toast_internals.h

Go to the documentation of this file.

/*-------------------------------------------------------------------------
 *
 * toast_internals.h
 *    Internal definitions for the TOAST system.
 *
 * Copyright (c) 2000-2024, PostgreSQL Global Development Group
 *
 * src/include/access/toast_internals.h
 *
 *-------------------------------------------------------------------------
 */
#ifndef TOAST_INTERNALS_H
#define TOAST_INTERNALS_H
 
#include "access/toast_compression.h"
#include "storage/lockdefs.h"
#include "utils/relcache.h"
#include "utils/snapshot.h"
 
/*
 *  The information at the start of the compressed toast data.
 */
typedef struct toast_compress_header
{
    int32       vl_len_;        /* varlena header (do not touch directly!) */
    uint32      tcinfo;         /* 2 bits for compression method and 30 bits
                                 * external size; see va_extinfo */
} toast_compress_header;
 
/*
 * Utilities for manipulation of header information for compressed
 * toast entries.
 */
#define TOAST_COMPRESS_EXTSIZE(ptr) \
    (((toast_compress_header *) (ptr))->tcinfo & VARLENA_EXTSIZE_MASK)
#define TOAST_COMPRESS_METHOD(ptr) \
    (((toast_compress_header *) (ptr))->tcinfo >> VARLENA_EXTSIZE_BITS)
 
#define TOAST_COMPRESS_SET_SIZE_AND_COMPRESS_METHOD(ptr, len, cm_method) \
    do { \
        Assert((len) > 0 && (len) <= VARLENA_EXTSIZE_MASK); \
        Assert((cm_method) == TOAST_PGLZ_COMPRESSION_ID || \
               (cm_method) == TOAST_LZ4_COMPRESSION_ID); \
        ((toast_compress_header *) (ptr))->tcinfo = \
            (len) | ((uint32) (cm_method) << VARLENA_EXTSIZE_BITS); \
    } while (0)
 
extern Datum toast_compress_datum(Datum value, char cmethod);
extern Oid  toast_get_valid_index(Oid toastoid, LOCKMODE lock);
 
extern void toast_delete_datum(Relation rel, Datum value, bool is_speculative);
extern Datum toast_save_datum(Relation rel, Datum value,
                              struct varlena *oldexternal, int options);
 
extern int  toast_open_indexes(Relation toastrel,
                               LOCKMODE lock,
                               Relation **toastidxs,
                               int *num_indexes);
extern void toast_close_indexes(Relation *toastidxs, int num_indexes,
                                LOCKMODE lock);
extern void init_toast_snapshot(Snapshot toast_snapshot);
 
#endif                          /* TOAST_INTERNALS_H */