GIN: Generalized Inverted iNdex.

text[], int4[], Tsearch2 support for GIN.

src/backend/access/gin/ginutil.c

@@ -0,0 +1,203 @@
+/*-------------------------------------------------------------------------
+ *
+ * ginutil.c
+ *    utilities routines for the postgres inverted index access method.
+ *
+ *
+ * Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * IDENTIFICATION
+ *          $PostgreSQL: pgsql/src/backend/access/gin/ginutil.c,v 1.1 2006/05/02 11:28:54 teodor Exp $
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+#include "access/genam.h"
+#include "access/gin.h"
+#include "access/heapam.h"
+#include "catalog/index.h"
+#include "miscadmin.h"
+#include "storage/freespace.h"
+
+void 
+initGinState( GinState *state, Relation index ) {
+	if ( index->rd_att->natts != 1 )
+			elog(ERROR, "numberOfAttributes %d != 1",
+					index->rd_att->natts);
+	
+	state->tupdesc = index->rd_att;
+
+	fmgr_info_copy(&(state->compareFn),
+			index_getprocinfo(index, 1, GIN_COMPARE_PROC),
+			CurrentMemoryContext);
+	fmgr_info_copy(&(state->extractValueFn),
+			index_getprocinfo(index, 1, GIN_EXTRACTVALUE_PROC),
+			CurrentMemoryContext);
+	fmgr_info_copy(&(state->extractQueryFn),
+			index_getprocinfo(index, 1, GIN_EXTRACTQUERY_PROC),
+			CurrentMemoryContext);
+	fmgr_info_copy(&(state->consistentFn),
+			index_getprocinfo(index, 1, GIN_CONSISTENT_PROC),
+			CurrentMemoryContext);
+}
+
+/*
+ * Allocate a new page (either by recycling, or by extending the index file)
+ * The returned buffer is already pinned and exclusive-locked
+ * Caller is responsible for initializing the page by calling GinInitBuffer
+ */
+
+Buffer
+GinNewBuffer(Relation index) {
+	Buffer	buffer;
+	bool	needLock;
+
+	/* First, try to get a page from FSM */
+	for(;;) {
+		BlockNumber blkno = GetFreeIndexPage(&index->rd_node);
+		if (blkno == InvalidBlockNumber)
+			break;
+
+		buffer = ReadBuffer(index, blkno);
+
+		/*
+		 * We have to guard against the possibility that someone else already
+		 * recycled this page; the buffer may be locked if so.
+		 */
+		 if (ConditionalLockBuffer(buffer)) {
+			Page        page = BufferGetPage(buffer);
+
+			if (PageIsNew(page))
+				return buffer;  /* OK to use, if never initialized */
+
+			if (GinPageIsDeleted(page))
+				return buffer;  /* OK to use */
+
+			LockBuffer(buffer, GIN_UNLOCK);
+		}
+
+		/* Can't use it, so release buffer and try again */
+		ReleaseBuffer(buffer);
+	}
+
+	/* Must extend the file */
+	needLock = !RELATION_IS_LOCAL(index);
+	if (needLock)
+		LockRelationForExtension(index, ExclusiveLock);
+
+	buffer = ReadBuffer(index, P_NEW);
+	LockBuffer(buffer, GIN_EXCLUSIVE);
+
+	if (needLock)
+		UnlockRelationForExtension(index, ExclusiveLock);
+
+	return buffer;
+}
+
+void
+GinInitPage(Page page, uint32 f, Size pageSize) {
+	GinPageOpaque opaque;
+
+	PageInit(page, pageSize, sizeof(GinPageOpaqueData));
+
+	opaque = GinPageGetOpaque(page);
+	memset( opaque, 0, sizeof(GinPageOpaqueData) );
+	opaque->flags = f;   
+	opaque->rightlink = InvalidBlockNumber;
+}
+
+void
+GinInitBuffer(Buffer b, uint32 f) {
+	GinInitPage( BufferGetPage(b), f, BufferGetPageSize(b) );
+}
+
+int
+compareEntries(GinState *ginstate, Datum a, Datum b) {
+	return DatumGetInt32(
+		FunctionCall2(
+			&ginstate->compareFn,
+			a, b
+		)
+	);
+}
+
+static FmgrInfo* cmpDatumPtr=NULL;
+static bool needUnique = FALSE;
+
+static int
+cmpEntries(const void * a, const void * b) {
+	int res = DatumGetInt32(
+		FunctionCall2(
+			cmpDatumPtr,
+			*(Datum*)a,
+			*(Datum*)b
+		)
+	);
+
+	if ( res == 0 ) 
+		needUnique = TRUE;
+
+	return res;
+}
+
+Datum*
+extractEntriesS(GinState *ginstate, Datum value, uint32 *nentries) {
+	Datum *entries;
+
+   	entries = (Datum*)DatumGetPointer(
+							FunctionCall2(
+								&ginstate->extractValueFn,
+								value,
+								PointerGetDatum( nentries )
+							)
+			);
+
+	if ( entries == NULL )
+		*nentries = 0;
+
+	if ( *nentries > 1 ) {
+		cmpDatumPtr = &ginstate->compareFn;
+		needUnique = FALSE;
+		qsort(entries, *nentries, sizeof(Datum), cmpEntries); 
+	}
+
+	return entries;
+}
+
+
+Datum*
+extractEntriesSU(GinState *ginstate, Datum value, uint32 *nentries) {
+	Datum *entries = extractEntriesS(ginstate, value, nentries);
+
+	if ( *nentries>1 && needUnique ) {
+		Datum *ptr, *res;
+
+		ptr = res = entries;
+
+		while( ptr - entries < *nentries ) {
+			if ( compareEntries(ginstate, *ptr, *res ) != 0 ) 
+				*(++res) = *ptr++;
+			else
+				ptr++;
+		}
+
+		*nentries = res + 1 - entries;
+	}
+
+	return entries;
+}
+
+/*
+ * It's analog of PageGetTempPage(), but copies whole page
+ */
+Page
+GinPageGetCopyPage( Page page ) {
+	Size    pageSize = PageGetPageSize( page );
+	Page tmppage;
+
+	tmppage=(Page)palloc( pageSize );
+	memcpy( tmppage, page, pageSize );
+	
+	return tmppage;
+}