Bloom index contrib module

Module provides new access method. It is actually a simple Bloom filter
implemented as pgsql's index. It could give some benefits on search
with large number of columns.

Module is a single way to test generic WAL interface committed earlier.

Author: Teodor Sigaev, Alexander Korotkov
Reviewers: Aleksander Alekseev, Michael Paquier, Jim Nasby

contrib/bloom/blinsert.c

@@ -0,0 +1,313 @@
+/*-------------------------------------------------------------------------
+ *
+ * blinsert.c
+ *		Bloom index build and insert functions.
+ *
+ * Copyright (c) 2016, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/bloom/blinsert.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/genam.h"
+#include "access/generic_xlog.h"
+#include "catalog/index.h"
+#include "miscadmin.h"
+#include "storage/bufmgr.h"
+#include "storage/indexfsm.h"
+#include "utils/memutils.h"
+#include "utils/rel.h"
+
+#include "bloom.h"
+
+PG_MODULE_MAGIC;
+
+/*
+ * State of bloom index build.  We accumulate one page data here before
+ * flushing it to buffer manager.
+ */
+typedef struct
+{
+	BloomState	blstate;		/* bloom index state */
+	MemoryContext tmpCtx;		/* temporary memory context reset after
+								 * each tuple */
+	char		data[BLCKSZ];	/* cached page */
+	int64		count;			/* number of tuples in cached page */
+}	BloomBuildState;
+
+/*
+ * Flush page cached in BloomBuildState.
+ */
+static void
+flushCachedPage(Relation index, BloomBuildState *buildstate)
+{
+	Page		page;
+	Buffer		buffer = BloomNewBuffer(index);
+	GenericXLogState *state;
+
+	state = GenericXLogStart(index);
+	page = GenericXLogRegister(state, buffer, true);
+	memcpy(page, buildstate->data, BLCKSZ);
+	GenericXLogFinish(state);
+	UnlockReleaseBuffer(buffer);
+}
+
+/*
+ * (Re)initialize cached page in BloomBuildState.
+ */
+static void
+initCachedPage(BloomBuildState *buildstate)
+{
+	memset(buildstate->data, 0, BLCKSZ);
+	BloomInitPage(buildstate->data, 0);
+	buildstate->count = 0;
+}
+
+/*
+ * Per-tuple callback from IndexBuildHeapScan.
+ */
+static void
+bloomBuildCallback(Relation index, HeapTuple htup, Datum *values,
+				   bool *isnull, bool tupleIsAlive, void *state)
+{
+	BloomBuildState *buildstate = (BloomBuildState *) state;
+	MemoryContext oldCtx;
+	BloomTuple *itup;
+
+	oldCtx = MemoryContextSwitchTo(buildstate->tmpCtx);
+
+	itup = BloomFormTuple(&buildstate->blstate, &htup->t_self, values, isnull);
+
+	/* Try to add next item to cached page */
+	if (BloomPageAddItem(&buildstate->blstate, buildstate->data, itup))
+	{
+		/* Next item was added successfully */
+		buildstate->count++;
+	}
+	else
+	{
+		/* Cached page is full, flush it out and make a new one */
+		flushCachedPage(index, buildstate);
+
+		CHECK_FOR_INTERRUPTS();
+
+		initCachedPage(buildstate);
+
+		if (BloomPageAddItem(&buildstate->blstate, buildstate->data, itup) == false)
+		{
+			/* We shouldn't be here since we're inserting to the empty page */
+			elog(ERROR, "can not add new tuple");
+		}
+	}
+
+	MemoryContextSwitchTo(oldCtx);
+	MemoryContextReset(buildstate->tmpCtx);
+}
+
+/*
+ * Build a new bloom index.
+ */
+IndexBuildResult *
+blbuild(Relation heap, Relation index, IndexInfo *indexInfo)
+{
+	IndexBuildResult *result;
+	double		reltuples;
+	BloomBuildState buildstate;
+
+	if (RelationGetNumberOfBlocks(index) != 0)
+		elog(ERROR, "index \"%s\" already contains data",
+			 RelationGetRelationName(index));
+
+	/* Initialize the meta page */
+	BloomInitMetapage(index);
+
+	/* Initialize the bloom build state */
+	memset(&buildstate, 0, sizeof(buildstate));
+	initBloomState(&buildstate.blstate, index);
+	buildstate.tmpCtx = AllocSetContextCreate(CurrentMemoryContext,
+											  "Bloom build temporary context",
+											  ALLOCSET_DEFAULT_MINSIZE,
+											  ALLOCSET_DEFAULT_INITSIZE,
+											  ALLOCSET_DEFAULT_MAXSIZE);
+	initCachedPage(&buildstate);
+
+	/* Do the heap scan */
+	reltuples = IndexBuildHeapScan(heap, index, indexInfo, true,
+								   bloomBuildCallback, (void *) &buildstate);
+
+	/*
+	 * There are could be some items in cached page.  Flush this page
+	 * if needed.
+	 */
+	if (buildstate.count > 0)
+		flushCachedPage(index, &buildstate);
+
+	MemoryContextDelete(buildstate.tmpCtx);
+
+	result = (IndexBuildResult *) palloc(sizeof(IndexBuildResult));
+	result->heap_tuples = result->index_tuples = reltuples;
+
+	return result;
+}
+
+/*
+ * Build an empty bloom index in the initialization fork.
+ */
+void
+blbuildempty(Relation index)
+{
+	if (RelationGetNumberOfBlocks(index) != 0)
+		elog(ERROR, "index \"%s\" already contains data",
+			 RelationGetRelationName(index));
+
+	/* Initialize the meta page */
+	BloomInitMetapage(index);
+}
+
+/*
+ * Insert new tuple to the bloom index.
+ */
+bool
+blinsert(Relation index, Datum *values, bool *isnull,
+		 ItemPointer ht_ctid, Relation heapRel, IndexUniqueCheck checkUnique)
+{
+	BloomState	blstate;
+	BloomTuple *itup;
+	MemoryContext oldCtx;
+	MemoryContext insertCtx;
+	BloomMetaPageData *metaData;
+	Buffer		buffer,
+				metaBuffer;
+	Page		page,
+				metaPage;
+	BlockNumber blkno = InvalidBlockNumber;
+	OffsetNumber nStart;
+	GenericXLogState *state;
+
+	insertCtx = AllocSetContextCreate(CurrentMemoryContext,
+									  "Bloom insert temporary context",
+									  ALLOCSET_DEFAULT_MINSIZE,
+									  ALLOCSET_DEFAULT_INITSIZE,
+									  ALLOCSET_DEFAULT_MAXSIZE);
+
+	oldCtx = MemoryContextSwitchTo(insertCtx);
+
+	initBloomState(&blstate, index);
+	itup = BloomFormTuple(&blstate, ht_ctid, values, isnull);
+
+	/*
+	 * At first, try to insert new tuple to the first page in notFullPage
+	 * array.  If success we don't need to modify the meta page.
+	 */
+	metaBuffer = ReadBuffer(index, BLOOM_METAPAGE_BLKNO);
+	LockBuffer(metaBuffer, BUFFER_LOCK_SHARE);
+	metaData = BloomPageGetMeta(BufferGetPage(metaBuffer));
+
+	if (metaData->nEnd > metaData->nStart)
+	{
+		Page		page;
+
+		blkno = metaData->notFullPage[metaData->nStart];
+
+		Assert(blkno != InvalidBlockNumber);
+		LockBuffer(metaBuffer, BUFFER_LOCK_UNLOCK);
+
+		buffer = ReadBuffer(index, blkno);
+		LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
+		state = GenericXLogStart(index);
+		page = GenericXLogRegister(state, buffer, false);
+
+		if (BloomPageAddItem(&blstate, page, itup))
+		{
+			GenericXLogFinish(state);
+			UnlockReleaseBuffer(buffer);
+			ReleaseBuffer(metaBuffer);
+			MemoryContextSwitchTo(oldCtx);
+			MemoryContextDelete(insertCtx);
+			return false;
+		}
+		else
+		{
+			GenericXLogAbort(state);
+			UnlockReleaseBuffer(buffer);
+		}
+	}
+	else
+	{
+		/* First page in notFullPage isn't suitable */
+		LockBuffer(metaBuffer, BUFFER_LOCK_UNLOCK);
+	}
+
+	/*
+	 * Try other pages in notFullPage array.  We will have to change nStart in
+	 * metapage.  Thus, grab exclusive lock on metapage.
+	 */
+	LockBuffer(metaBuffer, BUFFER_LOCK_EXCLUSIVE);
+
+	state = GenericXLogStart(index);
+	metaPage = GenericXLogRegister(state, metaBuffer, false);
+	metaData = BloomPageGetMeta(metaPage);
+
+	/*
+	 * Iterate over notFullPage array.  Skip page we already tried first.
+	 */
+	nStart = metaData->nStart;
+	if (metaData->nEnd > nStart &&
+		blkno == metaData->notFullPage[nStart])
+		nStart++;
+
+	while (metaData->nEnd > nStart)
+	{
+		blkno = metaData->notFullPage[nStart];
+		Assert(blkno != InvalidBlockNumber);
+
+		buffer = ReadBuffer(index, blkno);
+		LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
+		page = GenericXLogRegister(state, buffer, false);
+
+		if (BloomPageAddItem(&blstate, page, itup))
+		{
+			metaData->nStart = nStart;
+			GenericXLogFinish(state);
+			UnlockReleaseBuffer(buffer);
+			UnlockReleaseBuffer(metaBuffer);
+			MemoryContextSwitchTo(oldCtx);
+			MemoryContextDelete(insertCtx);
+			return false;
+		}
+		else
+		{
+			GenericXLogUnregister(state, buffer);
+			UnlockReleaseBuffer(buffer);
+		}
+		nStart++;
+	}
+
+	GenericXLogAbort(state);
+
+	/*
+	 * Didn't find place to insert in notFullPage array.  Allocate new page.
+	 */
+	buffer = BloomNewBuffer(index);
+
+	state = GenericXLogStart(index);
+	metaPage = GenericXLogRegister(state, metaBuffer, false);
+	metaData = BloomPageGetMeta(metaPage);
+	page = GenericXLogRegister(state, buffer, true);
+	BloomInitPage(page, 0);
+	BloomPageAddItem(&blstate, page, itup);
+
+	metaData->nStart = 0;
+	metaData->nEnd = 1;
+	metaData->notFullPage[0] = BufferGetBlockNumber(buffer);
+
+	GenericXLogFinish(state);
+
+	UnlockReleaseBuffer(buffer);
+	UnlockReleaseBuffer(metaBuffer);
+
+	return false;
+}