pg_cast.c

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/*-------------------------------------------------------------------------
 *
 * pg_cast.c
 *    routines to support manipulation of the pg_cast relation
 *
 * Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *    src/backend/catalog/pg_cast.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"
 
#include "access/htup_details.h"
#include "access/table.h"
#include "catalog/catalog.h"
#include "catalog/dependency.h"
#include "catalog/indexing.h"
#include "catalog/objectaccess.h"
#include "catalog/pg_cast.h"
#include "catalog/pg_proc.h"
#include "catalog/pg_type.h"
#include "utils/builtins.h"
#include "utils/rel.h"
#include "utils/syscache.h"
 
/*
 * ----------------------------------------------------------------
 *      CastCreate
 *
 * Forms and inserts catalog tuples for a new cast being created.
 * Caller must have already checked privileges, and done consistency
 * checks on the given datatypes and cast function (if applicable).
 *
 * Since we allow binary coercibility of the datatypes to the cast
 * function's input and result, there could be one or two WITHOUT FUNCTION
 * casts that this one depends on.  We don't record that explicitly
 * in pg_cast, but we still need to make dependencies on those casts.
 *
 * 'behavior' indicates the types of the dependencies that the new
 * cast will have on its input and output types, the cast function,
 * and the other casts if any.
 * ----------------------------------------------------------------
 */
ObjectAddress
CastCreate(Oid sourcetypeid, Oid targettypeid,
           Oid funcid, Oid incastid, Oid outcastid,
           char castcontext, char castmethod, DependencyType behavior)
{
    Relation    relation;
    HeapTuple   tuple;
    Oid         castid;
    Datum       values[Natts_pg_cast];
    bool        nulls[Natts_pg_cast] = {0};
    ObjectAddress myself,
                referenced;
    ObjectAddresses *addrs;
 
    relation = table_open(CastRelationId, RowExclusiveLock);
 
    /*
     * Check for duplicate.  This is just to give a friendly error message,
     * the unique index would catch it anyway (so no need to sweat about race
     * conditions).
     */
    tuple = SearchSysCache2(CASTSOURCETARGET,
                            ObjectIdGetDatum(sourcetypeid),
                            ObjectIdGetDatum(targettypeid));
    if (HeapTupleIsValid(tuple))
        ereport(ERROR,
                (errcode(ERRCODE_DUPLICATE_OBJECT),
                 errmsg("cast from type %s to type %s already exists",
                        format_type_be(sourcetypeid),
                        format_type_be(targettypeid))));
 
    /* ready to go */
    castid = GetNewOidWithIndex(relation, CastOidIndexId, Anum_pg_cast_oid);
    values[Anum_pg_cast_oid - 1] = ObjectIdGetDatum(castid);
    values[Anum_pg_cast_castsource - 1] = ObjectIdGetDatum(sourcetypeid);
    values[Anum_pg_cast_casttarget - 1] = ObjectIdGetDatum(targettypeid);
    values[Anum_pg_cast_castfunc - 1] = ObjectIdGetDatum(funcid);
    values[Anum_pg_cast_castcontext - 1] = CharGetDatum(castcontext);
    values[Anum_pg_cast_castmethod - 1] = CharGetDatum(castmethod);
 
    tuple = heap_form_tuple(RelationGetDescr(relation), values, nulls);
 
    CatalogTupleInsert(relation, tuple);
 
    addrs = new_object_addresses();
 
    /* make dependency entries */
    ObjectAddressSet(myself, CastRelationId, castid);
 
    /* dependency on source type */
    ObjectAddressSet(referenced, TypeRelationId, sourcetypeid);
    add_exact_object_address(&referenced, addrs);
 
    /* dependency on target type */
    ObjectAddressSet(referenced, TypeRelationId, targettypeid);
    add_exact_object_address(&referenced, addrs);
 
    /* dependency on function */
    if (OidIsValid(funcid))
    {
        ObjectAddressSet(referenced, ProcedureRelationId, funcid);
        add_exact_object_address(&referenced, addrs);
    }
 
    /* dependencies on casts required for function */
    if (OidIsValid(incastid))
    {
        ObjectAddressSet(referenced, CastRelationId, incastid);
        add_exact_object_address(&referenced, addrs);
    }
    if (OidIsValid(outcastid))
    {
        ObjectAddressSet(referenced, CastRelationId, outcastid);
        add_exact_object_address(&referenced, addrs);
    }
 
    record_object_address_dependencies(&myself, addrs, behavior);
    free_object_addresses(addrs);
 
    /* dependency on extension */
    recordDependencyOnCurrentExtension(&myself, false);
 
    /* Post creation hook for new cast */
    InvokeObjectPostCreateHook(CastRelationId, castid, 0);
 
    heap_freetuple(tuple);
 
    table_close(relation, RowExclusiveLock);
 
    return myself;
}