src/libpq/include/utils/typcache.h

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/*-------------------------------------------------------------------------
 *
 * typcache.h
 *        Type cache definitions.
 *
 * The type cache exists to speed lookup of certain information about data
 * types that is not directly available from a type's pg_type row.
 *
 * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * $PostgreSQL: pgsql/src/include/utils/typcache.h,v 1.8.2.1 2005/11/22 18:23:29 momjian Exp $
 *
 *-------------------------------------------------------------------------
 */
#ifndef TYPCACHE_H
#define TYPCACHE_H

#include "access/tupdesc.h"
#include "fmgr.h"


typedef struct TypeCacheEntry
{
        /* typeId is the hash lookup key and MUST BE FIRST */
        Oid                     type_id;                /* OID of the data type */

        /* some subsidiary information copied from the pg_type row */
        int16           typlen;
        bool            typbyval;
        char            typalign;
        char            typtype;
        Oid                     typrelid;

        /*
         * Information obtained from opclass entries
         *
         * These will be InvalidOid if no match could be found, or if the
         * information hasn't yet been requested.
         */
        Oid                     btree_opc;              /* OID of the default btree opclass */
        Oid                     hash_opc;               /* OID of the default hash opclass */
        Oid                     eq_opr;                 /* OID of the equality operator */
        Oid                     lt_opr;                 /* OID of the less-than operator */
        Oid                     gt_opr;                 /* OID of the greater-than operator */
        Oid                     cmp_proc;               /* OID of the btree comparison function */

        /*
         * Pre-set-up fmgr call info for the equality operator and the btree
         * comparison function.  These are kept in the type cache to avoid
         * problems with memory leaks in repeated calls to array_eq and array_cmp.
         * There is not currently a need to maintain call info for the lt_opr or
         * gt_opr.
         */
        FmgrInfo        eq_opr_finfo;
        FmgrInfo        cmp_proc_finfo;

        /*
         * Tuple descriptor if it's a composite type (row type).  NULL if not
         * composite or information hasn't yet been requested.  (NOTE: this is
         * actually just a link to information maintained by relcache.c.)
         */
        TupleDesc       tupDesc;
} TypeCacheEntry;

/* Bit flags to indicate which fields a given caller needs to have set */
#define TYPECACHE_EQ_OPR                        0x0001
#define TYPECACHE_LT_OPR                        0x0002
#define TYPECACHE_GT_OPR                        0x0004
#define TYPECACHE_CMP_PROC                      0x0008
#define TYPECACHE_EQ_OPR_FINFO          0x0010
#define TYPECACHE_CMP_PROC_FINFO        0x0020
#define TYPECACHE_TUPDESC                       0x0040

extern TypeCacheEntry *lookup_type_cache(Oid type_id, int flags);

extern TupleDesc lookup_rowtype_tupdesc(Oid type_id, int32 typmod);

extern TupleDesc lookup_rowtype_tupdesc_noerror(Oid type_id, int32 typmod,
                                                           bool noError);

extern void assign_record_type_typmod(TupleDesc tupDesc);

extern void flush_rowtype_cache(Oid type_id);

#endif   /* TYPCACHE_H */