pg_operator.c

Go to the documentation of this file.

/*-------------------------------------------------------------------------
 *
 * pg_operator.c
 *    routines to support manipulation of the pg_operator relation
 *
 * Portions Copyright (c) 1996-2018, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *    src/backend/catalog/pg_operator.c
 *
 * NOTES
 *    these routines moved here from commands/define.c and somewhat cleaned up.
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include "access/heapam.h"
#include "access/htup_details.h"
#include "access/xact.h"
#include "catalog/dependency.h"
#include "catalog/indexing.h"
#include "catalog/namespace.h"
#include "catalog/objectaccess.h"
#include "catalog/pg_namespace.h"
#include "catalog/pg_operator.h"
#include "catalog/pg_proc.h"
#include "catalog/pg_type.h"
#include "miscadmin.h"
#include "parser/parse_oper.h"
#include "utils/acl.h"
#include "utils/builtins.h"
#include "utils/lsyscache.h"
#include "utils/rel.h"
#include "utils/syscache.h"


static Oid OperatorGet(const char *operatorName,
            Oid operatorNamespace,
            Oid leftObjectId,
            Oid rightObjectId,
            bool *defined);

static Oid OperatorLookup(List *operatorName,
               Oid leftObjectId,
               Oid rightObjectId,
               bool *defined);

static Oid OperatorShellMake(const char *operatorName,
                  Oid operatorNamespace,
                  Oid leftTypeId,
                  Oid rightTypeId);

static Oid get_other_operator(List *otherOp,
                   Oid otherLeftTypeId, Oid otherRightTypeId,
                   const char *operatorName, Oid operatorNamespace,
                   Oid leftTypeId, Oid rightTypeId,
                   bool isCommutator);


/*
 * Check whether a proposed operator name is legal
 *
 * This had better match the behavior of parser/scan.l!
 *
 * We need this because the parser is not smart enough to check that
 * the arguments of CREATE OPERATOR's COMMUTATOR, NEGATOR, etc clauses
 * are operator names rather than some other lexical entity.
 */
static bool
validOperatorName(const char *name)
{
    size_t      len = strlen(name);

    /* Can't be empty or too long */
    if (len == 0 || len >= NAMEDATALEN)
        return false;

    /* Can't contain any invalid characters */
    /* Test string here should match op_chars in scan.l */
    if (strspn(name, "~!@#^&|`?+-*/%<>=") != len)
        return false;

    /* Can't contain slash-star or dash-dash (comment starts) */
    if (strstr(name, "/*") || strstr(name, "--"))
        return false;

    /*
     * For SQL standard compatibility, '+' and '-' cannot be the last char of
     * a multi-char operator unless the operator contains chars that are not
     * in SQL operators. The idea is to lex '=-' as two operators, but not to
     * forbid operator names like '?-' that could not be sequences of standard
     * SQL operators.
     */
    if (len > 1 &&
        (name[len - 1] == '+' ||
         name[len - 1] == '-'))
    {
        int         ic;

        for (ic = len - 2; ic >= 0; ic--)
        {
            if (strchr("~!@#^&|`?%", name[ic]))
                break;
        }
        if (ic < 0)
            return false;       /* nope, not valid */
    }

    /* != isn't valid either, because parser will convert it to <> */
    if (strcmp(name, "!=") == 0)
        return false;

    return true;
}


/*
 * OperatorGet
 *
 *      finds an operator given an exact specification (name, namespace,
 *      left and right type IDs).
 *
 *      *defined is set true if defined (not a shell)
 */
static Oid
OperatorGet(const char *operatorName,
            Oid operatorNamespace,
            Oid leftObjectId,
            Oid rightObjectId,
            bool *defined)
{
    HeapTuple   tup;
    Oid         operatorObjectId;

    tup = SearchSysCache4(OPERNAMENSP,
                          PointerGetDatum(operatorName),
                          ObjectIdGetDatum(leftObjectId),
                          ObjectIdGetDatum(rightObjectId),
                          ObjectIdGetDatum(operatorNamespace));
    if (HeapTupleIsValid(tup))
    {
        RegProcedure oprcode = ((Form_pg_operator) GETSTRUCT(tup))->oprcode;

        operatorObjectId = HeapTupleGetOid(tup);
        *defined = RegProcedureIsValid(oprcode);
        ReleaseSysCache(tup);
    }
    else
    {
        operatorObjectId = InvalidOid;
        *defined = false;
    }

    return operatorObjectId;
}

/*
 * OperatorLookup
 *
 *      looks up an operator given a possibly-qualified name and
 *      left and right type IDs.
 *
 *      *defined is set true if defined (not a shell)
 */
static Oid
OperatorLookup(List *operatorName,
               Oid leftObjectId,
               Oid rightObjectId,
               bool *defined)
{
    Oid         operatorObjectId;
    RegProcedure oprcode;

    operatorObjectId = LookupOperName(NULL, operatorName,
                                      leftObjectId, rightObjectId,
                                      true, -1);
    if (!OidIsValid(operatorObjectId))
    {
        *defined = false;
        return InvalidOid;
    }

    oprcode = get_opcode(operatorObjectId);
    *defined = RegProcedureIsValid(oprcode);

    return operatorObjectId;
}


/*
 * OperatorShellMake
 *      Make a "shell" entry for a not-yet-existing operator.
 */
static Oid
OperatorShellMake(const char *operatorName,
                  Oid operatorNamespace,
                  Oid leftTypeId,
                  Oid rightTypeId)
{
    Relation    pg_operator_desc;
    Oid         operatorObjectId;
    int         i;
    HeapTuple   tup;
    Datum       values[Natts_pg_operator];
    bool        nulls[Natts_pg_operator];
    NameData    oname;
    TupleDesc   tupDesc;

    /*
     * validate operator name
     */
    if (!validOperatorName(operatorName))
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_NAME),
                 errmsg("\"%s\" is not a valid operator name",
                        operatorName)));

    /*
     * initialize our *nulls and *values arrays
     */
    for (i = 0; i < Natts_pg_operator; ++i)
    {
        nulls[i] = false;
        values[i] = (Datum) NULL;   /* redundant, but safe */
    }

    /*
     * initialize values[] with the operator name and input data types. Note
     * that oprcode is set to InvalidOid, indicating it's a shell.
     */
    namestrcpy(&oname, operatorName);
    values[Anum_pg_operator_oprname - 1] = NameGetDatum(&oname);
    values[Anum_pg_operator_oprnamespace - 1] = ObjectIdGetDatum(operatorNamespace);
    values[Anum_pg_operator_oprowner - 1] = ObjectIdGetDatum(GetUserId());
    values[Anum_pg_operator_oprkind - 1] = CharGetDatum(leftTypeId ? (rightTypeId ? 'b' : 'r') : 'l');
    values[Anum_pg_operator_oprcanmerge - 1] = BoolGetDatum(false);
    values[Anum_pg_operator_oprcanhash - 1] = BoolGetDatum(false);
    values[Anum_pg_operator_oprleft - 1] = ObjectIdGetDatum(leftTypeId);
    values[Anum_pg_operator_oprright - 1] = ObjectIdGetDatum(rightTypeId);
    values[Anum_pg_operator_oprresult - 1] = ObjectIdGetDatum(InvalidOid);
    values[Anum_pg_operator_oprcom - 1] = ObjectIdGetDatum(InvalidOid);
    values[Anum_pg_operator_oprnegate - 1] = ObjectIdGetDatum(InvalidOid);
    values[Anum_pg_operator_oprcode - 1] = ObjectIdGetDatum(InvalidOid);
    values[Anum_pg_operator_oprrest - 1] = ObjectIdGetDatum(InvalidOid);
    values[Anum_pg_operator_oprjoin - 1] = ObjectIdGetDatum(InvalidOid);

    /*
     * open pg_operator
     */
    pg_operator_desc = heap_open(OperatorRelationId, RowExclusiveLock);
    tupDesc = pg_operator_desc->rd_att;

    /*
     * create a new operator tuple
     */
    tup = heap_form_tuple(tupDesc, values, nulls);

    /*
     * insert our "shell" operator tuple
     */
    operatorObjectId = CatalogTupleInsert(pg_operator_desc, tup);

    /* Add dependencies for the entry */
    makeOperatorDependencies(tup, false);

    heap_freetuple(tup);

    /* Post creation hook for new shell operator */
    InvokeObjectPostCreateHook(OperatorRelationId, operatorObjectId, 0);

    /*
     * Make sure the tuple is visible for subsequent lookups/updates.
     */
    CommandCounterIncrement();

    /*
     * close the operator relation and return the oid.
     */
    heap_close(pg_operator_desc, RowExclusiveLock);

    return operatorObjectId;
}

/*
 * OperatorCreate
 *
 * "X" indicates an optional argument (i.e. one that can be NULL or 0)
 *      operatorName            name for new operator
 *      operatorNamespace       namespace for new operator
 *      leftTypeId              X left type ID
 *      rightTypeId             X right type ID
 *      procedureId             procedure ID for operator
 *      commutatorName          X commutator operator
 *      negatorName             X negator operator
 *      restrictionId           X restriction selectivity procedure ID
 *      joinId                  X join selectivity procedure ID
 *      canMerge                merge join can be used with this operator
 *      canHash                 hash join can be used with this operator
 *
 * The caller should have validated properties and permissions for the
 * objects passed as OID references.  We must handle the commutator and
 * negator operator references specially, however, since those need not
 * exist beforehand.
 *
 * This routine gets complicated because it allows the user to
 * specify operators that do not exist.  For example, if operator
 * "op" is being defined, the negator operator "negop" and the
 * commutator "commop" can also be defined without specifying
 * any information other than their names.  Since in order to
 * add "op" to the PG_OPERATOR catalog, all the Oid's for these
 * operators must be placed in the fields of "op", a forward
 * declaration is done on the commutator and negator operators.
 * This is called creating a shell, and its main effect is to
 * create a tuple in the PG_OPERATOR catalog with minimal
 * information about the operator (just its name and types).
 * Forward declaration is used only for this purpose, it is
 * not available to the user as it is for type definition.
 */
ObjectAddress
OperatorCreate(const char *operatorName,
               Oid operatorNamespace,
               Oid leftTypeId,
               Oid rightTypeId,
               Oid procedureId,
               List *commutatorName,
               List *negatorName,
               Oid restrictionId,
               Oid joinId,
               bool canMerge,
               bool canHash)
{
    Relation    pg_operator_desc;
    HeapTuple   tup;
    bool        isUpdate;
    bool        nulls[Natts_pg_operator];
    bool        replaces[Natts_pg_operator];
    Datum       values[Natts_pg_operator];
    Oid         operatorObjectId;
    bool        operatorAlreadyDefined;
    Oid         operResultType;
    Oid         commutatorId,
                negatorId;
    bool        selfCommutator = false;
    NameData    oname;
    int         i;
    ObjectAddress address;

    /*
     * Sanity checks
     */
    if (!validOperatorName(operatorName))
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_NAME),
                 errmsg("\"%s\" is not a valid operator name",
                        operatorName)));

    if (!(OidIsValid(leftTypeId) && OidIsValid(rightTypeId)))
    {
        /* If it's not a binary op, these things mustn't be set: */
        if (commutatorName)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
                     errmsg("only binary operators can have commutators")));
        if (OidIsValid(joinId))
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
                     errmsg("only binary operators can have join selectivity")));
        if (canMerge)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
                     errmsg("only binary operators can merge join")));
        if (canHash)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
                     errmsg("only binary operators can hash")));
    }

    operResultType = get_func_rettype(procedureId);

    if (operResultType != BOOLOID)
    {
        /* If it's not a boolean op, these things mustn't be set: */
        if (negatorName)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
                     errmsg("only boolean operators can have negators")));
        if (OidIsValid(restrictionId))
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
                     errmsg("only boolean operators can have restriction selectivity")));
        if (OidIsValid(joinId))
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
                     errmsg("only boolean operators can have join selectivity")));
        if (canMerge)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
                     errmsg("only boolean operators can merge join")));
        if (canHash)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
                     errmsg("only boolean operators can hash")));
    }

    operatorObjectId = OperatorGet(operatorName,
                                   operatorNamespace,
                                   leftTypeId,
                                   rightTypeId,
                                   &operatorAlreadyDefined);

    if (operatorAlreadyDefined)
        ereport(ERROR,
                (errcode(ERRCODE_DUPLICATE_FUNCTION),
                 errmsg("operator %s already exists",
                        operatorName)));

    /*
     * At this point, if operatorObjectId is not InvalidOid then we are
     * filling in a previously-created shell.  Insist that the user own any
     * such shell.
     */
    if (OidIsValid(operatorObjectId) &&
        !pg_oper_ownercheck(operatorObjectId, GetUserId()))
        aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_OPERATOR,
                       operatorName);

    /*
     * Set up the other operators.  If they do not currently exist, create
     * shells in order to get ObjectId's.
     */

    if (commutatorName)
    {
        /* commutator has reversed arg types */
        commutatorId = get_other_operator(commutatorName,
                                          rightTypeId, leftTypeId,
                                          operatorName, operatorNamespace,
                                          leftTypeId, rightTypeId,
                                          true);

        /* Permission check: must own other operator */
        if (OidIsValid(commutatorId) &&
            !pg_oper_ownercheck(commutatorId, GetUserId()))
            aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_OPERATOR,
                           NameListToString(commutatorName));

        /*
         * self-linkage to this operator; will fix below. Note that only
         * self-linkage for commutation makes sense.
         */
        if (!OidIsValid(commutatorId))
            selfCommutator = true;
    }
    else
        commutatorId = InvalidOid;

    if (negatorName)
    {
        /* negator has same arg types */
        negatorId = get_other_operator(negatorName,
                                       leftTypeId, rightTypeId,
                                       operatorName, operatorNamespace,
                                       leftTypeId, rightTypeId,
                                       false);

        /* Permission check: must own other operator */
        if (OidIsValid(negatorId) &&
            !pg_oper_ownercheck(negatorId, GetUserId()))
            aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_OPERATOR,
                           NameListToString(negatorName));
    }
    else
        negatorId = InvalidOid;

    /*
     * set up values in the operator tuple
     */

    for (i = 0; i < Natts_pg_operator; ++i)
    {
        values[i] = (Datum) NULL;
        replaces[i] = true;
        nulls[i] = false;
    }

    namestrcpy(&oname, operatorName);
    values[Anum_pg_operator_oprname - 1] = NameGetDatum(&oname);
    values[Anum_pg_operator_oprnamespace - 1] = ObjectIdGetDatum(operatorNamespace);
    values[Anum_pg_operator_oprowner - 1] = ObjectIdGetDatum(GetUserId());
    values[Anum_pg_operator_oprkind - 1] = CharGetDatum(leftTypeId ? (rightTypeId ? 'b' : 'r') : 'l');
    values[Anum_pg_operator_oprcanmerge - 1] = BoolGetDatum(canMerge);
    values[Anum_pg_operator_oprcanhash - 1] = BoolGetDatum(canHash);
    values[Anum_pg_operator_oprleft - 1] = ObjectIdGetDatum(leftTypeId);
    values[Anum_pg_operator_oprright - 1] = ObjectIdGetDatum(rightTypeId);
    values[Anum_pg_operator_oprresult - 1] = ObjectIdGetDatum(operResultType);
    values[Anum_pg_operator_oprcom - 1] = ObjectIdGetDatum(commutatorId);
    values[Anum_pg_operator_oprnegate - 1] = ObjectIdGetDatum(negatorId);
    values[Anum_pg_operator_oprcode - 1] = ObjectIdGetDatum(procedureId);
    values[Anum_pg_operator_oprrest - 1] = ObjectIdGetDatum(restrictionId);
    values[Anum_pg_operator_oprjoin - 1] = ObjectIdGetDatum(joinId);

    pg_operator_desc = heap_open(OperatorRelationId, RowExclusiveLock);

    /*
     * If we are replacing an operator shell, update; else insert
     */
    if (operatorObjectId)
    {
        isUpdate = true;

        tup = SearchSysCacheCopy1(OPEROID,
                                  ObjectIdGetDatum(operatorObjectId));
        if (!HeapTupleIsValid(tup))
            elog(ERROR, "cache lookup failed for operator %u",
                 operatorObjectId);

        tup = heap_modify_tuple(tup,
                                RelationGetDescr(pg_operator_desc),
                                values,
                                nulls,
                                replaces);

        CatalogTupleUpdate(pg_operator_desc, &tup->t_self, tup);
    }
    else
    {
        isUpdate = false;

        tup = heap_form_tuple(RelationGetDescr(pg_operator_desc),
                              values, nulls);

        operatorObjectId = CatalogTupleInsert(pg_operator_desc, tup);
    }

    /* Add dependencies for the entry */
    address = makeOperatorDependencies(tup, isUpdate);

    /* Post creation hook for new operator */
    InvokeObjectPostCreateHook(OperatorRelationId, operatorObjectId, 0);

    heap_close(pg_operator_desc, RowExclusiveLock);

    /*
     * If a commutator and/or negator link is provided, update the other
     * operator(s) to point at this one, if they don't already have a link.
     * This supports an alternative style of operator definition wherein the
     * user first defines one operator without giving negator or commutator,
     * then defines the other operator of the pair with the proper commutator
     * or negator attribute.  That style doesn't require creation of a shell,
     * and it's the only style that worked right before Postgres version 6.5.
     * This code also takes care of the situation where the new operator is
     * its own commutator.
     */
    if (selfCommutator)
        commutatorId = operatorObjectId;

    if (OidIsValid(commutatorId) || OidIsValid(negatorId))
        OperatorUpd(operatorObjectId, commutatorId, negatorId, false);

    return address;
}

/*
 * Try to lookup another operator (commutator, etc)
 *
 * If not found, check to see if it is exactly the operator we are trying
 * to define; if so, return InvalidOid.  (Note that this case is only
 * sensible for a commutator, so we error out otherwise.)  If it is not
 * the same operator, create a shell operator.
 */
static Oid
get_other_operator(List *otherOp, Oid otherLeftTypeId, Oid otherRightTypeId,
                   const char *operatorName, Oid operatorNamespace,
                   Oid leftTypeId, Oid rightTypeId, bool isCommutator)
{
    Oid         other_oid;
    bool        otherDefined;
    char       *otherName;
    Oid         otherNamespace;
    AclResult   aclresult;

    other_oid = OperatorLookup(otherOp,
                               otherLeftTypeId,
                               otherRightTypeId,
                               &otherDefined);

    if (OidIsValid(other_oid))
    {
        /* other op already in catalogs */
        return other_oid;
    }

    otherNamespace = QualifiedNameGetCreationNamespace(otherOp,
                                                       &otherName);

    if (strcmp(otherName, operatorName) == 0 &&
        otherNamespace == operatorNamespace &&
        otherLeftTypeId == leftTypeId &&
        otherRightTypeId == rightTypeId)
    {
        /*
         * self-linkage to this operator; caller will fix later. Note that
         * only self-linkage for commutation makes sense.
         */
        if (!isCommutator)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
                     errmsg("operator cannot be its own negator or sort operator")));
        return InvalidOid;
    }

    /* not in catalogs, different from operator, so make shell */

    aclresult = pg_namespace_aclcheck(otherNamespace, GetUserId(),
                                      ACL_CREATE);
    if (aclresult != ACLCHECK_OK)
        aclcheck_error(aclresult, OBJECT_SCHEMA,
                       get_namespace_name(otherNamespace));

    other_oid = OperatorShellMake(otherName,
                                  otherNamespace,
                                  otherLeftTypeId,
                                  otherRightTypeId);
    return other_oid;
}

/*
 * OperatorUpd
 *
 *  For a given operator, look up its negator and commutator operators.
 *  When isDelete is false, update their negator and commutator fields to
 *  point back to the given operator; when isDelete is true, update those
 *  fields to no longer point back to the given operator.
 *
 *  The !isDelete case solves a problem for users who need to insert two new
 *  operators that are the negator or commutator of each other, while the
 *  isDelete case is needed so as not to leave dangling OID links behind
 *  after dropping an operator.
 */
void
OperatorUpd(Oid baseId, Oid commId, Oid negId, bool isDelete)
{
    Relation    pg_operator_desc;
    HeapTuple   tup;

    /*
     * If we're making an operator into its own commutator, then we need a
     * command-counter increment here, since we've just inserted the tuple
     * we're about to update.  But when we're dropping an operator, we can
     * skip this because we're at the beginning of the command.
     */
    if (!isDelete)
        CommandCounterIncrement();

    /* Open the relation. */
    pg_operator_desc = heap_open(OperatorRelationId, RowExclusiveLock);

    /* Get a writable copy of the commutator's tuple. */
    if (OidIsValid(commId))
        tup = SearchSysCacheCopy1(OPEROID, ObjectIdGetDatum(commId));
    else
        tup = NULL;

    /* Update the commutator's tuple if need be. */
    if (HeapTupleIsValid(tup))
    {
        Form_pg_operator t = (Form_pg_operator) GETSTRUCT(tup);
        bool        update_commutator = false;

        /*
         * Out of due caution, we only change the commutator's oprcom field if
         * it has the exact value we expected: InvalidOid when creating an
         * operator, or baseId when dropping one.
         */
        if (isDelete && t->oprcom == baseId)
        {
            t->oprcom = InvalidOid;
            update_commutator = true;
        }
        else if (!isDelete && !OidIsValid(t->oprcom))
        {
            t->oprcom = baseId;
            update_commutator = true;
        }

        /* If any columns were found to need modification, update tuple. */
        if (update_commutator)
        {
            CatalogTupleUpdate(pg_operator_desc, &tup->t_self, tup);

            /*
             * Do CCI to make the updated tuple visible.  We must do this in
             * case the commutator is also the negator.  (Which would be a
             * logic error on the operator definer's part, but that's not a
             * good reason to fail here.)  We would need a CCI anyway in the
             * deletion case for a self-commutator with no negator.
             */
            CommandCounterIncrement();
        }
    }

    /*
     * Similarly find and update the negator, if any.
     */
    if (OidIsValid(negId))
        tup = SearchSysCacheCopy1(OPEROID, ObjectIdGetDatum(negId));
    else
        tup = NULL;

    if (HeapTupleIsValid(tup))
    {
        Form_pg_operator t = (Form_pg_operator) GETSTRUCT(tup);
        bool        update_negator = false;

        /*
         * Out of due caution, we only change the negator's oprnegate field if
         * it has the exact value we expected: InvalidOid when creating an
         * operator, or baseId when dropping one.
         */
        if (isDelete && t->oprnegate == baseId)
        {
            t->oprnegate = InvalidOid;
            update_negator = true;
        }
        else if (!isDelete && !OidIsValid(t->oprnegate))
        {
            t->oprnegate = baseId;
            update_negator = true;
        }

        /* If any columns were found to need modification, update tuple. */
        if (update_negator)
        {
            CatalogTupleUpdate(pg_operator_desc, &tup->t_self, tup);

            /*
             * In the deletion case, do CCI to make the updated tuple visible.
             * We must do this in case the operator is its own negator. (Which
             * would be a logic error on the operator definer's part, but
             * that's not a good reason to fail here.)
             */
            if (isDelete)
                CommandCounterIncrement();
        }
    }

    /* Close relation and release catalog lock. */
    heap_close(pg_operator_desc, RowExclusiveLock);
}

/*
 * Create dependencies for an operator (either a freshly inserted
 * complete operator, a new shell operator, a just-updated shell,
 * or an operator that's being modified by ALTER OPERATOR).
 *
 * NB: the OidIsValid tests in this routine are necessary, in case
 * the given operator is a shell.
 */
ObjectAddress
makeOperatorDependencies(HeapTuple tuple, bool isUpdate)
{
    Form_pg_operator oper = (Form_pg_operator) GETSTRUCT(tuple);
    ObjectAddress myself,
                referenced;

    myself.classId = OperatorRelationId;
    myself.objectId = HeapTupleGetOid(tuple);
    myself.objectSubId = 0;

    /*
     * If we are updating the operator, delete any existing entries, except
     * for extension membership which should remain the same.
     */
    if (isUpdate)
    {
        deleteDependencyRecordsFor(myself.classId, myself.objectId, true);
        deleteSharedDependencyRecordsFor(myself.classId, myself.objectId, 0);
    }

    /* Dependency on namespace */
    if (OidIsValid(oper->oprnamespace))
    {
        referenced.classId = NamespaceRelationId;
        referenced.objectId = oper->oprnamespace;
        referenced.objectSubId = 0;
        recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
    }

    /* Dependency on left type */
    if (OidIsValid(oper->oprleft))
    {
        referenced.classId = TypeRelationId;
        referenced.objectId = oper->oprleft;
        referenced.objectSubId = 0;
        recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
    }

    /* Dependency on right type */
    if (OidIsValid(oper->oprright))
    {
        referenced.classId = TypeRelationId;
        referenced.objectId = oper->oprright;
        referenced.objectSubId = 0;
        recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
    }

    /* Dependency on result type */
    if (OidIsValid(oper->oprresult))
    {
        referenced.classId = TypeRelationId;
        referenced.objectId = oper->oprresult;
        referenced.objectSubId = 0;
        recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
    }

    /*
     * NOTE: we do not consider the operator to depend on the associated
     * operators oprcom and oprnegate. We would not want to delete this
     * operator if those go away, but only reset the link fields; which is not
     * a function that the dependency code can presently handle.  (Something
     * could perhaps be done with objectSubId though.)  For now, it's okay to
     * let those links dangle if a referenced operator is removed.
     */

    /* Dependency on implementation function */
    if (OidIsValid(oper->oprcode))
    {
        referenced.classId = ProcedureRelationId;
        referenced.objectId = oper->oprcode;
        referenced.objectSubId = 0;
        recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
    }

    /* Dependency on restriction selectivity function */
    if (OidIsValid(oper->oprrest))
    {
        referenced.classId = ProcedureRelationId;
        referenced.objectId = oper->oprrest;
        referenced.objectSubId = 0;
        recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
    }

    /* Dependency on join selectivity function */
    if (OidIsValid(oper->oprjoin))
    {
        referenced.classId = ProcedureRelationId;
        referenced.objectId = oper->oprjoin;
        referenced.objectSubId = 0;
        recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
    }

    /* Dependency on owner */
    recordDependencyOnOwner(OperatorRelationId, HeapTupleGetOid(tuple),
                            oper->oprowner);

    /* Dependency on extension */
    recordDependencyOnCurrentExtension(&myself, true);

    return myself;
}