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/*
* brin_tuple.h
* Declarations for dealing with BRIN-specific tuples.
*
* Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* src/include/access/brin_tuple.h
*/
#ifndef BRIN_TUPLE_H
#define BRIN_TUPLE_H
#include "access/brin_internal.h"
#include "access/tupdesc.h"
/*
* The BRIN opclasses may register serialization callback, in case the on-disk
* and in-memory representations differ (e.g. for performance reasons).
*/
typedef void (*brin_serialize_callback_type) (BrinDesc *bdesc, Datum src, Datum *dst);
/*
* A BRIN index stores one index tuple per page range. Each index tuple
* has one BrinValues struct for each indexed column; in turn, each BrinValues
* has (besides the null flags) an array of Datum whose size is determined by
* the opclass.
*/
typedef struct BrinValues
{
AttrNumber bv_attno; /* index attribute number */
bool bv_hasnulls; /* are there any nulls in the page range? */
bool bv_allnulls; /* are all values nulls in the page range? */
Datum *bv_values; /* current accumulated values */
Datum bv_mem_value; /* expanded accumulated values */
MemoryContext bv_context;
brin_serialize_callback_type bv_serialize;
} BrinValues;
/*
* This struct is used to represent an in-memory index tuple. The values can
* only be meaningfully decoded with an appropriate BrinDesc.
*/
typedef struct BrinMemTuple
{
bool bt_placeholder; /* this is a placeholder tuple */
bool bt_empty_range; /* range represents no tuples */
BlockNumber bt_blkno; /* heap blkno that the tuple is for */
MemoryContext bt_context; /* memcxt holding the bt_columns values */
/* output arrays for brin_deform_tuple: */
Datum *bt_values; /* values array */
bool *bt_allnulls; /* allnulls array */
bool *bt_hasnulls; /* hasnulls array */
/* not an output array, but must be last */
BrinValues bt_columns[FLEXIBLE_ARRAY_MEMBER];
} BrinMemTuple;
/*
* An on-disk BRIN tuple. This is possibly followed by a nulls bitmask, with
* room for 2 null bits (two bits for each indexed column); an opclass-defined
* number of Datum values for each column follow.
*/
typedef struct BrinTuple
{
/* heap block number that the tuple is for */
BlockNumber bt_blkno;
/* ---------------
* bt_info is laid out in the following fashion:
*
* 7th (high) bit: has nulls
* 6th bit: is placeholder tuple
* 5th bit: range is empty
* 4-0 bit: offset of data
* ---------------
*/
uint8 bt_info;
} BrinTuple;
#define SizeOfBrinTuple (offsetof(BrinTuple, bt_info) + sizeof(uint8))
/*
* bt_info manipulation macros
*/
#define BRIN_OFFSET_MASK 0x1F
#define BRIN_EMPTY_RANGE_MASK 0x20
#define BRIN_PLACEHOLDER_MASK 0x40
#define BRIN_NULLS_MASK 0x80
#define BrinTupleDataOffset(tup) ((Size) (((BrinTuple *) (tup))->bt_info & BRIN_OFFSET_MASK))
#define BrinTupleHasNulls(tup) (((((BrinTuple *) (tup))->bt_info & BRIN_NULLS_MASK)) != 0)
#define BrinTupleIsPlaceholder(tup) (((((BrinTuple *) (tup))->bt_info & BRIN_PLACEHOLDER_MASK)) != 0)
#define BrinTupleIsEmptyRange(tup) (((((BrinTuple *) (tup))->bt_info & BRIN_EMPTY_RANGE_MASK)) != 0)
extern BrinTuple *brin_form_tuple(BrinDesc *brdesc, BlockNumber blkno,
BrinMemTuple *tuple, Size *size);
extern BrinTuple *brin_form_placeholder_tuple(BrinDesc *brdesc,
BlockNumber blkno, Size *size);
extern void brin_free_tuple(BrinTuple *tuple);
extern BrinTuple *brin_copy_tuple(BrinTuple *tuple, Size len,
BrinTuple *dest, Size *destsz);
extern bool brin_tuples_equal(const BrinTuple *a, Size alen,
const BrinTuple *b, Size blen);
extern BrinMemTuple *brin_new_memtuple(BrinDesc *brdesc);
extern BrinMemTuple *brin_memtuple_initialize(BrinMemTuple *dtuple,
BrinDesc *brdesc);
extern BrinMemTuple *brin_deform_tuple(BrinDesc *brdesc,
BrinTuple *tuple, BrinMemTuple *dMemtuple);
#endif /* BRIN_TUPLE_H */
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