src/backend/catalog/pg_cast.c

   1 /*-------------------------------------------------------------------------
   2  *
   3  * pg_cast.c
   4  *        routines to support manipulation of the pg_cast relation
   5  *
   6  * Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
   7  * Portions Copyright (c) 1994, Regents of the University of California
   8  *
   9  *
  10  * IDENTIFICATION
  11  *        src/backend/catalog/pg_cast.c
  12  *
  13  *-------------------------------------------------------------------------
  14  */
  15 #include "postgres.h"
  16
  17 #include "access/htup_details.h"
  18 #include "access/table.h"
  19 #include "catalog/catalog.h"
  20 #include "catalog/dependency.h"
  21 #include "catalog/indexing.h"
  22 #include "catalog/objectaccess.h"
  23 #include "catalog/pg_cast.h"
  24 #include "catalog/pg_proc.h"
  25 #include "catalog/pg_type.h"
  26 #include "utils/builtins.h"
  27 #include "utils/rel.h"
  28 #include "utils/syscache.h"
  29
  30 /*
  31  * ----------------------------------------------------------------
  32  *              CastCreate
  33  *
  34  * Forms and inserts catalog tuples for a new cast being created.
  35  * Caller must have already checked privileges, and done consistency
  36  * checks on the given datatypes and cast function (if applicable).
  37  *
  38  * Since we allow binary coercibility of the datatypes to the cast
  39  * function's input and result, there could be one or two WITHOUT FUNCTION
  40  * casts that this one depends on.  We don't record that explicitly
  41  * in pg_cast, but we still need to make dependencies on those casts.
  42  *
  43  * 'behavior' indicates the types of the dependencies that the new
  44  * cast will have on its input and output types, the cast function,
  45  * and the other casts if any.
  46  * ----------------------------------------------------------------
  47  */
  48 ObjectAddress
  49 CastCreate(Oid sourcetypeid, Oid targettypeid,
  50                    Oid funcid, Oid incastid, Oid outcastid,
  51                    char castcontext, char castmethod, DependencyType behavior)
  52 {
  53         Relation        relation;
  54         HeapTuple       tuple;
  55         Oid                     castid;
  56         Datum           values[Natts_pg_cast];
  57         bool            nulls[Natts_pg_cast] = {0};
  58         ObjectAddress myself,
  59                                 referenced;
  60         ObjectAddresses *addrs;
  61
  62         relation = table_open(CastRelationId, RowExclusiveLock);
  63
  64         /*
  65          * Check for duplicate.  This is just to give a friendly error message,
  66          * the unique index would catch it anyway (so no need to sweat about race
  67          * conditions).
  68          */
  69         tuple = SearchSysCache2(CASTSOURCETARGET,
  70                                                         ObjectIdGetDatum(sourcetypeid),
  71                                                         ObjectIdGetDatum(targettypeid));
  72         if (HeapTupleIsValid(tuple))
  73                 ereport(ERROR,
  74                                 (errcode(ERRCODE_DUPLICATE_OBJECT),
  75                                  errmsg("cast from type %s to type %s already exists",
  76                                                 format_type_be(sourcetypeid),
  77                                                 format_type_be(targettypeid))));
  78
  79         /* ready to go */
  80         castid = GetNewOidWithIndex(relation, CastOidIndexId, Anum_pg_cast_oid);
  81         values[Anum_pg_cast_oid - 1] = ObjectIdGetDatum(castid);
  82         values[Anum_pg_cast_castsource - 1] = ObjectIdGetDatum(sourcetypeid);
  83         values[Anum_pg_cast_casttarget - 1] = ObjectIdGetDatum(targettypeid);
  84         values[Anum_pg_cast_castfunc - 1] = ObjectIdGetDatum(funcid);
  85         values[Anum_pg_cast_castcontext - 1] = CharGetDatum(castcontext);
  86         values[Anum_pg_cast_castmethod - 1] = CharGetDatum(castmethod);
  87
  88         tuple = heap_form_tuple(RelationGetDescr(relation), values, nulls);
  89
  90         CatalogTupleInsert(relation, tuple);
  91
  92         addrs = new_object_addresses();
  93
  94         /* make dependency entries */
  95         ObjectAddressSet(myself, CastRelationId, castid);
  96
  97         /* dependency on source type */
  98         ObjectAddressSet(referenced, TypeRelationId, sourcetypeid);
  99         add_exact_object_address(&referenced, addrs);
 100
 101         /* dependency on target type */
 102         ObjectAddressSet(referenced, TypeRelationId, targettypeid);
 103         add_exact_object_address(&referenced, addrs);
 104
 105         /* dependency on function */
 106         if (OidIsValid(funcid))
 107         {
 108                 ObjectAddressSet(referenced, ProcedureRelationId, funcid);
 109                 add_exact_object_address(&referenced, addrs);
 110         }
 111
 112         /* dependencies on casts required for function */
 113         if (OidIsValid(incastid))
 114         {
 115                 ObjectAddressSet(referenced, CastRelationId, incastid);
 116                 add_exact_object_address(&referenced, addrs);
 117         }
 118         if (OidIsValid(outcastid))
 119         {
 120                 ObjectAddressSet(referenced, CastRelationId, outcastid);
 121                 add_exact_object_address(&referenced, addrs);
 122         }
 123
 124         record_object_address_dependencies(&myself, addrs, behavior);
 125         free_object_addresses(addrs);
 126
 127         /* dependency on extension */
 128         recordDependencyOnCurrentExtension(&myself, false);
 129
 130         /* Post creation hook for new cast */
 131         InvokeObjectPostCreateHook(CastRelationId, castid, 0);
 132
 133         heap_freetuple(tuple);
 134
 135         table_close(relation, RowExclusiveLock);
 136
 137         return myself;
 138 }