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111 lines
3.7 KiB
C
111 lines
3.7 KiB
C
/*
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* brin_tuple.h
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* Declarations for dealing with BRIN-specific tuples.
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*
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* Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* IDENTIFICATION
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* src/include/access/brin_tuple.h
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*/
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#ifndef BRIN_TUPLE_H
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#define BRIN_TUPLE_H
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#include "access/brin_internal.h"
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#include "access/tupdesc.h"
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/*
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* The BRIN opclasses may register serialization callback, in case the on-disk
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* and in-memory representations differ (e.g. for performance reasons).
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*/
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typedef void (*brin_serialize_callback_type) (BrinDesc *bdesc, Datum src, Datum *dst);
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/*
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* A BRIN index stores one index tuple per page range. Each index tuple
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* has one BrinValues struct for each indexed column; in turn, each BrinValues
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* has (besides the null flags) an array of Datum whose size is determined by
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* the opclass.
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*/
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typedef struct BrinValues
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{
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AttrNumber bv_attno; /* index attribute number */
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bool bv_hasnulls; /* are there any nulls in the page range? */
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bool bv_allnulls; /* are all values nulls in the page range? */
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Datum *bv_values; /* current accumulated values */
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Datum bv_mem_value; /* expanded accumulated values */
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MemoryContext bv_context;
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brin_serialize_callback_type bv_serialize;
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} BrinValues;
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/*
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* This struct is used to represent an in-memory index tuple. The values can
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* only be meaningfully decoded with an appropriate BrinDesc.
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*/
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typedef struct BrinMemTuple
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{
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bool bt_placeholder; /* this is a placeholder tuple */
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BlockNumber bt_blkno; /* heap blkno that the tuple is for */
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MemoryContext bt_context; /* memcxt holding the bt_columns values */
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/* output arrays for brin_deform_tuple: */
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Datum *bt_values; /* values array */
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bool *bt_allnulls; /* allnulls array */
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bool *bt_hasnulls; /* hasnulls array */
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/* not an output array, but must be last */
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BrinValues bt_columns[FLEXIBLE_ARRAY_MEMBER];
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} BrinMemTuple;
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/*
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* An on-disk BRIN tuple. This is possibly followed by a nulls bitmask, with
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* room for 2 null bits (two bits for each indexed column); an opclass-defined
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* number of Datum values for each column follow.
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*/
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typedef struct BrinTuple
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{
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/* heap block number that the tuple is for */
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BlockNumber bt_blkno;
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/* ---------------
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* bt_info is laid out in the following fashion:
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*
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* 7th (high) bit: has nulls
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* 6th bit: is placeholder tuple
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* 5th bit: unused
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* 4-0 bit: offset of data
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* ---------------
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*/
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uint8 bt_info;
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} BrinTuple;
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#define SizeOfBrinTuple (offsetof(BrinTuple, bt_info) + sizeof(uint8))
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/*
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* bt_info manipulation macros
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*/
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#define BRIN_OFFSET_MASK 0x1F
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/* bit 0x20 is not used at present */
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#define BRIN_PLACEHOLDER_MASK 0x40
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#define BRIN_NULLS_MASK 0x80
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#define BrinTupleDataOffset(tup) ((Size) (((BrinTuple *) (tup))->bt_info & BRIN_OFFSET_MASK))
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#define BrinTupleHasNulls(tup) (((((BrinTuple *) (tup))->bt_info & BRIN_NULLS_MASK)) != 0)
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#define BrinTupleIsPlaceholder(tup) (((((BrinTuple *) (tup))->bt_info & BRIN_PLACEHOLDER_MASK)) != 0)
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extern BrinTuple *brin_form_tuple(BrinDesc *brdesc, BlockNumber blkno,
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BrinMemTuple *tuple, Size *size);
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extern BrinTuple *brin_form_placeholder_tuple(BrinDesc *brdesc,
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BlockNumber blkno, Size *size);
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extern void brin_free_tuple(BrinTuple *tuple);
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extern BrinTuple *brin_copy_tuple(BrinTuple *tuple, Size len,
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BrinTuple *dest, Size *destsz);
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extern bool brin_tuples_equal(const BrinTuple *a, Size alen,
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const BrinTuple *b, Size blen);
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extern BrinMemTuple *brin_new_memtuple(BrinDesc *brdesc);
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extern BrinMemTuple *brin_memtuple_initialize(BrinMemTuple *dtuple,
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BrinDesc *brdesc);
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extern BrinMemTuple *brin_deform_tuple(BrinDesc *brdesc,
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BrinTuple *tuple, BrinMemTuple *dMemtuple);
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#endif /* BRIN_TUPLE_H */
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