alter.c

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/*-------------------------------------------------------------------------
 *
 * alter.c
 *    Drivers for generic alter commands
 *
 * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *    src/backend/commands/alter.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include "access/htup_details.h"
#include "access/relation.h"
#include "access/sysattr.h"
#include "access/table.h"
#include "catalog/dependency.h"
#include "catalog/indexing.h"
#include "catalog/namespace.h"
#include "catalog/objectaccess.h"
#include "catalog/pg_collation.h"
#include "catalog/pg_conversion.h"
#include "catalog/pg_event_trigger.h"
#include "catalog/pg_foreign_data_wrapper.h"
#include "catalog/pg_foreign_server.h"
#include "catalog/pg_language.h"
#include "catalog/pg_largeobject.h"
#include "catalog/pg_largeobject_metadata.h"
#include "catalog/pg_namespace.h"
#include "catalog/pg_opclass.h"
#include "catalog/pg_opfamily.h"
#include "catalog/pg_proc.h"
#include "catalog/pg_statistic_ext.h"
#include "catalog/pg_subscription.h"
#include "catalog/pg_ts_config.h"
#include "catalog/pg_ts_dict.h"
#include "catalog/pg_ts_parser.h"
#include "catalog/pg_ts_template.h"
#include "commands/alter.h"
#include "commands/collationcmds.h"
#include "commands/conversioncmds.h"
#include "commands/dbcommands.h"
#include "commands/defrem.h"
#include "commands/event_trigger.h"
#include "commands/extension.h"
#include "commands/policy.h"
#include "commands/proclang.h"
#include "commands/publicationcmds.h"
#include "commands/schemacmds.h"
#include "commands/subscriptioncmds.h"
#include "commands/tablecmds.h"
#include "commands/tablespace.h"
#include "commands/trigger.h"
#include "commands/typecmds.h"
#include "commands/user.h"
#include "miscadmin.h"
#include "parser/parse_func.h"
#include "rewrite/rewriteDefine.h"
#include "tcop/utility.h"
#include "utils/builtins.h"
#include "utils/fmgroids.h"
#include "utils/lsyscache.h"
#include "utils/rel.h"
#include "utils/syscache.h"

static Oid  AlterObjectNamespace_internal(Relation rel, Oid objid, Oid nspOid);

/*
 * Raise an error to the effect that an object of the given name is already
 * present in the given namespace.
 */
static void
report_name_conflict(Oid classId, const char *name)
{
    char       *msgfmt;

    switch (classId)
    {
        case EventTriggerRelationId:
            msgfmt = gettext_noop("event trigger \"%s\" already exists");
            break;
        case ForeignDataWrapperRelationId:
            msgfmt = gettext_noop("foreign-data wrapper \"%s\" already exists");
            break;
        case ForeignServerRelationId:
            msgfmt = gettext_noop("server \"%s\" already exists");
            break;
        case LanguageRelationId:
            msgfmt = gettext_noop("language \"%s\" already exists");
            break;
        case PublicationRelationId:
            msgfmt = gettext_noop("publication \"%s\" already exists");
            break;
        case SubscriptionRelationId:
            msgfmt = gettext_noop("subscription \"%s\" already exists");
            break;
        default:
            elog(ERROR, "unsupported object class %u", classId);
            break;
    }

    ereport(ERROR,
            (errcode(ERRCODE_DUPLICATE_OBJECT),
             errmsg(msgfmt, name)));
}

static void
report_namespace_conflict(Oid classId, const char *name, Oid nspOid)
{
    char       *msgfmt;

    Assert(OidIsValid(nspOid));

    switch (classId)
    {
        case ConversionRelationId:
            Assert(OidIsValid(nspOid));
            msgfmt = gettext_noop("conversion \"%s\" already exists in schema \"%s\"");
            break;
        case StatisticExtRelationId:
            Assert(OidIsValid(nspOid));
            msgfmt = gettext_noop("statistics object \"%s\" already exists in schema \"%s\"");
            break;
        case TSParserRelationId:
            Assert(OidIsValid(nspOid));
            msgfmt = gettext_noop("text search parser \"%s\" already exists in schema \"%s\"");
            break;
        case TSDictionaryRelationId:
            Assert(OidIsValid(nspOid));
            msgfmt = gettext_noop("text search dictionary \"%s\" already exists in schema \"%s\"");
            break;
        case TSTemplateRelationId:
            Assert(OidIsValid(nspOid));
            msgfmt = gettext_noop("text search template \"%s\" already exists in schema \"%s\"");
            break;
        case TSConfigRelationId:
            Assert(OidIsValid(nspOid));
            msgfmt = gettext_noop("text search configuration \"%s\" already exists in schema \"%s\"");
            break;
        default:
            elog(ERROR, "unsupported object class %u", classId);
            break;
    }

    ereport(ERROR,
            (errcode(ERRCODE_DUPLICATE_OBJECT),
             errmsg(msgfmt, name, get_namespace_name(nspOid))));
}

/*
 * AlterObjectRename_internal
 *
 * Generic function to rename the given object, for simple cases (won't
 * work for tables, nor other cases where we need to do more than change
 * the name column of a single catalog entry).
 *
 * rel: catalog relation containing object (RowExclusiveLock'd by caller)
 * objectId: OID of object to be renamed
 * new_name: CString representation of new name
 */
static void
AlterObjectRename_internal(Relation rel, Oid objectId, const char *new_name)
{
    Oid         classId = RelationGetRelid(rel);
    int         oidCacheId = get_object_catcache_oid(classId);
    int         nameCacheId = get_object_catcache_name(classId);
    AttrNumber  Anum_name = get_object_attnum_name(classId);
    AttrNumber  Anum_namespace = get_object_attnum_namespace(classId);
    AttrNumber  Anum_owner = get_object_attnum_owner(classId);
    HeapTuple   oldtup;
    HeapTuple   newtup;
    Datum       datum;
    bool        isnull;
    Oid         namespaceId;
    Oid         ownerId;
    char       *old_name;
    AclResult   aclresult;
    Datum      *values;
    bool       *nulls;
    bool       *replaces;
    NameData    nameattrdata;

    oldtup = SearchSysCache1(oidCacheId, ObjectIdGetDatum(objectId));
    if (!HeapTupleIsValid(oldtup))
        elog(ERROR, "cache lookup failed for object %u of catalog \"%s\"",
             objectId, RelationGetRelationName(rel));

    datum = heap_getattr(oldtup, Anum_name,
                         RelationGetDescr(rel), &isnull);
    Assert(!isnull);
    old_name = NameStr(*(DatumGetName(datum)));

    /* Get OID of namespace */
    if (Anum_namespace > 0)
    {
        datum = heap_getattr(oldtup, Anum_namespace,
                             RelationGetDescr(rel), &isnull);
        Assert(!isnull);
        namespaceId = DatumGetObjectId(datum);
    }
    else
        namespaceId = InvalidOid;

    /* Permission checks ... superusers can always do it */
    if (!superuser())
    {
        /* Fail if object does not have an explicit owner */
        if (Anum_owner <= 0)
            ereport(ERROR,
                    (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                     (errmsg("must be superuser to rename %s",
                             getObjectDescriptionOids(classId, objectId)))));

        /* Otherwise, must be owner of the existing object */
        datum = heap_getattr(oldtup, Anum_owner,
                             RelationGetDescr(rel), &isnull);
        Assert(!isnull);
        ownerId = DatumGetObjectId(datum);

        if (!has_privs_of_role(GetUserId(), DatumGetObjectId(ownerId)))
            aclcheck_error(ACLCHECK_NOT_OWNER, get_object_type(classId, objectId),
                           old_name);

        /* User must have CREATE privilege on the namespace */
        if (OidIsValid(namespaceId))
        {
            aclresult = pg_namespace_aclcheck(namespaceId, GetUserId(),
                                              ACL_CREATE);
            if (aclresult != ACLCHECK_OK)
                aclcheck_error(aclresult, OBJECT_SCHEMA,
                               get_namespace_name(namespaceId));
        }
    }

    /*
     * Check for duplicate name (more friendly than unique-index failure).
     * Since this is just a friendliness check, we can just skip it in cases
     * where there isn't suitable support.
     */
    if (classId == ProcedureRelationId)
    {
        Form_pg_proc proc = (Form_pg_proc) GETSTRUCT(oldtup);

        IsThereFunctionInNamespace(new_name, proc->pronargs,
                                   &proc->proargtypes, proc->pronamespace);
    }
    else if (classId == CollationRelationId)
    {
        Form_pg_collation coll = (Form_pg_collation) GETSTRUCT(oldtup);

        IsThereCollationInNamespace(new_name, coll->collnamespace);
    }
    else if (classId == OperatorClassRelationId)
    {
        Form_pg_opclass opc = (Form_pg_opclass) GETSTRUCT(oldtup);

        IsThereOpClassInNamespace(new_name, opc->opcmethod,
                                  opc->opcnamespace);
    }
    else if (classId == OperatorFamilyRelationId)
    {
        Form_pg_opfamily opf = (Form_pg_opfamily) GETSTRUCT(oldtup);

        IsThereOpFamilyInNamespace(new_name, opf->opfmethod,
                                   opf->opfnamespace);
    }
    else if (classId == SubscriptionRelationId)
    {
        if (SearchSysCacheExists2(SUBSCRIPTIONNAME, MyDatabaseId,
                                  CStringGetDatum(new_name)))
            report_name_conflict(classId, new_name);

        /* Also enforce regression testing naming rules, if enabled */
#ifdef ENFORCE_REGRESSION_TEST_NAME_RESTRICTIONS
        if (strncmp(new_name, "regress_", 8) != 0)
            elog(WARNING, "subscriptions created by regression test cases should have names starting with \"regress_\"");
#endif
    }
    else if (nameCacheId >= 0)
    {
        if (OidIsValid(namespaceId))
        {
            if (SearchSysCacheExists2(nameCacheId,
                                      CStringGetDatum(new_name),
                                      ObjectIdGetDatum(namespaceId)))
                report_namespace_conflict(classId, new_name, namespaceId);
        }
        else
        {
            if (SearchSysCacheExists1(nameCacheId,
                                      CStringGetDatum(new_name)))
                report_name_conflict(classId, new_name);
        }
    }

    /* Build modified tuple */
    values = palloc0(RelationGetNumberOfAttributes(rel) * sizeof(Datum));
    nulls = palloc0(RelationGetNumberOfAttributes(rel) * sizeof(bool));
    replaces = palloc0(RelationGetNumberOfAttributes(rel) * sizeof(bool));
    namestrcpy(&nameattrdata, new_name);
    values[Anum_name - 1] = NameGetDatum(&nameattrdata);
    replaces[Anum_name - 1] = true;
    newtup = heap_modify_tuple(oldtup, RelationGetDescr(rel),
                               values, nulls, replaces);

    /* Perform actual update */
    CatalogTupleUpdate(rel, &oldtup->t_self, newtup);

    InvokeObjectPostAlterHook(classId, objectId, 0);

    /* Release memory */
    pfree(values);
    pfree(nulls);
    pfree(replaces);
    heap_freetuple(newtup);

    ReleaseSysCache(oldtup);
}

/*
 * Executes an ALTER OBJECT / RENAME TO statement.  Based on the object
 * type, the function appropriate to that type is executed.
 *
 * Return value is the address of the renamed object.
 */
ObjectAddress
ExecRenameStmt(RenameStmt *stmt)
{
    switch (stmt->renameType)
    {
        case OBJECT_TABCONSTRAINT:
        case OBJECT_DOMCONSTRAINT:
            return RenameConstraint(stmt);

        case OBJECT_DATABASE:
            return RenameDatabase(stmt->subname, stmt->newname);

        case OBJECT_ROLE:
            return RenameRole(stmt->subname, stmt->newname);

        case OBJECT_SCHEMA:
            return RenameSchema(stmt->subname, stmt->newname);

        case OBJECT_TABLESPACE:
            return RenameTableSpace(stmt->subname, stmt->newname);

        case OBJECT_TABLE:
        case OBJECT_SEQUENCE:
        case OBJECT_VIEW:
        case OBJECT_MATVIEW:
        case OBJECT_INDEX:
        case OBJECT_FOREIGN_TABLE:
            return RenameRelation(stmt);

        case OBJECT_COLUMN:
        case OBJECT_ATTRIBUTE:
            return renameatt(stmt);

        case OBJECT_RULE:
            return RenameRewriteRule(stmt->relation, stmt->subname,
                                     stmt->newname);

        case OBJECT_TRIGGER:
            return renametrig(stmt);

        case OBJECT_POLICY:
            return rename_policy(stmt);

        case OBJECT_DOMAIN:
        case OBJECT_TYPE:
            return RenameType(stmt);

        case OBJECT_AGGREGATE:
        case OBJECT_COLLATION:
        case OBJECT_CONVERSION:
        case OBJECT_EVENT_TRIGGER:
        case OBJECT_FDW:
        case OBJECT_FOREIGN_SERVER:
        case OBJECT_FUNCTION:
        case OBJECT_OPCLASS:
        case OBJECT_OPFAMILY:
        case OBJECT_LANGUAGE:
        case OBJECT_PROCEDURE:
        case OBJECT_ROUTINE:
        case OBJECT_STATISTIC_EXT:
        case OBJECT_TSCONFIGURATION:
        case OBJECT_TSDICTIONARY:
        case OBJECT_TSPARSER:
        case OBJECT_TSTEMPLATE:
        case OBJECT_PUBLICATION:
        case OBJECT_SUBSCRIPTION:
            {
                ObjectAddress address;
                Relation    catalog;
                Relation    relation;

                address = get_object_address(stmt->renameType,
                                             stmt->object,
                                             &relation,
                                             AccessExclusiveLock, false);
                Assert(relation == NULL);

                catalog = table_open(address.classId, RowExclusiveLock);
                AlterObjectRename_internal(catalog,
                                           address.objectId,
                                           stmt->newname);
                table_close(catalog, RowExclusiveLock);

                return address;
            }

        default:
            elog(ERROR, "unrecognized rename stmt type: %d",
                 (int) stmt->renameType);
            return InvalidObjectAddress;    /* keep compiler happy */
    }
}

/*
 * Executes an ALTER OBJECT / DEPENDS ON [EXTENSION] statement.
 *
 * Return value is the address of the altered object.  refAddress is an output
 * argument which, if not null, receives the address of the object that the
 * altered object now depends on.
 */
ObjectAddress
ExecAlterObjectDependsStmt(AlterObjectDependsStmt *stmt, ObjectAddress *refAddress)
{
    ObjectAddress address;
    ObjectAddress refAddr;
    Relation    rel;

    address =
        get_object_address_rv(stmt->objectType, stmt->relation, (List *) stmt->object,
                              &rel, AccessExclusiveLock, false);

    /*
     * If a relation was involved, it would have been opened and locked. We
     * don't need the relation here, but we'll retain the lock until commit.
     */
    if (rel)
        table_close(rel, NoLock);

    refAddr = get_object_address(OBJECT_EXTENSION, (Node *) stmt->extname,
                                 &rel, AccessExclusiveLock, false);
    Assert(rel == NULL);
    if (refAddress)
        *refAddress = refAddr;

    recordDependencyOn(&address, &refAddr, DEPENDENCY_AUTO_EXTENSION);

    return address;
}

/*
 * Executes an ALTER OBJECT / SET SCHEMA statement.  Based on the object
 * type, the function appropriate to that type is executed.
 *
 * Return value is that of the altered object.
 *
 * oldSchemaAddr is an output argument which, if not NULL, is set to the object
 * address of the original schema.
 */
ObjectAddress
ExecAlterObjectSchemaStmt(AlterObjectSchemaStmt *stmt,
                          ObjectAddress *oldSchemaAddr)
{
    ObjectAddress address;
    Oid         oldNspOid;

    switch (stmt->objectType)
    {
        case OBJECT_EXTENSION:
            address = AlterExtensionNamespace(strVal((Value *) stmt->object), stmt->newschema,
                                              oldSchemaAddr ? &oldNspOid : NULL);
            break;

        case OBJECT_FOREIGN_TABLE:
        case OBJECT_SEQUENCE:
        case OBJECT_TABLE:
        case OBJECT_VIEW:
        case OBJECT_MATVIEW:
            address = AlterTableNamespace(stmt,
                                          oldSchemaAddr ? &oldNspOid : NULL);
            break;

        case OBJECT_DOMAIN:
        case OBJECT_TYPE:
            address = AlterTypeNamespace(castNode(List, stmt->object), stmt->newschema,
                                         stmt->objectType,
                                         oldSchemaAddr ? &oldNspOid : NULL);
            break;

            /* generic code path */
        case OBJECT_AGGREGATE:
        case OBJECT_COLLATION:
        case OBJECT_CONVERSION:
        case OBJECT_FUNCTION:
        case OBJECT_OPERATOR:
        case OBJECT_OPCLASS:
        case OBJECT_OPFAMILY:
        case OBJECT_PROCEDURE:
        case OBJECT_ROUTINE:
        case OBJECT_STATISTIC_EXT:
        case OBJECT_TSCONFIGURATION:
        case OBJECT_TSDICTIONARY:
        case OBJECT_TSPARSER:
        case OBJECT_TSTEMPLATE:
            {
                Relation    catalog;
                Relation    relation;
                Oid         classId;
                Oid         nspOid;

                address = get_object_address(stmt->objectType,
                                             stmt->object,
                                             &relation,
                                             AccessExclusiveLock,
                                             false);
                Assert(relation == NULL);
                classId = address.classId;
                catalog = table_open(classId, RowExclusiveLock);
                nspOid = LookupCreationNamespace(stmt->newschema);

                oldNspOid = AlterObjectNamespace_internal(catalog, address.objectId,
                                                          nspOid);
                table_close(catalog, RowExclusiveLock);
            }
            break;

        default:
            elog(ERROR, "unrecognized AlterObjectSchemaStmt type: %d",
                 (int) stmt->objectType);
            return InvalidObjectAddress;    /* keep compiler happy */
    }

    if (oldSchemaAddr)
        ObjectAddressSet(*oldSchemaAddr, NamespaceRelationId, oldNspOid);

    return address;
}

/*
 * Change an object's namespace given its classOid and object Oid.
 *
 * Objects that don't have a namespace should be ignored.
 *
 * This function is currently used only by ALTER EXTENSION SET SCHEMA,
 * so it only needs to cover object types that can be members of an
 * extension, and it doesn't have to deal with certain special cases
 * such as not wanting to process array types --- those should never
 * be direct members of an extension anyway.  Nonetheless, we insist
 * on listing all OCLASS types in the switch.
 *
 * Returns the OID of the object's previous namespace, or InvalidOid if
 * object doesn't have a schema.
 */
Oid
AlterObjectNamespace_oid(Oid classId, Oid objid, Oid nspOid,
                         ObjectAddresses *objsMoved)
{
    Oid         oldNspOid = InvalidOid;
    ObjectAddress dep;

    dep.classId = classId;
    dep.objectId = objid;
    dep.objectSubId = 0;

    switch (getObjectClass(&dep))
    {
        case OCLASS_CLASS:
            {
                Relation    rel;

                rel = relation_open(objid, AccessExclusiveLock);
                oldNspOid = RelationGetNamespace(rel);

                AlterTableNamespaceInternal(rel, oldNspOid, nspOid, objsMoved);

                relation_close(rel, NoLock);
                break;
            }

        case OCLASS_TYPE:
            oldNspOid = AlterTypeNamespace_oid(objid, nspOid, objsMoved);
            break;

        case OCLASS_PROC:
        case OCLASS_COLLATION:
        case OCLASS_CONVERSION:
        case OCLASS_OPERATOR:
        case OCLASS_OPCLASS:
        case OCLASS_OPFAMILY:
        case OCLASS_STATISTIC_EXT:
        case OCLASS_TSPARSER:
        case OCLASS_TSDICT:
        case OCLASS_TSTEMPLATE:
        case OCLASS_TSCONFIG:
            {
                Relation    catalog;

                catalog = table_open(classId, RowExclusiveLock);

                oldNspOid = AlterObjectNamespace_internal(catalog, objid,
                                                          nspOid);

                table_close(catalog, RowExclusiveLock);
            }
            break;

        case OCLASS_CAST:
        case OCLASS_CONSTRAINT:
        case OCLASS_DEFAULT:
        case OCLASS_LANGUAGE:
        case OCLASS_LARGEOBJECT:
        case OCLASS_AM:
        case OCLASS_AMOP:
        case OCLASS_AMPROC:
        case OCLASS_REWRITE:
        case OCLASS_TRIGGER:
        case OCLASS_SCHEMA:
        case OCLASS_ROLE:
        case OCLASS_DATABASE:
        case OCLASS_TBLSPACE:
        case OCLASS_FDW:
        case OCLASS_FOREIGN_SERVER:
        case OCLASS_USER_MAPPING:
        case OCLASS_DEFACL:
        case OCLASS_EXTENSION:
        case OCLASS_EVENT_TRIGGER:
        case OCLASS_POLICY:
        case OCLASS_PUBLICATION:
        case OCLASS_PUBLICATION_REL:
        case OCLASS_SUBSCRIPTION:
        case OCLASS_TRANSFORM:
            /* ignore object types that don't have schema-qualified names */
            break;

            /*
             * There's intentionally no default: case here; we want the
             * compiler to warn if a new OCLASS hasn't been handled above.
             */
    }

    return oldNspOid;
}

/*
 * Generic function to change the namespace of a given object, for simple
 * cases (won't work for tables, nor other cases where we need to do more
 * than change the namespace column of a single catalog entry).
 *
 * rel: catalog relation containing object (RowExclusiveLock'd by caller)
 * objid: OID of object to change the namespace of
 * nspOid: OID of new namespace
 *
 * Returns the OID of the object's previous namespace.
 */
static Oid
AlterObjectNamespace_internal(Relation rel, Oid objid, Oid nspOid)
{
    Oid         classId = RelationGetRelid(rel);
    int         oidCacheId = get_object_catcache_oid(classId);
    int         nameCacheId = get_object_catcache_name(classId);
    AttrNumber  Anum_name = get_object_attnum_name(classId);
    AttrNumber  Anum_namespace = get_object_attnum_namespace(classId);
    AttrNumber  Anum_owner = get_object_attnum_owner(classId);
    Oid         oldNspOid;
    Datum       name,
                namespace;
    bool        isnull;
    HeapTuple   tup,
                newtup;
    Datum      *values;
    bool       *nulls;
    bool       *replaces;

    tup = SearchSysCacheCopy1(oidCacheId, ObjectIdGetDatum(objid));
    if (!HeapTupleIsValid(tup)) /* should not happen */
        elog(ERROR, "cache lookup failed for object %u of catalog \"%s\"",
             objid, RelationGetRelationName(rel));

    name = heap_getattr(tup, Anum_name, RelationGetDescr(rel), &isnull);
    Assert(!isnull);
    namespace = heap_getattr(tup, Anum_namespace, RelationGetDescr(rel),
                             &isnull);
    Assert(!isnull);
    oldNspOid = DatumGetObjectId(namespace);

    /*
     * If the object is already in the correct namespace, we don't need to do
     * anything except fire the object access hook.
     */
    if (oldNspOid == nspOid)
    {
        InvokeObjectPostAlterHook(classId, objid, 0);
        return oldNspOid;
    }

    /* Check basic namespace related issues */
    CheckSetNamespace(oldNspOid, nspOid);

    /* Permission checks ... superusers can always do it */
    if (!superuser())
    {
        Datum       owner;
        Oid         ownerId;
        AclResult   aclresult;

        /* Fail if object does not have an explicit owner */
        if (Anum_owner <= 0)
            ereport(ERROR,
                    (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                     (errmsg("must be superuser to set schema of %s",
                             getObjectDescriptionOids(classId, objid)))));

        /* Otherwise, must be owner of the existing object */
        owner = heap_getattr(tup, Anum_owner, RelationGetDescr(rel), &isnull);
        Assert(!isnull);
        ownerId = DatumGetObjectId(owner);

        if (!has_privs_of_role(GetUserId(), ownerId))
            aclcheck_error(ACLCHECK_NOT_OWNER, get_object_type(classId, objid),
                           NameStr(*(DatumGetName(name))));

        /* User must have CREATE privilege on new namespace */
        aclresult = pg_namespace_aclcheck(nspOid, GetUserId(), ACL_CREATE);
        if (aclresult != ACLCHECK_OK)
            aclcheck_error(aclresult, OBJECT_SCHEMA,
                           get_namespace_name(nspOid));
    }

    /*
     * Check for duplicate name (more friendly than unique-index failure).
     * Since this is just a friendliness check, we can just skip it in cases
     * where there isn't suitable support.
     */
    if (classId == ProcedureRelationId)
    {
        Form_pg_proc proc = (Form_pg_proc) GETSTRUCT(tup);

        IsThereFunctionInNamespace(NameStr(proc->proname), proc->pronargs,
                                   &proc->proargtypes, nspOid);
    }
    else if (classId == CollationRelationId)
    {
        Form_pg_collation coll = (Form_pg_collation) GETSTRUCT(tup);

        IsThereCollationInNamespace(NameStr(coll->collname), nspOid);
    }
    else if (classId == OperatorClassRelationId)
    {
        Form_pg_opclass opc = (Form_pg_opclass) GETSTRUCT(tup);

        IsThereOpClassInNamespace(NameStr(opc->opcname),
                                  opc->opcmethod, nspOid);
    }
    else if (classId == OperatorFamilyRelationId)
    {
        Form_pg_opfamily opf = (Form_pg_opfamily) GETSTRUCT(tup);

        IsThereOpFamilyInNamespace(NameStr(opf->opfname),
                                   opf->opfmethod, nspOid);
    }
    else if (nameCacheId >= 0 &&
             SearchSysCacheExists2(nameCacheId, name,
                                   ObjectIdGetDatum(nspOid)))
        report_namespace_conflict(classId,
                                  NameStr(*(DatumGetName(name))),
                                  nspOid);

    /* Build modified tuple */
    values = palloc0(RelationGetNumberOfAttributes(rel) * sizeof(Datum));
    nulls = palloc0(RelationGetNumberOfAttributes(rel) * sizeof(bool));
    replaces = palloc0(RelationGetNumberOfAttributes(rel) * sizeof(bool));
    values[Anum_namespace - 1] = ObjectIdGetDatum(nspOid);
    replaces[Anum_namespace - 1] = true;
    newtup = heap_modify_tuple(tup, RelationGetDescr(rel),
                               values, nulls, replaces);

    /* Perform actual update */
    CatalogTupleUpdate(rel, &tup->t_self, newtup);

    /* Release memory */
    pfree(values);
    pfree(nulls);
    pfree(replaces);

    /* update dependencies to point to the new schema */
    changeDependencyFor(classId, objid,
                        NamespaceRelationId, oldNspOid, nspOid);

    InvokeObjectPostAlterHook(classId, objid, 0);

    return oldNspOid;
}

/*
 * Executes an ALTER OBJECT / OWNER TO statement.  Based on the object
 * type, the function appropriate to that type is executed.
 */
ObjectAddress
ExecAlterOwnerStmt(AlterOwnerStmt *stmt)
{
    Oid         newowner = get_rolespec_oid(stmt->newowner, false);

    switch (stmt->objectType)
    {
        case OBJECT_DATABASE:
            return AlterDatabaseOwner(strVal((Value *) stmt->object), newowner);

        case OBJECT_SCHEMA:
            return AlterSchemaOwner(strVal((Value *) stmt->object), newowner);

        case OBJECT_TYPE:
        case OBJECT_DOMAIN:     /* same as TYPE */
            return AlterTypeOwner(castNode(List, stmt->object), newowner, stmt->objectType);
            break;

        case OBJECT_FDW:
            return AlterForeignDataWrapperOwner(strVal((Value *) stmt->object),
                                                newowner);

        case OBJECT_FOREIGN_SERVER:
            return AlterForeignServerOwner(strVal((Value *) stmt->object),
                                           newowner);

        case OBJECT_EVENT_TRIGGER:
            return AlterEventTriggerOwner(strVal((Value *) stmt->object),
                                          newowner);

        case OBJECT_PUBLICATION:
            return AlterPublicationOwner(strVal((Value *) stmt->object),
                                         newowner);

        case OBJECT_SUBSCRIPTION:
            return AlterSubscriptionOwner(strVal((Value *) stmt->object),
                                          newowner);

            /* Generic cases */
        case OBJECT_AGGREGATE:
        case OBJECT_COLLATION:
        case OBJECT_CONVERSION:
        case OBJECT_FUNCTION:
        case OBJECT_LANGUAGE:
        case OBJECT_LARGEOBJECT:
        case OBJECT_OPERATOR:
        case OBJECT_OPCLASS:
        case OBJECT_OPFAMILY:
        case OBJECT_PROCEDURE:
        case OBJECT_ROUTINE:
        case OBJECT_STATISTIC_EXT:
        case OBJECT_TABLESPACE:
        case OBJECT_TSDICTIONARY:
        case OBJECT_TSCONFIGURATION:
            {
                Relation    catalog;
                Relation    relation;
                Oid         classId;
                ObjectAddress address;

                address = get_object_address(stmt->objectType,
                                             stmt->object,
                                             &relation,
                                             AccessExclusiveLock,
                                             false);
                Assert(relation == NULL);
                classId = address.classId;

                /*
                 * XXX - get_object_address returns Oid of pg_largeobject
                 * catalog for OBJECT_LARGEOBJECT because of historical
                 * reasons.  Fix up it here.
                 */
                if (classId == LargeObjectRelationId)
                    classId = LargeObjectMetadataRelationId;

                catalog = table_open(classId, RowExclusiveLock);

                AlterObjectOwner_internal(catalog, address.objectId, newowner);
                table_close(catalog, RowExclusiveLock);

                return address;
            }
            break;

        default:
            elog(ERROR, "unrecognized AlterOwnerStmt type: %d",
                 (int) stmt->objectType);
            return InvalidObjectAddress;    /* keep compiler happy */
    }
}

/*
 * Generic function to change the ownership of a given object, for simple
 * cases (won't work for tables, nor other cases where we need to do more than
 * change the ownership column of a single catalog entry).
 *
 * rel: catalog relation containing object (RowExclusiveLock'd by caller)
 * objectId: OID of object to change the ownership of
 * new_ownerId: OID of new object owner
 */
void
AlterObjectOwner_internal(Relation rel, Oid objectId, Oid new_ownerId)
{
    Oid         classId = RelationGetRelid(rel);
    AttrNumber  Anum_oid = get_object_attnum_oid(classId);
    AttrNumber  Anum_owner = get_object_attnum_owner(classId);
    AttrNumber  Anum_namespace = get_object_attnum_namespace(classId);
    AttrNumber  Anum_acl = get_object_attnum_acl(classId);
    AttrNumber  Anum_name = get_object_attnum_name(classId);
    HeapTuple   oldtup;
    Datum       datum;
    bool        isnull;
    Oid         old_ownerId;
    Oid         namespaceId = InvalidOid;

    oldtup = get_catalog_object_by_oid(rel, Anum_oid, objectId);
    if (oldtup == NULL)
        elog(ERROR, "cache lookup failed for object %u of catalog \"%s\"",
             objectId, RelationGetRelationName(rel));

    datum = heap_getattr(oldtup, Anum_owner,
                         RelationGetDescr(rel), &isnull);
    Assert(!isnull);
    old_ownerId = DatumGetObjectId(datum);

    if (Anum_namespace != InvalidAttrNumber)
    {
        datum = heap_getattr(oldtup, Anum_namespace,
                             RelationGetDescr(rel), &isnull);
        Assert(!isnull);
        namespaceId = DatumGetObjectId(datum);
    }

    if (old_ownerId != new_ownerId)
    {
        AttrNumber  nattrs;
        HeapTuple   newtup;
        Datum      *values;
        bool       *nulls;
        bool       *replaces;

        /* Superusers can bypass permission checks */
        if (!superuser())
        {
            /* must be owner */
            if (!has_privs_of_role(GetUserId(), old_ownerId))
            {
                char       *objname;
                char        namebuf[NAMEDATALEN];

                if (Anum_name != InvalidAttrNumber)
                {
                    datum = heap_getattr(oldtup, Anum_name,
                                         RelationGetDescr(rel), &isnull);
                    Assert(!isnull);
                    objname = NameStr(*DatumGetName(datum));
                }
                else
                {
                    snprintf(namebuf, sizeof(namebuf), "%u", objectId);
                    objname = namebuf;
                }
                aclcheck_error(ACLCHECK_NOT_OWNER, get_object_type(classId, objectId),
                               objname);
            }
            /* Must be able to become new owner */
            check_is_member_of_role(GetUserId(), new_ownerId);

            /* New owner must have CREATE privilege on namespace */
            if (OidIsValid(namespaceId))
            {
                AclResult   aclresult;

                aclresult = pg_namespace_aclcheck(namespaceId, new_ownerId,
                                                  ACL_CREATE);
                if (aclresult != ACLCHECK_OK)
                    aclcheck_error(aclresult, OBJECT_SCHEMA,
                                   get_namespace_name(namespaceId));
            }
        }

        /* Build a modified tuple */
        nattrs = RelationGetNumberOfAttributes(rel);
        values = palloc0(nattrs * sizeof(Datum));
        nulls = palloc0(nattrs * sizeof(bool));
        replaces = palloc0(nattrs * sizeof(bool));
        values[Anum_owner - 1] = ObjectIdGetDatum(new_ownerId);
        replaces[Anum_owner - 1] = true;

        /*
         * Determine the modified ACL for the new owner.  This is only
         * necessary when the ACL is non-null.
         */
        if (Anum_acl != InvalidAttrNumber)
        {
            datum = heap_getattr(oldtup,
                                 Anum_acl, RelationGetDescr(rel), &isnull);
            if (!isnull)
            {
                Acl        *newAcl;

                newAcl = aclnewowner(DatumGetAclP(datum),
                                     old_ownerId, new_ownerId);
                values[Anum_acl - 1] = PointerGetDatum(newAcl);
                replaces[Anum_acl - 1] = true;
            }
        }

        newtup = heap_modify_tuple(oldtup, RelationGetDescr(rel),
                                   values, nulls, replaces);

        /* Perform actual update */
        CatalogTupleUpdate(rel, &newtup->t_self, newtup);

        /* Update owner dependency reference */
        if (classId == LargeObjectMetadataRelationId)
            classId = LargeObjectRelationId;
        changeDependencyOnOwner(classId, objectId, new_ownerId);

        /* Release memory */
        pfree(values);
        pfree(nulls);
        pfree(replaces);
    }

    InvokeObjectPostAlterHook(classId, objectId, 0);
}