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PostgreSQL provides set of template index access methods, where opclasses have much freedom in the semantics of indexing. These index AMs are GiST, GIN, SP-GiST and BRIN. There opclasses define representation of keys, operations on them and supported search strategies. So, it's natural that opclasses may be faced some tradeoffs, which require user-side decision. This commit implements opclass parameters allowing users to set some values, which tell opclass how to index the particular dataset. This commit doesn't introduce new storage in system catalog. Instead it uses pg_attribute.attoptions, which is used for table column storage options but unused for index attributes. In order to evade changing signature of each opclass support function, we implement unified way to pass options to opclass support functions. Options are set to fn_expr as the constant bytea expression. It's possible due to the fact that opclass support functions are executed outside of expressions, so fn_expr is unused for them. This commit comes with some examples of opclass options usage. We parametrize signature length in GiST. That applies to multiple opclasses: tsvector_ops, gist__intbig_ops, gist_ltree_ops, gist__ltree_ops, gist_trgm_ops and gist_hstore_ops. Also we parametrize maximum number of integer ranges for gist__int_ops. However, the main future usage of this feature is expected to be json, where users would be able to specify which way to index particular json parts. Catversion is bumped. Discussion: https://postgr.es/m/d22c3a18-31c7-1879-fc11-4c1ce2f5e5af%40postgrespro.ru Author: Nikita Glukhov, revised by me Reviwed-by: Nikolay Shaplov, Robert Haas, Tom Lane, Tomas Vondra, Alvaro Herrera
498 lines
13 KiB
C
498 lines
13 KiB
C
/*-------------------------------------------------------------------------
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*
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* blutils.c
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* Bloom index utilities.
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*
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* Portions Copyright (c) 2016-2020, PostgreSQL Global Development Group
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* Portions Copyright (c) 1990-1993, Regents of the University of California
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*
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* IDENTIFICATION
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* contrib/bloom/blutils.c
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*
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*-------------------------------------------------------------------------
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*/
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#include "postgres.h"
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#include "access/amapi.h"
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#include "access/generic_xlog.h"
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#include "access/reloptions.h"
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#include "bloom.h"
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#include "catalog/index.h"
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#include "commands/vacuum.h"
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#include "miscadmin.h"
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#include "storage/bufmgr.h"
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#include "storage/freespace.h"
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#include "storage/indexfsm.h"
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#include "storage/lmgr.h"
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#include "utils/memutils.h"
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/* Signature dealing macros - note i is assumed to be of type int */
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#define GETWORD(x,i) ( *( (BloomSignatureWord *)(x) + ( (i) / SIGNWORDBITS ) ) )
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#define CLRBIT(x,i) GETWORD(x,i) &= ~( 0x01 << ( (i) % SIGNWORDBITS ) )
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#define SETBIT(x,i) GETWORD(x,i) |= ( 0x01 << ( (i) % SIGNWORDBITS ) )
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#define GETBIT(x,i) ( (GETWORD(x,i) >> ( (i) % SIGNWORDBITS )) & 0x01 )
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PG_FUNCTION_INFO_V1(blhandler);
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/* Kind of relation options for bloom index */
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static relopt_kind bl_relopt_kind;
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/* parse table for fillRelOptions */
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static relopt_parse_elt bl_relopt_tab[INDEX_MAX_KEYS + 1];
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static int32 myRand(void);
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static void mySrand(uint32 seed);
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/*
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* Module initialize function: initialize info about Bloom relation options.
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*
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* Note: keep this in sync with makeDefaultBloomOptions().
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*/
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void
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_PG_init(void)
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{
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int i;
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char buf[16];
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bl_relopt_kind = add_reloption_kind();
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/* Option for length of signature */
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add_int_reloption(bl_relopt_kind, "length",
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"Length of signature in bits",
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DEFAULT_BLOOM_LENGTH, 1, MAX_BLOOM_LENGTH,
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AccessExclusiveLock);
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bl_relopt_tab[0].optname = "length";
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bl_relopt_tab[0].opttype = RELOPT_TYPE_INT;
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bl_relopt_tab[0].offset = offsetof(BloomOptions, bloomLength);
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/* Number of bits for each possible index column: col1, col2, ... */
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for (i = 0; i < INDEX_MAX_KEYS; i++)
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{
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snprintf(buf, sizeof(buf), "col%d", i + 1);
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add_int_reloption(bl_relopt_kind, buf,
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"Number of bits generated for each index column",
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DEFAULT_BLOOM_BITS, 1, MAX_BLOOM_BITS,
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AccessExclusiveLock);
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bl_relopt_tab[i + 1].optname = MemoryContextStrdup(TopMemoryContext,
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buf);
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bl_relopt_tab[i + 1].opttype = RELOPT_TYPE_INT;
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bl_relopt_tab[i + 1].offset = offsetof(BloomOptions, bitSize[0]) + sizeof(int) * i;
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}
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}
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/*
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* Construct a default set of Bloom options.
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*/
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static BloomOptions *
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makeDefaultBloomOptions(void)
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{
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BloomOptions *opts;
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int i;
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opts = (BloomOptions *) palloc0(sizeof(BloomOptions));
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/* Convert DEFAULT_BLOOM_LENGTH from # of bits to # of words */
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opts->bloomLength = (DEFAULT_BLOOM_LENGTH + SIGNWORDBITS - 1) / SIGNWORDBITS;
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for (i = 0; i < INDEX_MAX_KEYS; i++)
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opts->bitSize[i] = DEFAULT_BLOOM_BITS;
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SET_VARSIZE(opts, sizeof(BloomOptions));
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return opts;
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}
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/*
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* Bloom handler function: return IndexAmRoutine with access method parameters
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* and callbacks.
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*/
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Datum
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blhandler(PG_FUNCTION_ARGS)
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{
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IndexAmRoutine *amroutine = makeNode(IndexAmRoutine);
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amroutine->amstrategies = BLOOM_NSTRATEGIES;
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amroutine->amsupport = BLOOM_NPROC;
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amroutine->amoptsprocnum = BLOOM_OPTIONS_PROC;
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amroutine->amcanorder = false;
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amroutine->amcanorderbyop = false;
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amroutine->amcanbackward = false;
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amroutine->amcanunique = false;
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amroutine->amcanmulticol = true;
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amroutine->amoptionalkey = true;
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amroutine->amsearcharray = false;
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amroutine->amsearchnulls = false;
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amroutine->amstorage = false;
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amroutine->amclusterable = false;
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amroutine->ampredlocks = false;
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amroutine->amcanparallel = false;
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amroutine->amcaninclude = false;
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amroutine->amusemaintenanceworkmem = false;
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amroutine->amparallelvacuumoptions =
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VACUUM_OPTION_PARALLEL_BULKDEL | VACUUM_OPTION_PARALLEL_CLEANUP;
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amroutine->amkeytype = InvalidOid;
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amroutine->ambuild = blbuild;
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amroutine->ambuildempty = blbuildempty;
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amroutine->aminsert = blinsert;
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amroutine->ambulkdelete = blbulkdelete;
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amroutine->amvacuumcleanup = blvacuumcleanup;
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amroutine->amcanreturn = NULL;
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amroutine->amcostestimate = blcostestimate;
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amroutine->amoptions = bloptions;
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amroutine->amproperty = NULL;
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amroutine->ambuildphasename = NULL;
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amroutine->amvalidate = blvalidate;
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amroutine->ambeginscan = blbeginscan;
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amroutine->amrescan = blrescan;
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amroutine->amgettuple = NULL;
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amroutine->amgetbitmap = blgetbitmap;
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amroutine->amendscan = blendscan;
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amroutine->ammarkpos = NULL;
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amroutine->amrestrpos = NULL;
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amroutine->amestimateparallelscan = NULL;
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amroutine->aminitparallelscan = NULL;
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amroutine->amparallelrescan = NULL;
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PG_RETURN_POINTER(amroutine);
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}
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/*
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* Fill BloomState structure for particular index.
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*/
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void
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initBloomState(BloomState *state, Relation index)
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{
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int i;
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state->nColumns = index->rd_att->natts;
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/* Initialize hash function for each attribute */
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for (i = 0; i < index->rd_att->natts; i++)
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{
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fmgr_info_copy(&(state->hashFn[i]),
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index_getprocinfo(index, i + 1, BLOOM_HASH_PROC),
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CurrentMemoryContext);
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state->collations[i] = index->rd_indcollation[i];
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}
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/* Initialize amcache if needed with options from metapage */
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if (!index->rd_amcache)
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{
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Buffer buffer;
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Page page;
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BloomMetaPageData *meta;
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BloomOptions *opts;
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opts = MemoryContextAlloc(index->rd_indexcxt, sizeof(BloomOptions));
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buffer = ReadBuffer(index, BLOOM_METAPAGE_BLKNO);
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LockBuffer(buffer, BUFFER_LOCK_SHARE);
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page = BufferGetPage(buffer);
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if (!BloomPageIsMeta(page))
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elog(ERROR, "Relation is not a bloom index");
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meta = BloomPageGetMeta(BufferGetPage(buffer));
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if (meta->magickNumber != BLOOM_MAGICK_NUMBER)
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elog(ERROR, "Relation is not a bloom index");
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*opts = meta->opts;
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UnlockReleaseBuffer(buffer);
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index->rd_amcache = (void *) opts;
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}
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memcpy(&state->opts, index->rd_amcache, sizeof(state->opts));
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state->sizeOfBloomTuple = BLOOMTUPLEHDRSZ +
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sizeof(BloomSignatureWord) * state->opts.bloomLength;
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}
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/*
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* Random generator copied from FreeBSD. Using own random generator here for
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* two reasons:
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*
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* 1) In this case random numbers are used for on-disk storage. Usage of
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* PostgreSQL number generator would obstruct it from all possible changes.
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* 2) Changing seed of PostgreSQL random generator would be undesirable side
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* effect.
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*/
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static int32 next;
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static int32
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myRand(void)
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{
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/*----------
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* Compute x = (7^5 * x) mod (2^31 - 1)
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* without overflowing 31 bits:
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* (2^31 - 1) = 127773 * (7^5) + 2836
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* From "Random number generators: good ones are hard to find",
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* Park and Miller, Communications of the ACM, vol. 31, no. 10,
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* October 1988, p. 1195.
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*----------
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*/
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int32 hi,
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lo,
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x;
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/* Must be in [1, 0x7ffffffe] range at this point. */
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hi = next / 127773;
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lo = next % 127773;
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x = 16807 * lo - 2836 * hi;
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if (x < 0)
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x += 0x7fffffff;
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next = x;
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/* Transform to [0, 0x7ffffffd] range. */
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return (x - 1);
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}
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static void
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mySrand(uint32 seed)
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{
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next = seed;
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/* Transform to [1, 0x7ffffffe] range. */
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next = (next % 0x7ffffffe) + 1;
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}
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/*
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* Add bits of given value to the signature.
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*/
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void
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signValue(BloomState *state, BloomSignatureWord *sign, Datum value, int attno)
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{
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uint32 hashVal;
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int nBit,
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j;
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/*
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* init generator with "column's" number to get "hashed" seed for new
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* value. We don't want to map the same numbers from different columns
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* into the same bits!
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*/
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mySrand(attno);
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/*
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* Init hash sequence to map our value into bits. the same values in
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* different columns will be mapped into different bits because of step
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* above
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*/
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hashVal = DatumGetInt32(FunctionCall1Coll(&state->hashFn[attno], state->collations[attno], value));
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mySrand(hashVal ^ myRand());
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for (j = 0; j < state->opts.bitSize[attno]; j++)
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{
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/* prevent multiple evaluation in SETBIT macro */
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nBit = myRand() % (state->opts.bloomLength * SIGNWORDBITS);
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SETBIT(sign, nBit);
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}
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}
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/*
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* Make bloom tuple from values.
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*/
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BloomTuple *
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BloomFormTuple(BloomState *state, ItemPointer iptr, Datum *values, bool *isnull)
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{
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int i;
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BloomTuple *res = (BloomTuple *) palloc0(state->sizeOfBloomTuple);
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res->heapPtr = *iptr;
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/* Blooming each column */
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for (i = 0; i < state->nColumns; i++)
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{
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/* skip nulls */
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if (isnull[i])
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continue;
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signValue(state, res->sign, values[i], i);
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}
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return res;
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}
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/*
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* Add new bloom tuple to the page. Returns true if new tuple was successfully
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* added to the page. Returns false if it doesn't fit on the page.
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*/
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bool
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BloomPageAddItem(BloomState *state, Page page, BloomTuple *tuple)
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{
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BloomTuple *itup;
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BloomPageOpaque opaque;
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Pointer ptr;
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/* We shouldn't be pointed to an invalid page */
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Assert(!PageIsNew(page) && !BloomPageIsDeleted(page));
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/* Does new tuple fit on the page? */
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if (BloomPageGetFreeSpace(state, page) < state->sizeOfBloomTuple)
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return false;
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/* Copy new tuple to the end of page */
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opaque = BloomPageGetOpaque(page);
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itup = BloomPageGetTuple(state, page, opaque->maxoff + 1);
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memcpy((Pointer) itup, (Pointer) tuple, state->sizeOfBloomTuple);
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/* Adjust maxoff and pd_lower */
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opaque->maxoff++;
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ptr = (Pointer) BloomPageGetTuple(state, page, opaque->maxoff + 1);
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((PageHeader) page)->pd_lower = ptr - page;
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/* Assert we didn't overrun available space */
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Assert(((PageHeader) page)->pd_lower <= ((PageHeader) page)->pd_upper);
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return true;
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}
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/*
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* Allocate a new page (either by recycling, or by extending the index file)
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* The returned buffer is already pinned and exclusive-locked
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* Caller is responsible for initializing the page by calling BloomInitPage
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*/
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Buffer
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BloomNewBuffer(Relation index)
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{
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Buffer buffer;
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bool needLock;
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/* First, try to get a page from FSM */
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for (;;)
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{
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BlockNumber blkno = GetFreeIndexPage(index);
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if (blkno == InvalidBlockNumber)
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break;
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buffer = ReadBuffer(index, blkno);
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/*
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* We have to guard against the possibility that someone else already
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* recycled this page; the buffer may be locked if so.
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*/
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if (ConditionalLockBuffer(buffer))
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{
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Page page = BufferGetPage(buffer);
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if (PageIsNew(page))
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return buffer; /* OK to use, if never initialized */
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if (BloomPageIsDeleted(page))
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return buffer; /* OK to use */
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LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
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}
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/* Can't use it, so release buffer and try again */
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ReleaseBuffer(buffer);
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}
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/* Must extend the file */
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needLock = !RELATION_IS_LOCAL(index);
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if (needLock)
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LockRelationForExtension(index, ExclusiveLock);
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buffer = ReadBuffer(index, P_NEW);
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LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
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if (needLock)
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UnlockRelationForExtension(index, ExclusiveLock);
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return buffer;
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}
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/*
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* Initialize any page of a bloom index.
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*/
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void
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BloomInitPage(Page page, uint16 flags)
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{
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BloomPageOpaque opaque;
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PageInit(page, BLCKSZ, sizeof(BloomPageOpaqueData));
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opaque = BloomPageGetOpaque(page);
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memset(opaque, 0, sizeof(BloomPageOpaqueData));
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opaque->flags = flags;
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opaque->bloom_page_id = BLOOM_PAGE_ID;
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}
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/*
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* Fill in metapage for bloom index.
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*/
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void
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BloomFillMetapage(Relation index, Page metaPage)
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{
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BloomOptions *opts;
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BloomMetaPageData *metadata;
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/*
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* Choose the index's options. If reloptions have been assigned, use
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* those, otherwise create default options.
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*/
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opts = (BloomOptions *) index->rd_options;
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if (!opts)
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opts = makeDefaultBloomOptions();
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/*
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* Initialize contents of meta page, including a copy of the options,
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* which are now frozen for the life of the index.
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*/
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BloomInitPage(metaPage, BLOOM_META);
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metadata = BloomPageGetMeta(metaPage);
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memset(metadata, 0, sizeof(BloomMetaPageData));
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metadata->magickNumber = BLOOM_MAGICK_NUMBER;
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metadata->opts = *opts;
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((PageHeader) metaPage)->pd_lower += sizeof(BloomMetaPageData);
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/* If this fails, probably FreeBlockNumberArray size calc is wrong: */
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Assert(((PageHeader) metaPage)->pd_lower <= ((PageHeader) metaPage)->pd_upper);
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}
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/*
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* Initialize metapage for bloom index.
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*/
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void
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BloomInitMetapage(Relation index)
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{
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Buffer metaBuffer;
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Page metaPage;
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GenericXLogState *state;
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/*
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* Make a new page; since it is first page it should be associated with
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* block number 0 (BLOOM_METAPAGE_BLKNO).
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*/
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metaBuffer = BloomNewBuffer(index);
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Assert(BufferGetBlockNumber(metaBuffer) == BLOOM_METAPAGE_BLKNO);
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/* Initialize contents of meta page */
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state = GenericXLogStart(index);
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metaPage = GenericXLogRegisterBuffer(state, metaBuffer,
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GENERIC_XLOG_FULL_IMAGE);
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BloomFillMetapage(index, metaPage);
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GenericXLogFinish(state);
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UnlockReleaseBuffer(metaBuffer);
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}
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/*
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* Parse reloptions for bloom index, producing a BloomOptions struct.
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*/
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bytea *
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bloptions(Datum reloptions, bool validate)
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{
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BloomOptions *rdopts;
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/* Parse the user-given reloptions */
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rdopts = (BloomOptions *) build_reloptions(reloptions, validate,
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bl_relopt_kind,
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sizeof(BloomOptions),
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bl_relopt_tab,
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lengthof(bl_relopt_tab));
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/* Convert signature length from # of bits to # to words, rounding up */
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if (rdopts)
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rdopts->bloomLength = (rdopts->bloomLength + SIGNWORDBITS - 1) / SIGNWORDBITS;
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return (bytea *) rdopts;
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}
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