                      SUBOPT_STREAMING | SUBOPT_TWOPHASE_COMMIT |
                      SUBOPT_DISABLE_ON_ERR | SUBOPT_PASSWORD_REQUIRED |
                      SUBOPT_RUN_AS_OWNER | SUBOPT_FAILOVER |
                      SUBOPT_RETAIN_DEAD_TUPLES |
                      SUBOPT_MAX_RETENTION_DURATION |
                      SUBOPT_WAL_RECEIVER_TIMEOUT | SUBOPT_ORIGIN);
    parse_subscription_options(pstate, stmt->options, supported_opts, &opts);
 
    /*
     * Since creating a replication slot is not transactional, rolling back
     * the transaction leaves the created replication slot.  So we cannot run
     * CREATE SUBSCRIPTION inside a transaction block if creating a
     * replication slot.
     */
    if (opts.create_slot)
        PreventInTransactionBlock(isTopLevel, "CREATE SUBSCRIPTION ... WITH (create_slot = true)");
 
    /*
     * We don't want to allow unprivileged users to be able to trigger
     * attempts to access arbitrary network destinations, so require the user
     * to have been specifically authorized to create subscriptions.
     */
    if (!has_privs_of_role(owner, ROLE_PG_CREATE_SUBSCRIPTION))
        ereport(ERROR,
                (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                 errmsg("permission denied to create subscription"),
                 errdetail("Only roles with privileges of the \"%s\" role may create subscriptions.",
                           "pg_create_subscription")));
 
    /*
     * Since a subscription is a database object, we also check for CREATE
     * permission on the database.
     */
    aclresult = object_aclcheck(DatabaseRelationId, MyDatabaseId,
                                owner, ACL_CREATE);
    if (aclresult != ACLCHECK_OK)
        aclcheck_error(aclresult, OBJECT_DATABASE,
                       get_database_name(MyDatabaseId));
 
    /*
     * Non-superusers are required to set a password for authentication, and
     * that password must be used by the target server, but the superuser can
     * exempt a subscription from this requirement.
     */
    if (!opts.passwordrequired && !superuser_arg(owner))
        ereport(ERROR,
                (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                 errmsg("password_required=false is superuser-only"),
                 errhint("Subscriptions with the password_required option set to false may only be created or modified by the superuser.")));
 
    /*
     * If built with appropriate switch, whine when regression-testing
     * conventions for subscription names are violated.
     */
#ifdef ENFORCE_REGRESSION_TEST_NAME_RESTRICTIONS
    if (strncmp(stmt->subname, "regress_", 8) != 0)
        elog(WARNING, "subscriptions created by regression test cases should have names starting with \"regress_\"");
#endif
 
    rel = table_open(SubscriptionRelationId, RowExclusiveLock);
 
    /* Check if name is used */
    subid = GetSysCacheOid2(SUBSCRIPTIONNAME, Anum_pg_subscription_oid,
                            ObjectIdGetDatum(MyDatabaseId), CStringGetDatum(stmt->subname));
    if (OidIsValid(subid))
    {
        ereport(ERROR,
                (errcode(ERRCODE_DUPLICATE_OBJECT),
                 errmsg("subscription \"%s\" already exists",
                        stmt->subname)));
    }
 
    /*
     * Ensure that system configuration parameters are set appropriately to
     * support retain_dead_tuples and max_retention_duration.
     */
    CheckSubDeadTupleRetention(true, !opts.enabled, WARNING,
                               opts.retaindeadtuples, opts.retaindeadtuples,
                               (opts.maxretention > 0));
 
    if (!IsSet(opts.specified_opts, SUBOPT_SLOT_NAME) &&
        opts.slot_name == NULL)
        opts.slot_name = stmt->subname;
 
    /* The default for synchronous_commit of subscriptions is off. */
    if (opts.synchronous_commit == NULL)
        opts.synchronous_commit = "off";
 
    /*
     * The default for wal_receiver_timeout of subscriptions is -1, which
     * means the value is inherited from the server configuration, command
     * line, or role/database settings.
     */
    if (opts.wal_receiver_timeout == NULL)
        opts.wal_receiver_timeout = "-1";
 
    /* Load the library providing us libpq calls. */
    load_file("libpqwalreceiver", false);
 
    if (stmt->servername)
    {
        ForeignServer *server;
 
        Assert(!stmt->conninfo);
        conninfo = NULL;
 
        server = GetForeignServerByName(stmt->servername, false);
        aclresult = object_aclcheck(ForeignServerRelationId, server->serverid, owner, ACL_USAGE);
        if (aclresult != ACLCHECK_OK)
            aclcheck_error(aclresult, OBJECT_FOREIGN_SERVER, server->servername);
 
        /* make sure a user mapping exists */
        GetUserMapping(owner, server->serverid);
 
        serverid = server->serverid;
        conninfo = ForeignServerConnectionString(owner, server);
    }
    else
    {
        Assert(stmt->conninfo);
 
        serverid = InvalidOid;
        conninfo = stmt->conninfo;
    }
 
    /* Check the connection info string. */
    walrcv_check_conninfo(conninfo, opts.passwordrequired && !superuser());
 
    publications = stmt->publication;
 
    /* Everything ok, form a new tuple. */
    memset(values, 0, sizeof(values));
    memset(nulls, false, sizeof(nulls));
 
    subid = GetNewOidWithIndex(rel, SubscriptionObjectIndexId,
                               Anum_pg_subscription_oid);
    values[Anum_pg_subscription_oid - 1] = ObjectIdGetDatum(subid);
    values[Anum_pg_subscription_subdbid - 1] = ObjectIdGetDatum(MyDatabaseId);
    values[Anum_pg_subscription_subskiplsn - 1] = LSNGetDatum(InvalidXLogRecPtr);
    values[Anum_pg_subscription_subname - 1] =
        DirectFunctionCall1(namein, CStringGetDatum(stmt->subname));
    values[Anum_pg_subscription_subowner - 1] = ObjectIdGetDatum(owner);
    values[Anum_pg_subscription_subenabled - 1] = BoolGetDatum(opts.enabled);
    values[Anum_pg_subscription_subbinary - 1] = BoolGetDatum(opts.binary);
    values[Anum_pg_subscription_substream - 1] = CharGetDatum(opts.streaming);
    values[Anum_pg_subscription_subtwophasestate - 1] =
        CharGetDatum(opts.twophase ?
                     LOGICALREP_TWOPHASE_STATE_PENDING :
                     LOGICALREP_TWOPHASE_STATE_DISABLED);
    values[Anum_pg_subscription_subdisableonerr - 1] = BoolGetDatum(opts.disableonerr);
    values[Anum_pg_subscription_subpasswordrequired - 1] = BoolGetDatum(opts.passwordrequired);
    values[Anum_pg_subscription_subrunasowner - 1] = BoolGetDatum(opts.runasowner);
    values[Anum_pg_subscription_subfailover - 1] = BoolGetDatum(opts.failover);
    values[Anum_pg_subscription_subretaindeadtuples - 1] =
        BoolGetDatum(opts.retaindeadtuples);
    values[Anum_pg_subscription_submaxretention - 1] =
        Int32GetDatum(opts.maxretention);
    values[Anum_pg_subscription_subretentionactive - 1] =
        Int32GetDatum(opts.retaindeadtuples);
    values[Anum_pg_subscription_subserver - 1] = serverid;
    if (!OidIsValid(serverid))
        values[Anum_pg_subscription_subconninfo - 1] =
            CStringGetTextDatum(conninfo);
    else
        nulls[Anum_pg_subscription_subconninfo - 1] = true;
    if (opts.slot_name)
        values[Anum_pg_subscription_subslotname - 1] =
            DirectFunctionCall1(namein, CStringGetDatum(opts.slot_name));
    else
        nulls[Anum_pg_subscription_subslotname - 1] = true;
    values[Anum_pg_subscription_subsynccommit - 1] =
        CStringGetTextDatum(opts.synchronous_commit);
    values[Anum_pg_subscription_subwalrcvtimeout - 1] =
        CStringGetTextDatum(opts.wal_receiver_timeout);
    values[Anum_pg_subscription_subpublications - 1] =
        publicationListToArray(publications);
    values[Anum_pg_subscription_suborigin - 1] =
        CStringGetTextDatum(opts.origin);
 
    tup = heap_form_tuple(RelationGetDescr(rel), values, nulls);
 
    /* Insert tuple into catalog. */
    CatalogTupleInsert(rel, tup);
    heap_freetuple(tup);
 
    recordDependencyOnOwner(SubscriptionRelationId, subid, owner);
 
    ObjectAddressSet(myself, SubscriptionRelationId, subid);
 
    if (stmt->servername)
    {
        ObjectAddress referenced;
 
        Assert(OidIsValid(serverid));
 
        ObjectAddressSet(referenced, ForeignServerRelationId, serverid);
        recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
    }
 
    /*
     * A replication origin is currently created for all subscriptions,
     * including those that only contain sequences or are otherwise empty.
     *
     * XXX: While this is technically unnecessary, optimizing it would require
     * additional logic to skip origin creation during DDL operations and
     * apply workers initialization, and to handle origin creation dynamically
     * when tables are added to the subscription. It is not clear whether
     * preventing creation of origins is worth additional complexity.
     */
    ReplicationOriginNameForLogicalRep(subid, InvalidOid, originname, sizeof(originname));
    replorigin_create(originname);
 
    /*
     * Connect to remote side to execute requested commands and fetch table
     * and sequence info.
     */
    if (opts.connect)
    {
        char       *err;
        WalReceiverConn *wrconn;
        bool        must_use_password;
 
        /* Try to connect to the publisher. */
        must_use_password = !superuser_arg(owner) && opts.passwordrequired;
        wrconn = walrcv_connect(conninfo, true, true, must_use_password,
                                stmt->subname, &err);
        if (!wrconn)
            ereport(ERROR,
                    (errcode(ERRCODE_CONNECTION_FAILURE),
                     errmsg("subscription \"%s\" could not connect to the publisher: %s",
                            stmt->subname, err)));
 
        PG_TRY();
        {
            bool        has_tables = false;
            List       *pubrels;
            char        relation_state;
 
            check_publications(wrconn, publications);
            check_publications_origin_tables(wrconn, publications,
                                             opts.copy_data,
                                             opts.retaindeadtuples, opts.origin,
                                             NULL, 0, stmt->subname);
            check_publications_origin_sequences(wrconn, publications,
                                                opts.copy_data, opts.origin,
                                                NULL, 0, stmt->subname);
 
            if (opts.retaindeadtuples)
                check_pub_dead_tuple_retention(wrconn);
 
            /*
             * Set sync state based on if we were asked to do data copy or
             * not.
             */
            relation_state = opts.copy_data ? SUBREL_STATE_INIT : SUBREL_STATE_READY;
 
            /*
             * Build local relation status info. Relations are for both tables
             * and sequences from the publisher.
             */
            pubrels = fetch_relation_list(wrconn, publications);
 
            foreach_ptr(PublicationRelKind, pubrelinfo, pubrels)
            {
                Oid         relid;
                char        relkind;
                RangeVar   *rv = pubrelinfo->rv;
 
                relid = RangeVarGetRelid(rv, AccessShareLock, false);
                relkind = get_rel_relkind(relid);
 
                /* Check for supported relkind. */
                CheckSubscriptionRelkind(relkind, pubrelinfo->relkind,
                                         rv->schemaname, rv->relname);
                has_tables |= (relkind != RELKIND_SEQUENCE);
                AddSubscriptionRelState(subid, relid, relation_state,
                                        InvalidXLogRecPtr, true);
            }
 
            /*
             * If requested, create permanent slot for the subscription. We
             * won't use the initial snapshot for anything, so no need to
             * export it.
             *
             * XXX: Similar to origins, it is not clear whether preventing the
             * slot creation for empty and sequence-only subscriptions is
             * worth additional complexity.
             */
            if (opts.create_slot)
            {
                bool        twophase_enabled = false;
 
                Assert(opts.slot_name);
 
                /*
                 * Even if two_phase is set, don't create the slot with
                 * two-phase enabled. Will enable it once all the tables are
                 * synced and ready. This avoids race-conditions like prepared
                 * transactions being skipped due to changes not being applied
                 * due to checks in should_apply_changes_for_rel() when
                 * tablesync for the corresponding tables are in progress. See
                 * comments atop worker.c.
                 *
                 * Note that if tables were specified but copy_data is false
                 * then it is safe to enable two_phase up-front because those
                 * tables are already initially in READY state. When the
                 * subscription has no tables, we leave the twophase state as
                 * PENDING, to allow ALTER SUBSCRIPTION ... REFRESH
                 * PUBLICATION to work.
                 */
                if (opts.twophase && !opts.copy_data && has_tables)
                    twophase_enabled = true;
 
                walrcv_create_slot(wrconn, opts.slot_name, false, twophase_enabled,
                                   opts.failover, CRS_NOEXPORT_SNAPSHOT, NULL);
 
                if (twophase_enabled)
                    UpdateTwoPhaseState(subid, LOGICALREP_TWOPHASE_STATE_ENABLED);
 
                ereport(NOTICE,
                        (errmsg("created replication slot \"%s\" on publisher",
                                opts.slot_name)));
            }
        }
        PG_FINALLY();
        {
            walrcv_disconnect(wrconn);
        }
        PG_END_TRY();
    }
    else
        ereport(WARNING,
                (errmsg("subscription was created, but is not connected"),
                 errhint("To initiate replication, you must manually create the replication slot, enable the subscription, and alter the subscription to refresh publications.")));
 
    table_close(rel, RowExclusiveLock);
 
    pgstat_create_subscription(subid);
 
    /*
     * Notify the launcher to start the apply worker if the subscription is
     * enabled, or to create the conflict detection slot if retain_dead_tuples
     * is enabled.
     *
     * Creating the conflict detection slot is essential even when the
     * subscription is not enabled. This ensures that dead tuples are
     * retained, which is necessary for accurately identifying the type of
     * conflict during replication.
     */
    if (opts.enabled || opts.retaindeadtuples)
        ApplyLauncherWakeupAtCommit();
 
    InvokeObjectPostCreateHook(SubscriptionRelationId, subid, 0);
 
    return myself;
}
 
static void
AlterSubscription_refresh(Subscription *sub, bool copy_data,
                          List *validate_publications)
{
    char       *err;
    List       *pubrels = NIL;
    Oid        *pubrel_local_oids;
    List       *subrel_states;
    List       *sub_remove_rels = NIL;
    Oid        *subrel_local_oids;
    Oid        *subseq_local_oids;
    int         subrel_count;
    ListCell   *lc;
    int         off;
    int         tbl_count = 0;
    int         seq_count = 0;
    Relation    rel = NULL;
    typedef struct SubRemoveRels
    {
        Oid         relid;
        char        state;
    } SubRemoveRels;
 
    WalReceiverConn *wrconn;
    bool        must_use_password;
 
    /* Load the library providing us libpq calls. */
    load_file("libpqwalreceiver", false);
 
    /* Try to connect to the publisher. */
    must_use_password = sub->passwordrequired && !sub->ownersuperuser;
    wrconn = walrcv_connect(sub->conninfo, true, true, must_use_password,
                            sub->name, &err);
    if (!wrconn)
        ereport(ERROR,
                (errcode(ERRCODE_CONNECTION_FAILURE),
                 errmsg("subscription \"%s\" could not connect to the publisher: %s",
                        sub->name, err)));
 
    PG_TRY();
    {
        if (validate_publications)
            check_publications(wrconn, validate_publications);
 
        /* Get the relation list from publisher. */
        pubrels = fetch_relation_list(wrconn, sub->publications);
 
        /* Get local relation list. */
        subrel_states = GetSubscriptionRelations(sub->oid, true, true, false);
        subrel_count = list_length(subrel_states);
 
        /*
         * Build qsorted arrays of local table oids and sequence oids for
         * faster lookup. This can potentially contain all tables and
         * sequences in the database so speed of lookup is important.
         *
         * We do not yet know the exact count of tables and sequences, so we
         * allocate separate arrays for table OIDs and sequence OIDs based on
         * the total number of relations (subrel_count).
         */
        subrel_local_oids = palloc(subrel_count * sizeof(Oid));
        subseq_local_oids = palloc(subrel_count * sizeof(Oid));
        foreach(lc, subrel_states)
        {
            SubscriptionRelState *relstate = (SubscriptionRelState *) lfirst(lc);
 
            if (get_rel_relkind(relstate->relid) == RELKIND_SEQUENCE)
                subseq_local_oids[seq_count++] = relstate->relid;
            else
                subrel_local_oids[tbl_count++] = relstate->relid;
        }
 
        qsort(subrel_local_oids, tbl_count, sizeof(Oid), oid_cmp);
        check_publications_origin_tables(wrconn, sub->publications, copy_data,
                                         sub->retaindeadtuples, sub->origin,
                                         subrel_local_oids, tbl_count,
                                         sub->name);
 
        qsort(subseq_local_oids, seq_count, sizeof(Oid), oid_cmp);
        check_publications_origin_sequences(wrconn, sub->publications,
                                            copy_data, sub->origin,
                                            subseq_local_oids, seq_count,
                                            sub->name);
 
        /*
         * Walk over the remote relations and try to match them to locally
         * known relations. If the relation is not known locally create a new
         * state for it.
         *
         * Also builds array of local oids of remote relations for the next
         * step.
         */
        off = 0;
        pubrel_local_oids = palloc(list_length(pubrels) * sizeof(Oid));
 
        foreach_ptr(PublicationRelKind, pubrelinfo, pubrels)
        {
            RangeVar   *rv = pubrelinfo->rv;
            Oid         relid;
            char        relkind;
 
            relid = RangeVarGetRelid(rv, AccessShareLock, false);
            relkind = get_rel_relkind(relid);
 
            /* Check for supported relkind. */
            CheckSubscriptionRelkind(relkind, pubrelinfo->relkind,
                                     rv->schemaname, rv->relname);
 
            pubrel_local_oids[off++] = relid;
 
            if (!bsearch(&relid, subrel_local_oids,
                         tbl_count, sizeof(Oid), oid_cmp) &&
                !bsearch(&relid, subseq_local_oids,
                         seq_count, sizeof(Oid), oid_cmp))
            {
                AddSubscriptionRelState(sub->oid, relid,
                                        copy_data ? SUBREL_STATE_INIT : SUBREL_STATE_READY,
                                        InvalidXLogRecPtr, true);
                ereport(DEBUG1,
                        errmsg_internal("%s \"%s.%s\" added to subscription \"%s\"",
                                        relkind == RELKIND_SEQUENCE ? "sequence" : "table",
                                        rv->schemaname, rv->relname, sub->name));
            }
        }
 
        /*
         * Next remove state for tables we should not care about anymore using
         * the data we collected above
         */
        qsort(pubrel_local_oids, list_length(pubrels), sizeof(Oid), oid_cmp);
 
        for (off = 0; off < tbl_count; off++)
        {
            Oid         relid = subrel_local_oids[off];
 
            if (!bsearch(&relid, pubrel_local_oids,
                         list_length(pubrels), sizeof(Oid), oid_cmp))
            {
                char        state;
                XLogRecPtr  statelsn;
                SubRemoveRels *remove_rel = palloc_object(SubRemoveRels);
 
                /*
                 * Lock pg_subscription_rel with AccessExclusiveLock to
                 * prevent any race conditions with the apply worker
                 * re-launching workers at the same time this code is trying
                 * to remove those tables.
                 *
                 * Even if new worker for this particular rel is restarted it
                 * won't be able to make any progress as we hold exclusive
                 * lock on pg_subscription_rel till the transaction end. It
                 * will simply exit as there is no corresponding rel entry.
                 *
                 * This locking also ensures that the state of rels won't
                 * change till we are done with this refresh operation.
                 */
                if (!rel)
                    rel = table_open(SubscriptionRelRelationId, AccessExclusiveLock);
 
                /* Last known rel state. */
                state = GetSubscriptionRelState(sub->oid, relid, &statelsn);
 
                RemoveSubscriptionRel(sub->oid, relid);
 
                remove_rel->relid = relid;
                remove_rel->state = state;
 
                sub_remove_rels = lappend(sub_remove_rels, remove_rel);
 
                logicalrep_worker_stop(WORKERTYPE_TABLESYNC, sub->oid, relid);
 
                /*
                 * For READY state, we would have already dropped the
                 * tablesync origin.
                 */
                if (state != SUBREL_STATE_READY)
                {
                    char        originname[NAMEDATALEN];
 
                    /*
                     * Drop the tablesync's origin tracking if exists.
                     *
                     * It is possible that the origin is not yet created for
                     * tablesync worker, this can happen for the states before
                     * SUBREL_STATE_DATASYNC. The tablesync worker or apply
                     * worker can also concurrently try to drop the origin and
                     * by this time the origin might be already removed. For
                     * these reasons, passing missing_ok = true.
                     */
                    ReplicationOriginNameForLogicalRep(sub->oid, relid, originname,
                                                       sizeof(originname));
                    replorigin_drop_by_name(originname, true, false);
                }
 
                ereport(DEBUG1,
                        (errmsg_internal("table \"%s.%s\" removed from subscription \"%s\"",
                                         get_namespace_name(get_rel_namespace(relid)),
                                         get_rel_name(relid),
                                         sub->name)));
            }
        }
 
        /*
         * Drop the tablesync slots associated with removed tables. This has
         * to be at the end because otherwise if there is an error while doing
         * the database operations we won't be able to rollback dropped slots.
         */
        foreach_ptr(SubRemoveRels, sub_remove_rel, sub_remove_rels)
        {
            if (sub_remove_rel->state != SUBREL_STATE_READY &&
                sub_remove_rel->state != SUBREL_STATE_SYNCDONE)
            {
                char        syncslotname[NAMEDATALEN] = {0};
 
                /*
                 * For READY/SYNCDONE states we know the tablesync slot has
                 * already been dropped by the tablesync worker.
                 *
                 * For other states, there is no certainty, maybe the slot
                 * does not exist yet. Also, if we fail after removing some of
                 * the slots, next time, it will again try to drop already
                 * dropped slots and fail. For these reasons, we allow
                 * missing_ok = true for the drop.
                 */
                ReplicationSlotNameForTablesync(sub->oid, sub_remove_rel->relid,
                                                syncslotname, sizeof(syncslotname));
                ReplicationSlotDropAtPubNode(wrconn, syncslotname, true);
            }
        }
 
        /*
         * Next remove state for sequences we should not care about anymore
         * using the data we collected above
         */
        for (off = 0; off < seq_count; off++)
        {
            Oid         relid = subseq_local_oids[off];
 
            if (!bsearch(&relid, pubrel_local_oids,
                         list_length(pubrels), sizeof(Oid), oid_cmp))
            {
                /*
                 * This locking ensures that the state of rels won't change
                 * till we are done with this refresh operation.
                 */
                if (!rel)
                    rel = table_open(SubscriptionRelRelationId, AccessExclusiveLock);
 
                RemoveSubscriptionRel(sub->oid, relid);
 
                ereport(DEBUG1,
                        errmsg_internal("sequence \"%s.%s\" removed from subscription \"%s\"",
                                        get_namespace_name(get_rel_namespace(relid)),
                                        get_rel_name(relid),
                                        sub->name));
            }
        }
    }
    PG_FINALLY();
    {
        walrcv_disconnect(wrconn);
    }
    PG_END_TRY();
 
    if (rel)
        table_close(rel, NoLock);
}
 
/*
 * Marks all sequences with INIT state.
 */
static void
AlterSubscription_refresh_seq(Subscription *sub)
{
    char       *err = NULL;
    WalReceiverConn *wrconn;
    bool        must_use_password;
 
    /* Load the library providing us libpq calls. */
    load_file("libpqwalreceiver", false);
 
    /* Try to connect to the publisher. */
    must_use_password = sub->passwordrequired && !sub->ownersuperuser;
    wrconn = walrcv_connect(sub->conninfo, true, true, must_use_password,
                            sub->name, &err);
    if (!wrconn)
        ereport(ERROR,
                errcode(ERRCODE_CONNECTION_FAILURE),
                errmsg("subscription \"%s\" could not connect to the publisher: %s",
                       sub->name, err));
 
    PG_TRY();
    {
        List       *subrel_states;
 
        check_publications_origin_sequences(wrconn, sub->publications, true,
                                            sub->origin, NULL, 0, sub->name);
 
        /* Get local sequence list. */
        subrel_states = GetSubscriptionRelations(sub->oid, false, true, false);
        foreach_ptr(SubscriptionRelState, subrel, subrel_states)
        {
            Oid         relid = subrel->relid;
 
            UpdateSubscriptionRelState(sub->oid, relid, SUBREL_STATE_INIT,
                                       InvalidXLogRecPtr, false);
            ereport(DEBUG1,
                    errmsg_internal("sequence \"%s.%s\" of subscription \"%s\" set to INIT state",
                                    get_namespace_name(get_rel_namespace(relid)),
                                    get_rel_name(relid),
                                    sub->name));
        }
    }
    PG_FINALLY();
    {
        walrcv_disconnect(wrconn);
    }
    PG_END_TRY();
}
 
/*
 * Common checks for altering failover, two_phase, and retain_dead_tuples
 * options.
 */
static void
CheckAlterSubOption(Subscription *sub, const char *option,
                    bool slot_needs_update, bool isTopLevel)
{
    Assert(strcmp(option, "failover") == 0 ||
           strcmp(option, "two_phase") == 0 ||
           strcmp(option, "retain_dead_tuples") == 0);
 
    /*
     * Altering the retain_dead_tuples option does not update the slot on the
     * publisher.
     */
    Assert(!slot_needs_update || strcmp(option, "retain_dead_tuples") != 0);
 
    /*
     * Do not allow changing the option if the subscription is enabled. This
     * is because both failover and two_phase options of the slot on the
     * publisher cannot be modified if the slot is currently acquired by the
     * existing walsender.
     *
     * Note that two_phase is enabled (aka changed from 'false' to 'true') on
     * the publisher by the existing walsender, so we could have allowed that
     * even when the subscription is enabled. But we kept this restriction for
     * the sake of consistency and simplicity.
     *
     * Additionally, do not allow changing the retain_dead_tuples option when
     * the subscription is enabled to prevent race conditions arising from the
     * new option value being acknowledged asynchronously by the launcher and
     * apply workers.
     *
     * Without the restriction, a race condition may arise when a user
     * disables and immediately re-enables the retain_dead_tuples option. In
     * this case, the launcher might drop the slot upon noticing the disabled
     * action, while the apply worker may keep maintaining
     * oldest_nonremovable_xid without noticing the option change. During this
     * period, a transaction ID wraparound could falsely make this ID appear
     * as if it originates from the future w.r.t the transaction ID stored in
     * the slot maintained by launcher.
     *
     * Similarly, if the user enables retain_dead_tuples concurrently with the
     * launcher starting the worker, the apply worker may start calculating
     * oldest_nonremovable_xid before the launcher notices the enable action.
     * Consequently, the launcher may update slot.xmin to a newer value than
     * that maintained by the worker. In subsequent cycles, upon integrating
     * the worker's oldest_nonremovable_xid, the launcher might detect a
     * retreat in the calculated xmin, necessitating additional handling.
     *
     * XXX To address the above race conditions, we can define
     * oldest_nonremovable_xid as FullTransactionId and adds the check to
     * disallow retreating the conflict slot's xmin. For now, we kept the
     * implementation simple by disallowing change to the retain_dead_tuples,
     * but in the future we can change this after some more analysis.
     *
     * Note that we could restrict only the enabling of retain_dead_tuples to
     * avoid the race conditions described above, but we maintain the
     * restriction for both enable and disable operations for the sake of
     * consistency.
     */
    if (sub->enabled)
        ereport(ERROR,
                (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                 errmsg("cannot set option \"%s\" for enabled subscription",
                        option)));
 
    if (slot_needs_update)
    {
        StringInfoData cmd;
 
        /*
         * A valid slot must be associated with the subscription for us to
         * modify any of the slot's properties.
         */
        if (!sub->slotname)
            ereport(ERROR,
                    (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                     errmsg("cannot set option \"%s\" for a subscription that does not have a slot name",
                            option)));
 
        /* The changed option of the slot can't be rolled back. */
        initStringInfo(&cmd);
        appendStringInfo(&cmd, "ALTER SUBSCRIPTION ... SET (%s)", option);
 
        PreventInTransactionBlock(isTopLevel, cmd.data);
        pfree(cmd.data);
    }
}
 
/*
 * Alter the existing subscription.
 */
ObjectAddress
AlterSubscription(ParseState *pstate, AlterSubscriptionStmt *stmt,
                  bool isTopLevel)
{
    Relation    rel;
    ObjectAddress myself;
    bool        nulls[Natts_pg_subscription];
    bool        replaces[Natts_pg_subscription];
    Datum       values[Natts_pg_subscription];
    HeapTuple   tup;
    Oid         subid;
    bool        update_tuple = false;
    bool        update_failover = false;
    bool        update_two_phase = false;
    bool        check_pub_rdt = false;
    bool        retain_dead_tuples;
    int         max_retention;
    bool        retention_active;
    char       *origin;
    Subscription *sub;
    Form_pg_subscription form;
    uint32      supported_opts;
    SubOpts     opts = {0};
 
    rel = table_open(SubscriptionRelationId, RowExclusiveLock);
 
    /* Fetch the existing tuple. */
    tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME, ObjectIdGetDatum(MyDatabaseId),
                              CStringGetDatum(stmt->subname));
 
    if (!HeapTupleIsValid(tup))
        ereport(ERROR,
                (errcode(ERRCODE_UNDEFINED_OBJECT),
                 errmsg("subscription \"%s\" does not exist",
                        stmt->subname)));
 
    form = (Form_pg_subscription) GETSTRUCT(tup);
    subid = form->oid;
 
    /* must be owner */
    if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
        aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
                       stmt->subname);
 
    /*
     * Skip ACL checks on the subscription's foreign server, if any. If
     * changing the server (or replacing it with a raw connection), then the
     * old one will be removed anyway. If changing something unrelated,
     * there's no need to do an additional ACL check here; that will be done
     * by the subscription worker anyway.
     */
    sub = GetSubscription(subid, false, false);
 
    retain_dead_tuples = sub->retaindeadtuples;
    origin = sub->origin;
    max_retention = sub->maxretention;
    retention_active = sub->retentionactive;
 
    /*
     * Don't allow non-superuser modification of a subscription with
     * password_required=false.
     */
    if (!sub->passwordrequired && !superuser())
        ereport(ERROR,
                (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                 errmsg("password_required=false is superuser-only"),
                 errhint("Subscriptions with the password_required option set to false may only be created or modified by the superuser.")));
 
    /* Lock the subscription so nobody else can do anything with it. */
    LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
 
    /* Form a new tuple. */
    memset(values, 0, sizeof(values));
    memset(nulls, false, sizeof(nulls));
    memset(replaces, false, sizeof(replaces));
 
    ObjectAddressSet(myself, SubscriptionRelationId, subid);
 
    switch (stmt->kind)
    {
        case ALTER_SUBSCRIPTION_OPTIONS:
            {
                supported_opts = (SUBOPT_SLOT_NAME |
                                  SUBOPT_SYNCHRONOUS_COMMIT | SUBOPT_BINARY |
                                  SUBOPT_STREAMING | SUBOPT_TWOPHASE_COMMIT |
                                  SUBOPT_DISABLE_ON_ERR |
                                  SUBOPT_PASSWORD_REQUIRED |
                                  SUBOPT_RUN_AS_OWNER | SUBOPT_FAILOVER |
                                  SUBOPT_RETAIN_DEAD_TUPLES |
                                  SUBOPT_MAX_RETENTION_DURATION |
                                  SUBOPT_WAL_RECEIVER_TIMEOUT |
                                  SUBOPT_ORIGIN);
 
                parse_subscription_options(pstate, stmt->options,
                                           supported_opts, &opts);
 
                if (IsSet(opts.specified_opts, SUBOPT_SLOT_NAME))
                {
                    /*
                     * The subscription must be disabled to allow slot_name as
                     * 'none', otherwise, the apply worker will repeatedly try
                     * to stream the data using that slot_name which neither
                     * exists on the publisher nor the user will be allowed to
                     * create it.
                     */
                    if (sub->enabled && !opts.slot_name)
                        ereport(ERROR,
                                (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                                 errmsg("cannot set %s for enabled subscription",
                                        "slot_name = NONE")));
 
                    if (opts.slot_name)
                        values[Anum_pg_subscription_subslotname - 1] =
                            DirectFunctionCall1(namein, CStringGetDatum(opts.slot_name));
                    else
                        nulls[Anum_pg_subscription_subslotname - 1] = true;
                    replaces[Anum_pg_subscription_subslotname - 1] = true;
                }
 
                if (opts.synchronous_commit)
                {
                    values[Anum_pg_subscription_subsynccommit - 1] =
                        CStringGetTextDatum(opts.synchronous_commit);
                    replaces[Anum_pg_subscription_subsynccommit - 1] = true;
                }
 
                if (IsSet(opts.specified_opts, SUBOPT_BINARY))
                {
                    values[Anum_pg_subscription_subbinary - 1] =
                        BoolGetDatum(opts.binary);
                    replaces[Anum_pg_subscription_subbinary - 1] = true;
                }
 
                if (IsSet(opts.specified_opts, SUBOPT_STREAMING))
                {
                    values[Anum_pg_subscription_substream - 1] =
                        CharGetDatum(opts.streaming);
                    replaces[Anum_pg_subscription_substream - 1] = true;
                }
 
                if (IsSet(opts.specified_opts, SUBOPT_DISABLE_ON_ERR))
                {
                    values[Anum_pg_subscription_subdisableonerr - 1]
                        = BoolGetDatum(opts.disableonerr);
                    replaces[Anum_pg_subscription_subdisableonerr - 1]
                        = true;
                }
 
                if (IsSet(opts.specified_opts, SUBOPT_PASSWORD_REQUIRED))
                {
                    /* Non-superuser may not disable password_required. */
                    if (!opts.passwordrequired && !superuser())
                        ereport(ERROR,
                                (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                                 errmsg("password_required=false is superuser-only"),
                                 errhint("Subscriptions with the password_required option set to false may only be created or modified by the superuser.")));
 
                    values[Anum_pg_subscription_subpasswordrequired - 1]
                        = BoolGetDatum(opts.passwordrequired);
                    replaces[Anum_pg_subscription_subpasswordrequired - 1]
                        = true;
                }
 
                if (IsSet(opts.specified_opts, SUBOPT_RUN_AS_OWNER))
                {
                    values[Anum_pg_subscription_subrunasowner - 1] =
                        BoolGetDatum(opts.runasowner);
                    replaces[Anum_pg_subscription_subrunasowner - 1] = true;
                }
 
                if (IsSet(opts.specified_opts, SUBOPT_TWOPHASE_COMMIT))
                {
                    /*
                     * We need to update both the slot and the subscription
                     * for the two_phase option. We can enable the two_phase
                     * option for a slot only once the initial data
                     * synchronization is done. This is to avoid missing some
                     * data as explained in comments atop worker.c.
                     */
                    update_two_phase = !opts.twophase;
 
                    CheckAlterSubOption(sub, "two_phase", update_two_phase,
                                        isTopLevel);
 
                    /*
                     * Modifying the two_phase slot option requires a slot
                     * lookup by slot name, so changing the slot name at the
                     * same time is not allowed.
                     */
                    if (update_two_phase &&
                        IsSet(opts.specified_opts, SUBOPT_SLOT_NAME))
                        ereport(ERROR,
                                (errcode(ERRCODE_SYNTAX_ERROR),
                                 errmsg("\"slot_name\" and \"two_phase\" cannot be altered at the same time")));
 
                    /*
                     * Note that workers may still survive even if the
                     * subscription has been disabled.
                     *
                     * Ensure workers have already been exited to avoid
                     * getting prepared transactions while we are disabling
                     * the two_phase option. Otherwise, the changes of an
                     * already prepared transaction can be replicated again
                     * along with its corresponding commit, leading to
                     * duplicate data or errors.
                     */
                    if (logicalrep_workers_find(subid, true, true))
                        ereport(ERROR,
                                (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                                 errmsg("cannot alter \"two_phase\" when logical replication worker is still running"),
                                 errhint("Try again after some time.")));
 
                    /*
                     * two_phase cannot be disabled if there are any
                     * uncommitted prepared transactions present otherwise it
                     * can lead to duplicate data or errors as explained in
                     * the comment above.
                     */
                    if (update_two_phase &&
                        sub->twophasestate == LOGICALREP_TWOPHASE_STATE_ENABLED &&
                        LookupGXactBySubid(subid))
                        ereport(ERROR,
                                (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                                 errmsg("cannot disable \"two_phase\" when prepared transactions exist"),
                                 errhint("Resolve these transactions and try again.")));
 
                    /* Change system catalog accordingly */
                    values[Anum_pg_subscription_subtwophasestate - 1] =
                        CharGetDatum(opts.twophase ?
                                     LOGICALREP_TWOPHASE_STATE_PENDING :
                                     LOGICALREP_TWOPHASE_STATE_DISABLED);
                    replaces[Anum_pg_subscription_subtwophasestate - 1] = true;
                }
 
                if (IsSet(opts.specified_opts, SUBOPT_FAILOVER))
                {
                    /*
                     * Similar to the two_phase case above, we need to update
                     * the failover option for both the slot and the
                     * subscription.
                     */
                    update_failover = true;
 
                    CheckAlterSubOption(sub, "failover", update_failover,
                                        isTopLevel);
 
                    values[Anum_pg_subscription_subfailover - 1] =
                        BoolGetDatum(opts.failover);
                    replaces[Anum_pg_subscription_subfailover - 1] = true;
                }
 
                if (IsSet(opts.specified_opts, SUBOPT_RETAIN_DEAD_TUPLES))
                {
                    values[Anum_pg_subscription_subretaindeadtuples - 1] =
                        BoolGetDatum(opts.retaindeadtuples);
                    replaces[Anum_pg_subscription_subretaindeadtuples - 1] = true;
 
                    /*
                     * Update the retention status only if there's a change in
                     * the retain_dead_tuples option value.
                     *
                     * Automatically marking retention as active when
                     * retain_dead_tuples is enabled may not always be ideal,
                     * especially if retention was previously stopped and the
                     * user toggles retain_dead_tuples without adjusting the
                     * publisher workload. However, this behavior provides a
                     * convenient way for users to manually refresh the
                     * retention status. Since retention will be stopped again
                     * unless the publisher workload is reduced, this approach
                     * is acceptable for now.
                     */
                    if (opts.retaindeadtuples != sub->retaindeadtuples)
                    {
                        values[Anum_pg_subscription_subretentionactive - 1] =
                            BoolGetDatum(opts.retaindeadtuples);
                        replaces[Anum_pg_subscription_subretentionactive - 1] = true;
 
                        retention_active = opts.retaindeadtuples;
                    }
 
                    CheckAlterSubOption(sub, "retain_dead_tuples", false, isTopLevel);
 
                    /*
                     * Workers may continue running even after the
                     * subscription has been disabled.
                     *
                     * To prevent race conditions (as described in
                     * CheckAlterSubOption()), ensure that all worker
                     * processes have already exited before proceeding.
                     */
                    if (logicalrep_workers_find(subid, true, true))
                        ereport(ERROR,
                                (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                                 errmsg("cannot alter retain_dead_tuples when logical replication worker is still running"),
                                 errhint("Try again after some time.")));
 
                    /*
                     * Notify the launcher to manage the replication slot for
                     * conflict detection. This ensures that replication slot
                     * is efficiently handled (created, updated, or dropped)
                     * in response to any configuration changes.
                     */
                    ApplyLauncherWakeupAtCommit();
 
                    check_pub_rdt = opts.retaindeadtuples;
                    retain_dead_tuples = opts.retaindeadtuples;
                }
 
                if (IsSet(opts.specified_opts, SUBOPT_MAX_RETENTION_DURATION))
                {
                    values[Anum_pg_subscription_submaxretention - 1] =
                        Int32GetDatum(opts.maxretention);
                    replaces[Anum_pg_subscription_submaxretention - 1] = true;
 
                    max_retention = opts.maxretention;
                }
 
                /*
                 * Ensure that system configuration parameters are set
                 * appropriately to support retain_dead_tuples and
                 * max_retention_duration.
                 */
                if (IsSet(opts.specified_opts, SUBOPT_RETAIN_DEAD_TUPLES) ||
                    IsSet(opts.specified_opts, SUBOPT_MAX_RETENTION_DURATION))
                    CheckSubDeadTupleRetention(true, !sub->enabled, NOTICE,
                                               retain_dead_tuples,
                                               retention_active,
                                               (max_retention > 0));
 
                if (IsSet(opts.specified_opts, SUBOPT_ORIGIN))
                {
                    values[Anum_pg_subscription_suborigin - 1] =
                        CStringGetTextDatum(opts.origin);
                    replaces[Anum_pg_subscription_suborigin - 1] = true;
 
                    /*
                     * Check if changes from different origins may be received
                     * from the publisher when the origin is changed to ANY
                     * and retain_dead_tuples is enabled.
                     */
                    check_pub_rdt = retain_dead_tuples &&
                        pg_strcasecmp(opts.origin, LOGICALREP_ORIGIN_ANY) == 0;
 
                    origin = opts.origin;
                }
 
                if (IsSet(opts.specified_opts, SUBOPT_WAL_RECEIVER_TIMEOUT))
                {
                    values[Anum_pg_subscription_subwalrcvtimeout - 1] =
                        CStringGetTextDatum(opts.wal_receiver_timeout);
                    replaces[Anum_pg_subscription_subwalrcvtimeout - 1] = true;
                }
 
                update_tuple = true;
                break;
            }
 
        case ALTER_SUBSCRIPTION_ENABLED:
            {
                parse_subscription_options(pstate, stmt->options,
                                           SUBOPT_ENABLED, &opts);
                Assert(IsSet(opts.specified_opts, SUBOPT_ENABLED));
 
                if (!sub->slotname && opts.enabled)
                    ereport(ERROR,
                            (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                             errmsg("cannot enable subscription that does not have a slot name")));
 
                /*
                 * Check track_commit_timestamp only when enabling the
                 * subscription in case it was disabled after creation. See
                 * comments atop CheckSubDeadTupleRetention() for details.
                 */
                CheckSubDeadTupleRetention(opts.enabled, !opts.enabled,
                                           WARNING, sub->retaindeadtuples,
                                           sub->retentionactive, false);
 
                values[Anum_pg_subscription_subenabled - 1] =
                    BoolGetDatum(opts.enabled);
                replaces[Anum_pg_subscription_subenabled - 1] = true;
 
                if (opts.enabled)
                    ApplyLauncherWakeupAtCommit();
 
                update_tuple = true;
 
                /*
                 * The subscription might be initially created with
                 * connect=false and retain_dead_tuples=true, meaning the
                 * remote server's status may not be checked. Ensure this
                 * check is conducted now.
                 */
                check_pub_rdt = sub->retaindeadtuples && opts.enabled;
                break;
            }
 
        case ALTER_SUBSCRIPTION_SERVER:
            {
                ForeignServer *new_server;
                ObjectAddress referenced;
                AclResult   aclresult;
                char       *conninfo;
 
                /*
                 * Remove what was there before, either another foreign server
                 * or a connection string.
                 */
                if (form->subserver)
                {
                    deleteDependencyRecordsForSpecific(SubscriptionRelationId, form->oid,
                                                       DEPENDENCY_NORMAL,
                                                       ForeignServerRelationId, form->subserver);
                }
                else
                {
                    nulls[Anum_pg_subscription_subconninfo - 1] = true;
                    replaces[Anum_pg_subscription_subconninfo - 1] = true;
                }
 
                /*
                 * Check that the subscription owner has USAGE privileges on
                 * the server.
                 */
                new_server = GetForeignServerByName(stmt->servername, false);
                aclresult = object_aclcheck(ForeignServerRelationId,
                                            new_server->serverid,
                                            form->subowner, ACL_USAGE);
                if (aclresult != ACLCHECK_OK)
                    ereport(ERROR,
                            errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                            errmsg("subscription owner \"%s\" does not have permission on foreign server \"%s\"",
                                   GetUserNameFromId(form->subowner, false),
                                   new_server->servername));
 
                /* make sure a user mapping exists */
                GetUserMapping(form->subowner, new_server->serverid);
 
                conninfo = ForeignServerConnectionString(form->subowner,
                                                         new_server);
 
                /* Load the library providing us libpq calls. */
                load_file("libpqwalreceiver", false);
                /* Check the connection info string. */
                walrcv_check_conninfo(conninfo,
                                      sub->passwordrequired && !sub->ownersuperuser);
 
                values[Anum_pg_subscription_subserver - 1] = new_server->serverid;
                replaces[Anum_pg_subscription_subserver - 1] = true;
 
                ObjectAddressSet(referenced, ForeignServerRelationId, new_server->serverid);
                recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
 
                update_tuple = true;
            }
            break;
 
        case ALTER_SUBSCRIPTION_CONNECTION:
            /* remove reference to foreign server and dependencies, if present */
            if (form->subserver)
            {
                deleteDependencyRecordsForSpecific(SubscriptionRelationId, form->oid,
                                                   DEPENDENCY_NORMAL,
                                                   ForeignServerRelationId, form->subserver);
 
                values[Anum_pg_subscription_subserver - 1] = InvalidOid;
                replaces[Anum_pg_subscription_subserver - 1] = true;
            }
 
            /* Load the library providing us libpq calls. */
            load_file("libpqwalreceiver", false);
            /* Check the connection info string. */
            walrcv_check_conninfo(stmt->conninfo,
                                  sub->passwordrequired && !sub->ownersuperuser);
 
            values[Anum_pg_subscription_subconninfo - 1] =
                CStringGetTextDatum(stmt->conninfo);
            replaces[Anum_pg_subscription_subconninfo - 1] = true;
            update_tuple = true;
 
            /*
             * Since the remote server configuration might have changed,
             * perform a check to ensure it permits enabling
             * retain_dead_tuples.
             */
            check_pub_rdt = sub->retaindeadtuples;
            break;
 
        case ALTER_SUBSCRIPTION_SET_PUBLICATION:
            {
                supported_opts = SUBOPT_COPY_DATA | SUBOPT_REFRESH;
                parse_subscription_options(pstate, stmt->options,
                                           supported_opts, &opts);
 
                values[Anum_pg_subscription_subpublications - 1] =
                    publicationListToArray(stmt->publication);
                replaces[Anum_pg_subscription_subpublications - 1] = true;
 
                update_tuple = true;
 
                /* Refresh if user asked us to. */
                if (opts.refresh)
                {
                    if (!sub->enabled)
                        ereport(ERROR,
                                (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                                 errmsg("ALTER SUBSCRIPTION with refresh is not allowed for disabled subscriptions"),
                                 errhint("Use ALTER SUBSCRIPTION ... SET PUBLICATION ... WITH (refresh = false).")));
 
                    /*
                     * See ALTER_SUBSCRIPTION_REFRESH_PUBLICATION for details
                     * why this is not allowed.
                     */
                    if (sub->twophasestate == LOGICALREP_TWOPHASE_STATE_ENABLED && opts.copy_data)
                        ereport(ERROR,
                                (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                                 errmsg("ALTER SUBSCRIPTION with refresh and copy_data is not allowed when two_phase is enabled"),
                                 errhint("Use ALTER SUBSCRIPTION ... SET PUBLICATION with refresh = false, or with copy_data = false, or use DROP/CREATE SUBSCRIPTION.")));
 
                    PreventInTransactionBlock(isTopLevel, "ALTER SUBSCRIPTION with refresh");
 
                    /* Make sure refresh sees the new list of publications. */
                    sub->publications = stmt->publication;
 
                    AlterSubscription_refresh(sub, opts.copy_data,
                                              stmt->publication);
                }
 
                break;
            }
 
        case ALTER_SUBSCRIPTION_ADD_PUBLICATION:
        case ALTER_SUBSCRIPTION_DROP_PUBLICATION:
            {
                List       *publist;
                bool        isadd = stmt->kind == ALTER_SUBSCRIPTION_ADD_PUBLICATION;
 
                supported_opts = SUBOPT_REFRESH | SUBOPT_COPY_DATA;
                parse_subscription_options(pstate, stmt->options,
                                           supported_opts, &opts);
 
                publist = merge_publications(sub->publications, stmt->publication, isadd, stmt->subname);
                values[Anum_pg_subscription_subpublications - 1] =
                    publicationListToArray(publist);
                replaces[Anum_pg_subscription_subpublications - 1] = true;
 
                update_tuple = true;
 
                /* Refresh if user asked us to. */
                if (opts.refresh)
                {
                    /* We only need to validate user specified publications. */
                    List       *validate_publications = (isadd) ? stmt->publication : NULL;
 
                    if (!sub->enabled)
                        ereport(ERROR,
                                (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                                 errmsg("ALTER SUBSCRIPTION with refresh is not allowed for disabled subscriptions"),
                        /* translator: %s is an SQL ALTER command */
                                 errhint("Use %s instead.",
                                         isadd ?
                                         "ALTER SUBSCRIPTION ... ADD PUBLICATION ... WITH (refresh = false)" :
                                         "ALTER SUBSCRIPTION ... DROP PUBLICATION ... WITH (refresh = false)")));
 
                    /*
                     * See ALTER_SUBSCRIPTION_REFRESH_PUBLICATION for details
                     * why this is not allowed.
                     */
                    if (sub->twophasestate == LOGICALREP_TWOPHASE_STATE_ENABLED && opts.copy_data)
                        ereport(ERROR,
                                (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                                 errmsg("ALTER SUBSCRIPTION with refresh and copy_data is not allowed when two_phase is enabled"),
                        /* translator: %s is an SQL ALTER command */
                                 errhint("Use %s with refresh = false, or with copy_data = false, or use DROP/CREATE SUBSCRIPTION.",
                                         isadd ?
                                         "ALTER SUBSCRIPTION ... ADD PUBLICATION" :
                                         "ALTER SUBSCRIPTION ... DROP PUBLICATION")));
 
                    PreventInTransactionBlock(isTopLevel, "ALTER SUBSCRIPTION with refresh");
 
                    /* Refresh the new list of publications. */
                    sub->publications = publist;
 
                    AlterSubscription_refresh(sub, opts.copy_data,
                                              validate_publications);
                }
 
                break;
            }
 
        case ALTER_SUBSCRIPTION_REFRESH_PUBLICATION:
            {
                if (!sub->enabled)
                    ereport(ERROR,
                            (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                             errmsg("%s is not allowed for disabled subscriptions",
                                    "ALTER SUBSCRIPTION ... REFRESH PUBLICATION")));
 
                parse_subscription_options(pstate, stmt->options,
                                           SUBOPT_COPY_DATA, &opts);
 
                /*
                 * The subscription option "two_phase" requires that
                 * replication has passed the initial table synchronization
                 * phase before the two_phase becomes properly enabled.
                 *
                 * But, having reached this two-phase commit "enabled" state
                 * we must not allow any subsequent table initialization to
                 * occur. So the ALTER SUBSCRIPTION ... REFRESH PUBLICATION is
                 * disallowed when the user had requested two_phase = on mode.
                 *
                 * The exception to this restriction is when copy_data =
                 * false, because when copy_data is false the tablesync will
                 * start already in READY state and will exit directly without
                 * doing anything.
                 *
                 * For more details see comments atop worker.c.
                 */
                if (sub->twophasestate == LOGICALREP_TWOPHASE_STATE_ENABLED && opts.copy_data)
                    ereport(ERROR,
                            (errcode(ERRCODE_SYNTAX_ERROR),
                             errmsg("ALTER SUBSCRIPTION ... REFRESH PUBLICATION with copy_data is not allowed when two_phase is enabled"),
                             errhint("Use ALTER SUBSCRIPTION ... REFRESH PUBLICATION with copy_data = false, or use DROP/CREATE SUBSCRIPTION.")));
 
                PreventInTransactionBlock(isTopLevel, "ALTER SUBSCRIPTION ... REFRESH PUBLICATION");
 
                AlterSubscription_refresh(sub, opts.copy_data, NULL);
 
                break;
            }
 
        case ALTER_SUBSCRIPTION_REFRESH_SEQUENCES:
            {
                if (!sub->enabled)
                    ereport(ERROR,
                            errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                            errmsg("%s is not allowed for disabled subscriptions",
                                   "ALTER SUBSCRIPTION ... REFRESH SEQUENCES"));
 
                AlterSubscription_refresh_seq(sub);
 
                break;
            }
 
        case ALTER_SUBSCRIPTION_SKIP:
            {
                parse_subscription_options(pstate, stmt->options, SUBOPT_LSN, &opts);
 
                /* ALTER SUBSCRIPTION ... SKIP supports only LSN option */
                Assert(IsSet(opts.specified_opts, SUBOPT_LSN));
 
                /*
                 * If the user sets subskiplsn, we do a sanity check to make
                 * sure that the specified LSN is a probable value.
                 */
                if (XLogRecPtrIsValid(opts.lsn))
                {
                    ReplOriginId originid;
                    char        originname[NAMEDATALEN];
                    XLogRecPtr  remote_lsn;
 
                    ReplicationOriginNameForLogicalRep(subid, InvalidOid,
                                                       originname, sizeof(originname));
                    originid = replorigin_by_name(originname, false);
                    remote_lsn = replorigin_get_progress(originid, false);
 
                    /* Check the given LSN is at least a future LSN */
                    if (XLogRecPtrIsValid(remote_lsn) && opts.lsn < remote_lsn)
                        ereport(ERROR,
                                (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                                 errmsg("skip WAL location (LSN %X/%08X) must be greater than origin LSN %X/%08X",
                                        LSN_FORMAT_ARGS(opts.lsn),
                                        LSN_FORMAT_ARGS(remote_lsn))));
                }
 
                values[Anum_pg_subscription_subskiplsn - 1] = LSNGetDatum(opts.lsn);
                replaces[Anum_pg_subscription_subskiplsn - 1] = true;
 
                update_tuple = true;
                break;
            }
 
        default:
            elog(ERROR, "unrecognized ALTER SUBSCRIPTION kind %d",
                 stmt->kind);
    }
 
    /* Update the catalog if needed. */
    if (update_tuple)
    {
        tup = heap_modify_tuple(tup, RelationGetDescr(rel), values, nulls,
                                replaces);
 
        CatalogTupleUpdate(rel, &tup->t_self, tup);
 
        heap_freetuple(tup);
    }
 
    /*
     * Try to acquire the connection necessary either for modifying the slot
     * or for checking if the remote server permits enabling
     * retain_dead_tuples.
     *
     * This has to be at the end because otherwise if there is an error while
     * doing the database operations we won't be able to rollback altered
     * slot.
     */
    if (update_failover || update_two_phase || check_pub_rdt)
    {
        bool        must_use_password;
        char       *err;
        WalReceiverConn *wrconn;
 
        /* Load the library providing us libpq calls. */
        load_file("libpqwalreceiver", false);
 
        /*
         * Try to connect to the publisher, using the new connection string if
         * available.
         */
        must_use_password = sub->passwordrequired && !sub->ownersuperuser;
        wrconn = walrcv_connect(stmt->conninfo ? stmt->conninfo : sub->conninfo,
                                true, true, must_use_password, sub->name,
                                &err);
        if (!wrconn)
            ereport(ERROR,
                    (errcode(ERRCODE_CONNECTION_FAILURE),
                     errmsg("subscription \"%s\" could not connect to the publisher: %s",
                            sub->name, err)));
 
        PG_TRY();
        {
            if (retain_dead_tuples)
                check_pub_dead_tuple_retention(wrconn);
 
            check_publications_origin_tables(wrconn, sub->publications, false,
                                             retain_dead_tuples, origin, NULL, 0,
                                             sub->name);
 
            if (update_failover || update_two_phase)
                walrcv_alter_slot(wrconn, sub->slotname,
                                  update_failover ? &opts.failover : NULL,
                                  update_two_phase ? &opts.twophase : NULL);
        }
        PG_FINALLY();
        {
            walrcv_disconnect(wrconn);
        }
        PG_END_TRY();
    }
 
    table_close(rel, RowExclusiveLock);
 
    InvokeObjectPostAlterHook(SubscriptionRelationId, subid, 0);
 
    /* Wake up related replication workers to handle this change quickly. */
    LogicalRepWorkersWakeupAtCommit(subid);
 
    return myself;
}
 
/*
 * Drop a subscription
 */
void
DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
{
    Relation    rel;
    ObjectAddress myself;
    HeapTuple   tup;
    Oid         subid;
    Oid         subowner;
    Datum       datum;
    bool        isnull;
    char       *subname;
    char       *conninfo;
    char       *slotname;
    List       *subworkers;
    ListCell   *lc;
    char        originname[NAMEDATALEN];
    char       *err = NULL;
    WalReceiverConn *wrconn = NULL;
    Form_pg_subscription form;
    List       *rstates;
    bool        must_use_password;
 
    /*
     * The launcher may concurrently start a new worker for this subscription.
     * During initialization, the worker checks for subscription validity and
     * exits if the subscription has already been dropped. See
     * InitializeLogRepWorker.
     */
    rel = table_open(SubscriptionRelationId, RowExclusiveLock);
 
    tup = SearchSysCache2(SUBSCRIPTIONNAME, ObjectIdGetDatum(MyDatabaseId),
                          CStringGetDatum(stmt->subname));
 
    if (!HeapTupleIsValid(tup))
    {
        table_close(rel, NoLock);
 
        if (!stmt->missing_ok)
            ereport(ERROR,
                    (errcode(ERRCODE_UNDEFINED_OBJECT),
                     errmsg("subscription \"%s\" does not exist",
                            stmt->subname)));
        else
            ereport(NOTICE,
                    (errmsg("subscription \"%s\" does not exist, skipping",
                            stmt->subname)));
 
        return;
    }
 
    form = (Form_pg_subscription) GETSTRUCT(tup);
    subid = form->oid;
    subowner = form->subowner;
    must_use_password = !superuser_arg(subowner) && form->subpasswordrequired;
 
    /* must be owner */
    if (!object_ownercheck(SubscriptionRelationId, subid, GetUserId()))
        aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
                       stmt->subname);
 
    /* DROP hook for the subscription being removed */
    InvokeObjectDropHook(SubscriptionRelationId, subid, 0);
 
    /*
     * Lock the subscription so nobody else can do anything with it (including
     * the replication workers).
     */
    LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
 
    /* Get subname */
    datum = SysCacheGetAttrNotNull(SUBSCRIPTIONOID, tup,
                                   Anum_pg_subscription_subname);
    subname = pstrdup(NameStr(*DatumGetName(datum)));
 
    /* Get conninfo */
    if (OidIsValid(form->subserver))
    {
        AclResult   aclresult;
        ForeignServer *server;
 
        server = GetForeignServer(form->subserver);
        aclresult = object_aclcheck(ForeignServerRelationId, form->subserver,
                                    form->subowner, ACL_USAGE);
        if (aclresult != ACLCHECK_OK)
        {
            /*
             * Unable to generate connection string because permissions on the
             * foreign server have been removed. Follow the same logic as an
             * unusable subconninfo (which will result in an ERROR later
             * unless slot_name = NONE).
             */
            err = psprintf(_("subscription owner \"%s\" does not have permission on foreign server \"%s\""),
                           GetUserNameFromId(form->subowner, false),
                           server->servername);
            conninfo = NULL;
        }
        else
            conninfo = ForeignServerConnectionString(form->subowner,
                                                     server);
    }
    else
    {
        datum = SysCacheGetAttrNotNull(SUBSCRIPTIONOID, tup,
                                       Anum_pg_subscription_subconninfo);
        conninfo = TextDatumGetCString(datum);
    }
 
    /* Get slotname */
    datum = SysCacheGetAttr(SUBSCRIPTIONOID, tup,
                            Anum_pg_subscription_subslotname, &isnull);
    if (!isnull)
        slotname = pstrdup(NameStr(*DatumGetName(datum)));
    else
        slotname = NULL;
 
    /*
     * Since dropping a replication slot is not transactional, the replication
     * slot stays dropped even if the transaction rolls back.  So we cannot
     * run DROP SUBSCRIPTION inside a transaction block if dropping the
     * replication slot.  Also, in this case, we report a message for dropping
     * the subscription to the cumulative stats system.
     *
     * XXX The command name should really be something like "DROP SUBSCRIPTION
     * of a subscription that is associated with a replication slot", but we
     * don't have the proper facilities for that.
     */
    if (slotname)
        PreventInTransactionBlock(isTopLevel, "DROP SUBSCRIPTION");
 
    ObjectAddressSet(myself, SubscriptionRelationId, subid);
    EventTriggerSQLDropAddObject(&myself, true, true);
 
    /* Remove the tuple from catalog. */
    CatalogTupleDelete(rel, &tup->t_self);
 
    ReleaseSysCache(tup);
 
    /*
     * Stop all the subscription workers immediately.
     *
     * This is necessary if we are dropping the replication slot, so that the
     * slot becomes accessible.
     *
     * It is also necessary if the subscription is disabled and was disabled
     * in the same transaction.  Then the workers haven't seen the disabling
     * yet and will still be running, leading to hangs later when we want to
     * drop the replication origin.  If the subscription was disabled before
     * this transaction, then there shouldn't be any workers left, so this
     * won't make a difference.
     *
     * New workers won't be started because we hold an exclusive lock on the
     * subscription till the end of the transaction.
     */
    subworkers = logicalrep_workers_find(subid, false, true);
    foreach(lc, subworkers)
    {
        LogicalRepWorker *w = (LogicalRepWorker *) lfirst(lc);
 
        logicalrep_worker_stop(w->type, w->subid, w->relid);
    }
    list_free(subworkers);
 
    /*
     * Remove the no-longer-useful entry in the launcher's table of apply
     * worker start times.
     *
     * If this transaction rolls back, the launcher might restart a failed
     * apply worker before wal_retrieve_retry_interval milliseconds have
     * elapsed, but that's pretty harmless.
     */
    ApplyLauncherForgetWorkerStartTime(subid);
 
    /*
     * Cleanup of tablesync replication origins.
     *
     * Any READY-state relations would already have dealt with clean-ups.
     *
     * Note that the state can't change because we have already stopped both
     * the apply and tablesync workers and they can't restart because of
     * exclusive lock on the subscription.
     */
    rstates = GetSubscriptionRelations(subid, true, false, true);
    foreach(lc, rstates)
    {
        SubscriptionRelState *rstate = (SubscriptionRelState *) lfirst(lc);
        Oid         relid = rstate->relid;
 
        /* Only cleanup resources of tablesync workers */
        if (!OidIsValid(relid))
            continue;
 
        /*
         * Drop the tablesync's origin tracking if exists.
         *
         * It is possible that the origin is not yet created for tablesync
         * worker so passing missing_ok = true. This can happen for the states
         * before SUBREL_STATE_DATASYNC.
         */
        ReplicationOriginNameForLogicalRep(subid, relid, originname,
                                           sizeof(originname));
        replorigin_drop_by_name(originname, true, false);
    }
 
    /* Clean up dependencies */
    deleteDependencyRecordsFor(SubscriptionRelationId, subid, false);
    deleteSharedDependencyRecordsFor(SubscriptionRelationId, subid, 0);
 
    /* Remove any associated relation synchronization states. */
    RemoveSubscriptionRel(subid, InvalidOid);
 
    /* Remove the origin tracking if exists. */
    ReplicationOriginNameForLogicalRep(subid, InvalidOid, originname, sizeof(originname));
    replorigin_drop_by_name(originname, true, false);
 
    /*
     * Tell the cumulative stats system that the subscription is getting
     * dropped.
     */
    pgstat_drop_subscription(subid);
 
    /*
     * If there is no slot associated with the subscription, we can finish
     * here.
     */
    if (!slotname && rstates == NIL)
    {
        table_close(rel, NoLock);
        return;
    }
 
    /*
     * Try to acquire the connection necessary for dropping slots.
     *
     * Note: If the slotname is NONE/NULL then we allow the command to finish
     * and users need to manually cleanup the apply and tablesync worker slots
     * later.
     *
     * This has to be at the end because otherwise if there is an error while
     * doing the database operations we won't be able to rollback dropped
     * slot.
     */
    load_file("libpqwalreceiver", false);
 
    if (conninfo)
        wrconn = walrcv_connect(conninfo, true, true, must_use_password,
                                subname, &err);
 
    if (wrconn == NULL)
    {
        if (!slotname)
        {
            /* be tidy */
            list_free(rstates);
            table_close(rel, NoLock);
            return;
        }
        else
        {
            ReportSlotConnectionError(rstates, subid, slotname, err);
        }
    }
 
    PG_TRY();
    {
        foreach(lc, rstates)
        {
            SubscriptionRelState *rstate = (SubscriptionRelState *) lfirst(lc);
            Oid         relid = rstate->relid;
 
            /* Only cleanup resources of tablesync workers */
            if (!OidIsValid(relid))
                continue;
 
            /*
             * Drop the tablesync slots associated with removed tables.
             *
             * For SYNCDONE/READY states, the tablesync slot is known to have
             * already been dropped by the tablesync worker.
             *
             * For other states, there is no certainty, maybe the slot does
             * not exist yet. Also, if we fail after removing some of the
             * slots, next time, it will again try to drop already dropped
             * slots and fail. For these reasons, we allow missing_ok = true
             * for the drop.
             */
            if (rstate->state != SUBREL_STATE_SYNCDONE)
            {
                char        syncslotname[NAMEDATALEN] = {0};
 
                ReplicationSlotNameForTablesync(subid, relid, syncslotname,
                                                sizeof(syncslotname));
                ReplicationSlotDropAtPubNode(wrconn, syncslotname, true);
            }
        }
 
        list_free(rstates);
 
        /*
         * If there is a slot associated with the subscription, then drop the
         * replication slot at the publisher.
         */
        if (slotname)
            ReplicationSlotDropAtPubNode(wrconn, slotname, false);
    }
    PG_FINALLY();
    {
        walrcv_disconnect(wrconn);
    }
    PG_END_TRY();
 
    table_close(rel, NoLock);
}
 
/*
 * Drop the replication slot at the publisher node using the replication
 * connection.
 *
 * missing_ok - if true then only issue a LOG message if the slot doesn't
 * exist.
 */
void
ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname, bool missing_ok)
{
    StringInfoData cmd;
 
    Assert(wrconn);
 
    load_file("libpqwalreceiver", false);
 
    initStringInfo(&cmd);
    appendStringInfo(&cmd, "DROP_REPLICATION_SLOT %s WAIT", quote_identifier(slotname));
 
    PG_TRY();
    {
        WalRcvExecResult *res;
 
        res = walrcv_exec(wrconn, cmd.data, 0, NULL);
 
        if (res->status == WALRCV_OK_COMMAND)
        {
            /* NOTICE. Success. */
            ereport(NOTICE,
                    (errmsg("dropped replication slot \"%s\" on publisher",
                            slotname)));
        }
        else if (res->status == WALRCV_ERROR &&
                 missing_ok &&
                 res->sqlstate == ERRCODE_UNDEFINED_OBJECT)
        {
            /* LOG. Error, but missing_ok = true. */
            ereport(LOG,
                    (errmsg("could not drop replication slot \"%s\" on publisher: %s",
                            slotname, res->err)));
        }
        else
        {
            /* ERROR. */
            ereport(ERROR,
                    (errcode(ERRCODE_CONNECTION_FAILURE),
                     errmsg("could not drop replication slot \"%s\" on publisher: %s",
                            slotname, res->err)));
        }
 
        walrcv_clear_result(res);
    }
    PG_FINALLY();
    {
        pfree(cmd.data);
    }
    PG_END_TRY();
}
 
/*
 * Internal workhorse for changing a subscription owner
 */
static void
AlterSubscriptionOwner_internal(Relation rel, HeapTuple tup, Oid newOwnerId)
{
    Form_pg_subscription form;
    AclResult   aclresult;
 
    form = (Form_pg_subscription) GETSTRUCT(tup);
 
    if (form->subowner == newOwnerId)
        return;
 
    if (!object_ownercheck(SubscriptionRelationId, form->oid, GetUserId()))
        aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
                       NameStr(form->subname));
 
    /*
     * Don't allow non-superuser modification of a subscription with
     * password_required=false.
     */
    if (!form->subpasswordrequired && !superuser())
        ereport(ERROR,
                (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                 errmsg("password_required=false is superuser-only"),
                 errhint("Subscriptions with the password_required option set to false may only be created or modified by the superuser.")));
 
    /* Must be able to become new owner */
    check_can_set_role(GetUserId(), newOwnerId);
 
    /*
     * current owner must have CREATE on database
     *
     * This is consistent with how ALTER SCHEMA ... OWNER TO works, but some
     * other object types behave differently (e.g. you can't give a table to a
     * user who lacks CREATE privileges on a schema).
     */
    aclresult = object_aclcheck(DatabaseRelationId, MyDatabaseId,
                                GetUserId(), ACL_CREATE);
    if (aclresult != ACLCHECK_OK)
        aclcheck_error(aclresult, OBJECT_DATABASE,
                       get_database_name(MyDatabaseId));
 
    /*
     * If the subscription uses a server, check that the new owner has USAGE
     * privileges on the server and that a user mapping exists. Note: does not
     * re-check the resulting connection string.
     */
    if (OidIsValid(form->subserver))
    {
        ForeignServer *server = GetForeignServer(form->subserver);
 
        aclresult = object_aclcheck(ForeignServerRelationId, server->serverid, newOwnerId, ACL_USAGE);
        if (aclresult != ACLCHECK_OK)
            ereport(ERROR,
                    errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                    errmsg("new subscription owner \"%s\" does not have permission on foreign server \"%s\"",
                           GetUserNameFromId(newOwnerId, false),
                           server->servername));
 
        /* make sure a user mapping exists */
        GetUserMapping(newOwnerId, server->serverid);
    }
 
    form->subowner = newOwnerId;
    CatalogTupleUpdate(rel, &tup->t_self, tup);
 
    /* Update owner dependency reference */
    changeDependencyOnOwner(SubscriptionRelationId,
                            form->oid,
                            newOwnerId);
 
    InvokeObjectPostAlterHook(SubscriptionRelationId,
                              form->oid, 0);
 
    /* Wake up related background processes to handle this change quickly. */
    ApplyLauncherWakeupAtCommit();
    LogicalRepWorkersWakeupAtCommit(form->oid);
}
 
/*
 * Change subscription owner -- by name
 */
ObjectAddress
AlterSubscriptionOwner(const char *name, Oid newOwnerId)
{
    Oid         subid;
    HeapTuple   tup;
    Relation    rel;
    ObjectAddress address;
    Form_pg_subscription form;
 
    rel = table_open(SubscriptionRelationId, RowExclusiveLock);
 
    tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME, ObjectIdGetDatum(MyDatabaseId),
                              CStringGetDatum(name));
 
    if (!HeapTupleIsValid(tup))
        ereport(ERROR,
                (errcode(ERRCODE_UNDEFINED_OBJECT),
                 errmsg("subscription \"%s\" does not exist", name)));
 
    form = (Form_pg_subscription) GETSTRUCT(tup);
    subid = form->oid;
 
    AlterSubscriptionOwner_internal(rel, tup, newOwnerId);
 
    ObjectAddressSet(address, SubscriptionRelationId, subid);
 
    heap_freetuple(tup);
 
    table_close(rel, RowExclusiveLock);
 
    return address;
}
 
/*
 * Change subscription owner -- by OID
 */
void
AlterSubscriptionOwner_oid(Oid subid, Oid newOwnerId)
{
    HeapTuple   tup;
    Relation    rel;
 
    rel = table_open(SubscriptionRelationId, RowExclusiveLock);
 
    tup = SearchSysCacheCopy1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
 
    if (!HeapTupleIsValid(tup))
        ereport(ERROR,
                (errcode(ERRCODE_UNDEFINED_OBJECT),
                 errmsg("subscription with OID %u does not exist", subid)));
 
    AlterSubscriptionOwner_internal(rel, tup, newOwnerId);
 
    heap_freetuple(tup);
 
    table_close(rel, RowExclusiveLock);
}
 
/*
 * Check and log a warning if the publisher has subscribed to the same table,
 * its partition ancestors (if it's a partition), or its partition children (if
 * it's a partitioned table), from some other publishers. This check is
 * required in the following scenarios:
 *
 * 1) For CREATE SUBSCRIPTION and ALTER SUBSCRIPTION ... REFRESH PUBLICATION
 *    statements with "copy_data = true" and "origin = none":
 *    - Warn the user that data with an origin might have been copied.
 *    - This check is skipped for tables already added, as incremental sync via
 *      WAL allows origin tracking. The list of such tables is in
 *      subrel_local_oids.
 *
 * 2) For CREATE SUBSCRIPTION and ALTER SUBSCRIPTION ... REFRESH PUBLICATION
 *    statements with "retain_dead_tuples = true" and "origin = any", and for
 *    ALTER SUBSCRIPTION statements that modify retain_dead_tuples or origin,
 *    or when the publisher's status changes (e.g., due to a connection string
 *    update):
 *    - Warn the user that only conflict detection info for local changes on
 *      the publisher is retained. Data from other origins may lack sufficient
 *      details for reliable conflict detection.
 *    - See comments atop worker.c for more details.
 */
static void
check_publications_origin_tables(WalReceiverConn *wrconn, List *publications,
                                 bool copydata, bool retain_dead_tuples,
                                 char *origin, Oid *subrel_local_oids,
                                 int subrel_count, char *subname)
{
    WalRcvExecResult *res;
    StringInfoData cmd;
    TupleTableSlot *slot;
    Oid         tableRow[1] = {TEXTOID};
    List       *publist = NIL;
    int         i;
    bool        check_rdt;
    bool        check_table_sync;
    bool        origin_none = origin &&
        pg_strcasecmp(origin, LOGICALREP_ORIGIN_NONE) == 0;
 
    /*
     * Enable retain_dead_tuples checks only when origin is set to 'any',
     * since with origin='none' only local changes are replicated to the
     * subscriber.
     */
    check_rdt = retain_dead_tuples && !origin_none;
 
    /*
     * Enable table synchronization checks only when origin is 'none', to
     * ensure that data from other origins is not inadvertently copied.
     */
    check_table_sync = copydata && origin_none;
 
    /* retain_dead_tuples and table sync checks occur separately */
    Assert(!(check_rdt && check_table_sync));
 
    /* Return if no checks are required */
    if (!check_rdt && !check_table_sync)
        return;
 
    initStringInfo(&cmd);
    appendStringInfoString(&cmd,
                           "SELECT DISTINCT P.pubname AS pubname\n"
                           "FROM pg_publication P,\n"
                           "     LATERAL pg_get_publication_tables(P.pubname) GPT\n"
                           "     JOIN pg_subscription_rel PS ON (GPT.relid = PS.srrelid OR"
                           "     GPT.relid IN (SELECT relid FROM pg_partition_ancestors(PS.srrelid) UNION"
                           "                   SELECT relid FROM pg_partition_tree(PS.srrelid))),\n"
                           "     pg_class C JOIN pg_namespace N ON (N.oid = C.relnamespace)\n"
                           "WHERE C.oid = GPT.relid AND P.pubname IN (");
    GetPublicationsStr(publications, &cmd, true);
    appendStringInfoString(&cmd, ")\n");
 
    /*
     * In case of ALTER SUBSCRIPTION ... REFRESH PUBLICATION,
     * subrel_local_oids contains the list of relation oids that are already
     * present on the subscriber. This check should be skipped for these
     * tables if checking for table sync scenario. However, when handling the
     * retain_dead_tuples scenario, ensure all tables are checked, as some
     * existing tables may now include changes from other origins due to newly
     * created subscriptions on the publisher.
     */
    if (check_table_sync)
    {
        for (i = 0; i < subrel_count; i++)
        {
            Oid         relid = subrel_local_oids[i];
            char       *schemaname = get_namespace_name(get_rel_namespace(relid));
            char       *tablename = get_rel_name(relid);
 
            appendStringInfo(&cmd, "AND NOT (N.nspname = '%s' AND C.relname = '%s')\n",
                             schemaname, tablename);
        }
    }
 
    res = walrcv_exec(wrconn, cmd.data, 1, tableRow);
    pfree(cmd.data);
 
    if (res->status != WALRCV_OK_TUPLES)
        ereport(ERROR,
                (errcode(ERRCODE_CONNECTION_FAILURE),
                 errmsg("could not receive list of replicated tables from the publisher: %s",
                        res->err)));
 
    /* Process publications. */
    slot = MakeSingleTupleTableSlot(res->tupledesc, &TTSOpsMinimalTuple);
    while (tuplestore_gettupleslot(res->tuplestore, true, false, slot))
    {
        char       *pubname;
        bool        isnull;
 
        pubname = TextDatumGetCString(slot_getattr(slot, 1, &isnull));
        Assert(!isnull);
 
        ExecClearTuple(slot);
        publist = list_append_unique(publist, makeString(pubname));
    }
 
    /*
     * Log a warning if the publisher has subscribed to the same table from
     * some other publisher. We cannot know the origin of data during the
     * initial sync. Data origins can be found only from the WAL by looking at
     * the origin id.
     *
     * XXX: For simplicity, we don't check whether the table has any data or
     * not. If the table doesn't have any data then we don't need to
     * distinguish between data having origin and data not having origin so we
     * can avoid logging a warning for table sync scenario.
     */
    if (publist)
    {
        StringInfoData pubnames;
 
        /* Prepare the list of publication(s) for warning message. */
        initStringInfo(&pubnames);
        GetPublicationsStr(publist, &pubnames, false);
 
        if (check_table_sync)
            ereport(WARNING,
                    errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                    errmsg("subscription \"%s\" requested copy_data with origin = NONE but might copy data that had a different origin",
                           subname),
                    errdetail_plural("The subscription subscribes to a publication (%s) that contains tables that are written to by other subscriptions.",
                                     "The subscription subscribes to publications (%s) that contain tables that are written to by other subscriptions.",
                                     list_length(publist), pubnames.data),
                    errhint("Verify that initial data copied from the publisher tables did not come from other origins."));
        else
            ereport(WARNING,
                    errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                    errmsg("subscription \"%s\" enabled retain_dead_tuples but might not reliably detect conflicts for changes from different origins",
                           subname),
                    errdetail_plural("The subscription subscribes to a publication (%s) that contains tables that are written to by other subscriptions.",
                                     "The subscription subscribes to publications (%s) that contain tables that are written to by other subscriptions.",
                                     list_length(publist), pubnames.data),
                    errhint("Consider using origin = NONE or disabling retain_dead_tuples."));
    }
 
    ExecDropSingleTupleTableSlot(slot);
 
    walrcv_clear_result(res);
}
 
/*
 * This function is similar to check_publications_origin_tables and serves
 * same purpose for sequences.
 */
static void
check_publications_origin_sequences(WalReceiverConn *wrconn, List *publications,
                                    bool copydata, char *origin,
                                    Oid *subrel_local_oids, int subrel_count,
                                    char *subname)
{
    WalRcvExecResult *res;
    StringInfoData cmd;
    TupleTableSlot *slot;
    Oid         tableRow[1] = {TEXTOID};
    List       *publist = NIL;
 
    /*
     * Enable sequence synchronization checks only when origin is 'none' , to
     * ensure that sequence data from other origins is not inadvertently
     * copied. This check is necessary if the publisher is running PG19 or
     * later, where logical replication sequence synchronization is supported.
     */
    if (!copydata || pg_strcasecmp(origin, LOGICALREP_ORIGIN_NONE) != 0 ||
        walrcv_server_version(wrconn) < 190000)
        return;
 
    initStringInfo(&cmd);
    appendStringInfoString(&cmd,
                           "SELECT DISTINCT P.pubname AS pubname\n"
                           "FROM pg_publication P,\n"
                           "     LATERAL pg_get_publication_sequences(P.pubname) GPS\n"
                           "     JOIN pg_subscription_rel PS ON (GPS.relid = PS.srrelid),\n"
                           "     pg_class C JOIN pg_namespace N ON (N.oid = C.relnamespace)\n"
                           "WHERE C.oid = GPS.relid AND P.pubname IN (");
 
    GetPublicationsStr(publications, &cmd, true);
    appendStringInfoString(&cmd, ")\n");
 
    /*
     * In case of ALTER SUBSCRIPTION ... REFRESH PUBLICATION,
     * subrel_local_oids contains the list of relations that are already
     * present on the subscriber. This check should be skipped as these will
     * not be re-synced.
     */
    for (int i = 0; i < subrel_count; i++)
    {
        Oid         relid = subrel_local_oids[i];
        char       *schemaname = get_namespace_name(get_rel_namespace(relid));
        char       *seqname = get_rel_name(relid);
 
        appendStringInfo(&cmd,
                         "AND NOT (N.nspname = '%s' AND C.relname = '%s')\n",
                         schemaname, seqname);
    }
 
    res = walrcv_exec(wrconn, cmd.data, 1, tableRow);
    pfree(cmd.data);
 
    if (res->status != WALRCV_OK_TUPLES)
        ereport(ERROR,
                (errcode(ERRCODE_CONNECTION_FAILURE),
                 errmsg("could not receive list of replicated sequences from the publisher: %s",
                        res->err)));
 
    /* Process publications. */
    slot = MakeSingleTupleTableSlot(res->tupledesc, &TTSOpsMinimalTuple);
    while (tuplestore_gettupleslot(res->tuplestore, true, false, slot))
    {
        char       *pubname;
        bool        isnull;
 
        pubname = TextDatumGetCString(slot_getattr(slot, 1, &isnull));
        Assert(!isnull);
 
        ExecClearTuple(slot);
        publist = list_append_unique(publist, makeString(pubname));
    }
 
    /*
     * Log a warning if the publisher has subscribed to the same sequence from
     * some other publisher. We cannot know the origin of sequences data
     * during the initial sync.
     */
    if (publist)
    {
        StringInfoData pubnames;
 
        /* Prepare the list of publication(s) for warning message. */
        initStringInfo(&pubnames);
        GetPublicationsStr(publist, &pubnames, false);
 
        ereport(WARNING,
                errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                errmsg("subscription \"%s\" requested copy_data with origin = NONE but might copy data that had a different origin",
                       subname),
                errdetail_plural("The subscription subscribes to a publication (%s) that contains sequences that are written to by other subscriptions.",
                                 "The subscription subscribes to publications (%s) that contain sequences that are written to by other subscriptions.",
                                 list_length(publist), pubnames.data),
                errhint("Verify that initial data copied from the publisher sequences did not come from other origins."));
    }
 
    ExecDropSingleTupleTableSlot(slot);
 
    walrcv_clear_result(res);
}
 
/*
 * Determine whether the retain_dead_tuples can be enabled based on the
 * publisher's status.
 *
 * This option is disallowed if the publisher is running a version earlier
 * than the PG19, or if the publisher is in recovery (i.e., it is a standby
 * server).
 *
 * See comments atop worker.c for a detailed explanation.
 */
static void
check_pub_dead_tuple_retention(WalReceiverConn *wrconn)
{
    WalRcvExecResult *res;
    Oid         RecoveryRow[1] = {BOOLOID};
    TupleTableSlot *slot;
    bool        isnull;
    bool        remote_in_recovery;
 
    if (walrcv_server_version(wrconn) < 190000)
        ereport(ERROR,
                errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                errmsg("cannot enable retain_dead_tuples if the publisher is running a version earlier than PostgreSQL 19"));
 
    res = walrcv_exec(wrconn, "SELECT pg_is_in_recovery()", 1, RecoveryRow);
 
    if (res->status != WALRCV_OK_TUPLES)
        ereport(ERROR,
                (errcode(ERRCODE_CONNECTION_FAILURE),
                 errmsg("could not obtain recovery progress from the publisher: %s",
                        res->err)));
 
    slot = MakeSingleTupleTableSlot(res->tupledesc, &TTSOpsMinimalTuple);
    if (!tuplestore_gettupleslot(res->tuplestore, true, false, slot))
        elog(ERROR, "failed to fetch tuple for the recovery progress");
 
    remote_in_recovery = DatumGetBool(slot_getattr(slot, 1, &isnull));
 
    if (remote_in_recovery)
        ereport(ERROR,
                errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                errmsg("cannot enable retain_dead_tuples if the publisher is in recovery"));
 
    ExecDropSingleTupleTableSlot(slot);
 
    walrcv_clear_result(res);
}
 
/*
 * Check if the subscriber's configuration is adequate to enable the
 * retain_dead_tuples option.
 *
 * Issue an ERROR if the wal_level does not support the use of replication
 * slots when check_guc is set to true.
 *
 * Issue a WARNING if track_commit_timestamp is not enabled when check_guc is
 * set to true. This is only to highlight the importance of enabling
 * track_commit_timestamp instead of catching all the misconfigurations, as
 * this setting can be adjusted after subscription creation. Without it, the
 * apply worker will simply skip conflict detection.
 *
 * Issue a WARNING or NOTICE if the subscription is disabled and the retention
 * is active. Do not raise an ERROR since users can only modify
 * retain_dead_tuples for disabled subscriptions. And as long as the
 * subscription is enabled promptly, it will not pose issues.
 *
 * Issue a NOTICE to inform users that max_retention_duration is
 * ineffective when retain_dead_tuples is disabled for a subscription. An ERROR
 * is not issued because setting max_retention_duration causes no harm,
 * even when it is ineffective.
 */
void
CheckSubDeadTupleRetention(bool check_guc, bool sub_disabled,
                           int elevel_for_sub_disabled,
                           bool retain_dead_tuples, bool retention_active,
                           bool max_retention_set)
{
    Assert(elevel_for_sub_disabled == NOTICE ||
           elevel_for_sub_disabled == WARNING);
 
    if (retain_dead_tuples)
    {
        if (check_guc && wal_level < WAL_LEVEL_REPLICA)
            ereport(ERROR,
                    errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                    errmsg("\"wal_level\" is insufficient to create the replication slot required by retain_dead_tuples"),
                    errhint("\"wal_level\" must be set to \"replica\" or \"logical\" at server start."));
 
        if (check_guc && !track_commit_timestamp)
            ereport(WARNING,
                    errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                    errmsg("commit timestamp and origin data required for detecting conflicts won't be retained"),
                    errhint("Consider setting \"%s\" to true.",
                            "track_commit_timestamp"));
 
        if (sub_disabled && retention_active)
            ereport(elevel_for_sub_disabled,
                    errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                    errmsg("deleted rows to detect conflicts would not be removed until the subscription is enabled"),
                    (elevel_for_sub_disabled > NOTICE)
                    ? errhint("Consider setting %s to false.",
                              "retain_dead_tuples") : 0);
    }
    else if (max_retention_set)
    {
        ereport(NOTICE,
                errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                errmsg("max_retention_duration is ineffective when retain_dead_tuples is disabled"));
    }
}
 
/*
 * Return true iff 'rv' is a member of the list.
 */
static bool
list_member_rangevar(const List *list, RangeVar *rv)
{
    foreach_ptr(PublicationRelKind, relinfo, list)
    {
        if (equal(relinfo->rv, rv))
            return true;
    }
 
    return false;
}
 
/*
 * Get the list of tables and sequences which belong to specified publications
 * on the publisher connection.
 *
 * Note that we don't support the case where the column list is different for
 * the same table in different publications to avoid sending unwanted column
 * information for some of the rows. This can happen when both the column
 * list and row filter are specified for different publications.
 */
static List *
fetch_relation_list(WalReceiverConn *wrconn, List *publications)
{
    WalRcvExecResult *res;
    StringInfoData cmd;
    TupleTableSlot *slot;
    Oid         tableRow[4] = {TEXTOID, TEXTOID, CHAROID, InvalidOid};
    List       *relationlist = NIL;
    int         server_version = walrcv_server_version(wrconn);
    bool        check_columnlist = (server_version >= 150000);
    int         column_count = check_columnlist ? 4 : 3;
    StringInfoData pub_names;
 
    initStringInfo(&cmd);
    initStringInfo(&pub_names);
 
    /* Build the pub_names comma-separated string. */
    GetPublicationsStr(publications, &pub_names, true);
 
    /* Get the list of relations from the publisher */
    if (server_version >= 160000)
    {
        tableRow[3] = INT2VECTOROID;
 
        /*
         * From version 16, we allowed passing multiple publications to the
         * function pg_get_publication_tables. This helped to filter out the
         * partition table whose ancestor is also published in this
         * publication array.
         *
         * Join pg_get_publication_tables with pg_publication to exclude
         * non-existing publications.
         *
         * Note that attrs are always stored in sorted order so we don't need
         * to worry if different publications have specified them in a
         * different order. See pub_collist_validate.
         */
        appendStringInfo(&cmd, "SELECT DISTINCT n.nspname, c.relname, c.relkind, gpt.attrs\n"
                         "   FROM pg_class c\n"
                         "         JOIN pg_namespace n ON n.oid = c.relnamespace\n"
                         "         JOIN ( SELECT (pg_get_publication_tables(VARIADIC array_agg(pubname::text))).*\n"
                         "                FROM pg_publication\n"
                         "                WHERE pubname IN ( %s )) AS gpt\n"
                         "             ON gpt.relid = c.oid\n",
                         pub_names.data);
 
        /* From version 19, inclusion of sequences in the target is supported */
        if (server_version >= 190000)
            appendStringInfo(&cmd,
                             "UNION ALL\n"
                             "  SELECT DISTINCT s.schemaname, s.sequencename, " CppAsString2(RELKIND_SEQUENCE) "::\"char\" AS relkind, NULL::int2vector AS attrs\n"
                             "  FROM pg_catalog.pg_publication_sequences s\n"
                             "  WHERE s.pubname IN ( %s )",
                             pub_names.data);
    }
    else
    {
        tableRow[3] = NAMEARRAYOID;
        appendStringInfoString(&cmd, "SELECT DISTINCT t.schemaname, t.tablename, " CppAsString2(RELKIND_RELATION) "::\"char\" AS relkind \n");
 
        /* Get column lists for each relation if the publisher supports it */
        if (check_columnlist)
            appendStringInfoString(&cmd, ", t.attnames\n");
 
        appendStringInfo(&cmd, "FROM pg_catalog.pg_publication_tables t\n"
                         " WHERE t.pubname IN ( %s )",
                         pub_names.data);
    }
 
    pfree(pub_names.data);
 
    res = walrcv_exec(wrconn, cmd.data, column_count, tableRow);
    pfree(cmd.data);
 
    if (res->status != WALRCV_OK_TUPLES)
        ereport(ERROR,
                (errcode(ERRCODE_CONNECTION_FAILURE),
                 errmsg("could not receive list of replicated tables from the publisher: %s",
                        res->err)));
 
    /* Process tables. */
    slot = MakeSingleTupleTableSlot(res->tupledesc, &TTSOpsMinimalTuple);
    while (tuplestore_gettupleslot(res->tuplestore, true, false, slot))
    {
        char       *nspname;
        char       *relname;
        bool        isnull;
        char        relkind;
        PublicationRelKind *relinfo = palloc_object(PublicationRelKind);
 
        nspname = TextDatumGetCString(slot_getattr(slot, 1, &isnull));
        Assert(!isnull);
        relname = TextDatumGetCString(slot_getattr(slot, 2, &isnull));
        Assert(!isnull);
        relkind = DatumGetChar(slot_getattr(slot, 3, &isnull));
        Assert(!isnull);
 
        relinfo->rv = makeRangeVar(nspname, relname, -1);
        relinfo->relkind = relkind;
 
        if (relkind != RELKIND_SEQUENCE &&
            check_columnlist &&
            list_member_rangevar(relationlist, relinfo->rv))
            ereport(ERROR,
                    errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                    errmsg("cannot use different column lists for table \"%s.%s\" in different publications",
                           nspname, relname));
        else
            relationlist = lappend(relationlist, relinfo);
 
        ExecClearTuple(slot);
    }
    ExecDropSingleTupleTableSlot(slot);
 
    walrcv_clear_result(res);
 
    return relationlist;
}
 
/*
 * This is to report the connection failure while dropping replication slots.
 * Here, we report the WARNING for all tablesync slots so that user can drop
 * them manually, if required.
 */
static void
ReportSlotConnectionError(List *rstates, Oid subid, char *slotname, char *err)
{
    ListCell   *lc;
 
    foreach(lc, rstates)
    {
        SubscriptionRelState *rstate = (SubscriptionRelState *) lfirst(lc);
        Oid         relid = rstate->relid;
 
        /* Only cleanup resources of tablesync workers */
        if (!OidIsValid(relid))
            continue;
 
        /*
         * Caller needs to ensure that relstate doesn't change underneath us.
         * See DropSubscription where we get the relstates.
         */
        if (rstate->state != SUBREL_STATE_SYNCDONE)
        {
            char        syncslotname[NAMEDATALEN] = {0};
 
            ReplicationSlotNameForTablesync(subid, relid, syncslotname,
                                            sizeof(syncslotname));
            elog(WARNING, "could not drop tablesync replication slot \"%s\"",
                 syncslotname);
        }
    }
 
    ereport(ERROR,
            (errcode(ERRCODE_CONNECTION_FAILURE),
             errmsg("could not connect to publisher when attempting to drop replication slot \"%s\": %s",
                    slotname, err),
    /* translator: %s is an SQL ALTER command */
             errhint("Use %s to disable the subscription, and then use %s to disassociate it from the slot.",
                     "ALTER SUBSCRIPTION ... DISABLE",
                     "ALTER SUBSCRIPTION ... SET (slot_name = NONE)")));
}
 
/*
 * Check for duplicates in the given list of publications and error out if
 * found one.  Add publications to datums as text datums, if datums is not
 * NULL.
 */
static void
check_duplicates_in_publist(List *publist, Datum *datums)
{
    ListCell   *cell;
    int         j = 0;
 
    foreach(cell, publist)
    {
        char       *name = strVal(lfirst(cell));
        ListCell   *pcell;
 
        foreach(pcell, publist)
        {
            char       *pname = strVal(lfirst(pcell));
 
            if (pcell == cell)
                break;
 
            if (strcmp(name, pname) == 0)
                ereport(ERROR,
                        (errcode(ERRCODE_DUPLICATE_OBJECT),
                         errmsg("publication name \"%s\" used more than once",
                                pname)));
        }
 
        if (datums)
            datums[j++] = CStringGetTextDatum(name);
    }
}
 
/*
 * Merge current subscription's publications and user-specified publications
 * from ADD/DROP PUBLICATIONS.
 *
 * If addpub is true, we will add the list of publications into oldpublist.
 * Otherwise, we will delete the list of publications from oldpublist.  The
 * returned list is a copy, oldpublist itself is not changed.
 *
 * subname is the subscription name, for error messages.
 */
static List *
merge_publications(List *oldpublist, List *newpublist, bool addpub, const char *subname)
{
    ListCell   *lc;
 
    oldpublist = list_copy(oldpublist);
 
    check_duplicates_in_publist(newpublist, NULL);
 
    foreach(lc, newpublist)
    {
        char       *name = strVal(lfirst(lc));
        ListCell   *lc2;
        bool        found = false;
 
        foreach(lc2, oldpublist)
        {
            char       *pubname = strVal(lfirst(lc2));
 
            if (strcmp(name, pubname) == 0)
            {
                found = true;
                if (addpub)
                    ereport(ERROR,
                            (errcode(ERRCODE_DUPLICATE_OBJECT),
                             errmsg("publication \"%s\" is already in subscription \"%s\"",
                                    name, subname)));
                else
                    oldpublist = foreach_delete_current(oldpublist, lc2);
 
                break;
            }
        }
 
        if (addpub && !found)
            oldpublist = lappend(oldpublist, makeString(name));
        else if (!addpub && !found)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                     errmsg("publication \"%s\" is not in subscription \"%s\"",
                            name, subname)));
    }
 
    /*
     * XXX Probably no strong reason for this, but for now it's to make ALTER
     * SUBSCRIPTION ... DROP PUBLICATION consistent with SET PUBLICATION.
     */
    if (!oldpublist)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                 errmsg("cannot drop all the publications from a subscription")));
 
    return oldpublist;
}
 
/*
 * Extract the streaming mode value from a DefElem.  This is like
 * defGetBoolean() but also accepts the special value of "parallel".
 */
char
defGetStreamingMode(DefElem *def)
{
    /*
     * If no parameter value given, assume "true" is meant.
     */
    if (!def->arg)
        return LOGICALREP_STREAM_ON;
 
    /*
     * Allow 0, 1, "false", "true", "off", "on" or "parallel".
     */
    switch (nodeTag(def->arg))
    {
        case T_Integer:
            switch (intVal(def->arg))
            {
                case 0:
                    return LOGICALREP_STREAM_OFF;
                case 1:
                    return LOGICALREP_STREAM_ON;
                default:
                    /* otherwise, error out below */
                    break;
            }
            break;
        default:
            {
                char       *sval = defGetString(def);
 
                /*
                 * The set of strings accepted here should match up with the
                 * grammar's opt_boolean_or_string production.
                 */
                if (pg_strcasecmp(sval, "false") == 0 ||
                    pg_strcasecmp(sval, "off") == 0)
                    return LOGICALREP_STREAM_OFF;
                if (pg_strcasecmp(sval, "true") == 0 ||
                    pg_strcasecmp(sval, "on") == 0)
                    return LOGICALREP_STREAM_ON;
                if (pg_strcasecmp(sval, "parallel") == 0)
                    return LOGICALREP_STREAM_PARALLEL;
            }
            break;
    }
 
    ereport(ERROR,
            (errcode(ERRCODE_SYNTAX_ERROR),
             errmsg("%s requires a Boolean value or \"parallel\"",
                    def->defname)));
    return LOGICALREP_STREAM_OFF;   /* keep compiler quiet */
}