codekingpro/portable-devtools

1/*-------------------------------------------------------------------------2 *3 * itup.h4 *	  POSTGRES index tuple definitions.5 *6 *7 * Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group8 * Portions Copyright (c) 1994, Regents of the University of California9 *10 * src/include/access/itup.h11 *12 *-------------------------------------------------------------------------13 */14#ifndef ITUP_H15#define ITUP_H16 17#include "access/tupdesc.h"18#include "access/tupmacs.h"19#include "storage/bufpage.h"20#include "storage/itemptr.h"21 22/*23 * Index tuple header structure24 *25 * All index tuples start with IndexTupleData.  If the HasNulls bit is set,26 * this is followed by an IndexAttributeBitMapData.  The index attribute27 * values follow, beginning at a MAXALIGN boundary.28 *29 * Note that the space allocated for the bitmap does not vary with the number30 * of attributes; that is because we don't have room to store the number of31 * attributes in the header.  Given the MAXALIGN constraint there's no space32 * savings to be had anyway, for usual values of INDEX_MAX_KEYS.33 */34 35typedef struct IndexTupleData36{37	ItemPointerData t_tid;		/* reference TID to heap tuple */38 39	/* ---------------40	 * t_info is laid out in the following fashion:41	 *42	 * 15th (high) bit: has nulls43	 * 14th bit: has var-width attributes44	 * 13th bit: AM-defined meaning45	 * 12-0 bit: size of tuple46	 * ---------------47	 */48 49	unsigned short t_info;		/* various info about tuple */50 51} IndexTupleData;				/* MORE DATA FOLLOWS AT END OF STRUCT */52 53typedef IndexTupleData *IndexTuple;54 55typedef struct IndexAttributeBitMapData56{57	bits8		bits[(INDEX_MAX_KEYS + 8 - 1) / 8];58}			IndexAttributeBitMapData;59 60typedef IndexAttributeBitMapData * IndexAttributeBitMap;61 62/*63 * t_info manipulation macros64 */65#define INDEX_SIZE_MASK 0x1FFF66#define INDEX_AM_RESERVED_BIT 0x2000	/* reserved for index-AM specific67										 * usage */68#define INDEX_VAR_MASK	0x400069#define INDEX_NULL_MASK 0x800070 71#define IndexTupleSize(itup)		((Size) ((itup)->t_info & INDEX_SIZE_MASK))72#define IndexTupleHasNulls(itup)	((((IndexTuple) (itup))->t_info & INDEX_NULL_MASK))73#define IndexTupleHasVarwidths(itup) ((((IndexTuple) (itup))->t_info & INDEX_VAR_MASK))74 75 76/* routines in indextuple.c */77extern IndexTuple index_form_tuple(TupleDesc tupleDescriptor,78								   Datum *values, bool *isnull);79extern IndexTuple index_form_tuple_context(TupleDesc tupleDescriptor,80										   Datum *values, bool *isnull,81										   MemoryContext context);82extern Datum nocache_index_getattr(IndexTuple tup, int attnum,83								   TupleDesc tupleDesc);84extern void index_deform_tuple(IndexTuple tup, TupleDesc tupleDescriptor,85							   Datum *values, bool *isnull);86extern void index_deform_tuple_internal(TupleDesc tupleDescriptor,87										Datum *values, bool *isnull,88										char *tp, bits8 *bp, int hasnulls);89extern IndexTuple CopyIndexTuple(IndexTuple source);90extern IndexTuple index_truncate_tuple(TupleDesc sourceDescriptor,91									   IndexTuple source, int leavenatts);92 93 94/*95 * Takes an infomask as argument (primarily because this needs to be usable96 * at index_form_tuple time so enough space is allocated).97 */98static inline Size99IndexInfoFindDataOffset(unsigned short t_info)100{101	if (!(t_info & INDEX_NULL_MASK))102		return MAXALIGN(sizeof(IndexTupleData));103	else104		return MAXALIGN(sizeof(IndexTupleData) + sizeof(IndexAttributeBitMapData));105}106 107#ifndef FRONTEND108 109/* ----------------110 *		index_getattr111 *112 *		This gets called many times, so we macro the cacheable and NULL113 *		lookups, and call nocache_index_getattr() for the rest.114 *115 * ----------------116 */117static inline Datum118index_getattr(IndexTuple tup, int attnum, TupleDesc tupleDesc, bool *isnull)119{120	Assert(PointerIsValid(isnull));121	Assert(attnum > 0);122 123	*isnull = false;124 125	if (!IndexTupleHasNulls(tup))126	{127		if (TupleDescAttr(tupleDesc, attnum - 1)->attcacheoff >= 0)128		{129			return fetchatt(TupleDescAttr(tupleDesc, attnum - 1),130							(char *) tup + IndexInfoFindDataOffset(tup->t_info)131							+ TupleDescAttr(tupleDesc, attnum - 1)->attcacheoff);132		}133		else134			return nocache_index_getattr(tup, attnum, tupleDesc);135	}136	else137	{138		if (att_isnull(attnum - 1, (bits8 *) tup + sizeof(IndexTupleData)))139		{140			*isnull = true;141			return (Datum) NULL;142		}143		else144			return nocache_index_getattr(tup, attnum, tupleDesc);145	}146}147 148#endif149 150/*151 * MaxIndexTuplesPerPage is an upper bound on the number of tuples that can152 * fit on one index page.  An index tuple must have either data or a null153 * bitmap, so we can safely assume it's at least 1 byte bigger than a bare154 * IndexTupleData struct.  We arrive at the divisor because each tuple155 * must be maxaligned, and it must have an associated line pointer.156 *157 * To be index-type-independent, this does not account for any special space158 * on the page, and is thus conservative.159 *160 * Note: in btree non-leaf pages, the first tuple has no key (it's implicitly161 * minus infinity), thus breaking the "at least 1 byte bigger" assumption.162 * On such a page, N tuples could take one MAXALIGN quantum less space than163 * estimated here, seemingly allowing one more tuple than estimated here.164 * But such a page always has at least MAXALIGN special space, so we're safe.165 */166#define MaxIndexTuplesPerPage	\167	((int) ((BLCKSZ - SizeOfPageHeaderData) / \168			(MAXALIGN(sizeof(IndexTupleData) + 1) + sizeof(ItemIdData))))169 170#endif							/* ITUP_H */171