Postgres95 1.01 Distribution - Virgin SourcesPG95-1_01

1 files changed, 275 insertions, 0 deletions

diff --git a/src/backend/access/index/genam.c b/src/backend/access/index/genam.c
new file mode 100644
index 00000000000..3d02ba57009
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+++ b/src/backend/access/index/genam.c
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+/*-------------------------------------------------------------------------
+ *
+ * genam.c--
+ *    general index access method routines
+ *
+ * Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *    $Header: /cvsroot/pgsql/src/backend/access/index/genam.c,v 1.1.1.1 1996/07/09 06:21:11 scrappy Exp $
+ *
+ * NOTES
+ *    many of the old access method routines have been turned into
+ *    macros and moved to genam.h -cim 4/30/91
+ *
+ *-------------------------------------------------------------------------
+ */
+/*
+ * OLD COMMENTS
+ * Scans are implemented as follows:
+ *
+ * `0' represents an invalid item pointer.
+ * `-' represents an unknown item pointer.
+ * `X' represents a known item pointers.
+ * `+' represents known or invalid item pointers.
+ * `*' represents any item pointers.
+ *
+ * State is represented by a triple of these symbols in the order of
+ * previous, current, next.  Note that the case of reverse scans works
+ * identically.
+ *
+ *	State	Result
+ * (1)	+ + -	+ 0 0		(if the next item pointer is invalid)
+ * (2)		+ X -		(otherwise)
+ * (3)	* 0 0	* 0 0		(no change)
+ * (4)	+ X 0	X 0 0		(shift)
+ * (5)	* + X	+ X -		(shift, add unknown)
+ *
+ * All other states cannot occur.
+ *
+ * Note:
+ *It would be possible to cache the status of the previous and
+ *	next item pointer using the flags.
+ * ----------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/attnum.h"
+#include "access/genam.h"
+#include "access/heapam.h"
+#include "access/itup.h"
+#include "access/relscan.h"
+#include "access/sdir.h"
+#include "access/skey.h"
+
+#include "storage/bufmgr.h"
+#include "utils/elog.h"
+#include "utils/palloc.h"
+#include "utils/rel.h"
+
+#include "catalog/catname.h"
+#include "catalog/pg_attribute.h"
+#include "catalog/pg_index.h"
+#include "catalog/pg_proc.h"
+
+#include "catalog/index.h"
+
+/* ----------------------------------------------------------------
+ *	general access method routines
+ *
+ *	All indexed access methods use an identical scan structure.
+ *	We don't know how the various AMs do locking, however, so we don't
+ *	do anything about that here.
+ *
+ *	The intent is that an AM implementor will define a front-end routine
+ *	that calls this one, to fill in the scan, and then does whatever kind
+ *	of locking he wants.
+ * ----------------------------------------------------------------
+ */
+
+/* ----------------
+ *  RelationGetIndexScan -- Create and fill an IndexScanDesc.
+ *
+ *	This routine creates an index scan structure and sets its contents
+ *	up correctly. This routine calls AMrescan to set up the scan with
+ *	the passed key.
+ *
+ *	Parameters:
+ *		relation -- index relation for scan.
+ *		scanFromEnd -- if true, begin scan at one of the index's
+ *			       endpoints.
+ *		numberOfKeys -- count of scan keys (more than one won't
+ *				necessarily do anything useful, yet).
+ *		key -- the ScanKey for the starting position of the scan.
+ *
+ *	Returns:
+ *		An initialized IndexScanDesc.
+ *
+ *	Side Effects:
+ *		Bumps the ref count on the relation to keep it in the cache.
+ *	
+ * ----------------
+ */
+IndexScanDesc
+RelationGetIndexScan(Relation relation,
+		     bool scanFromEnd,
+		     uint16 numberOfKeys,
+		     ScanKey key)
+{
+    IndexScanDesc	scan;
+    
+    if (! RelationIsValid(relation))
+	elog(WARN, "RelationGetIndexScan: relation invalid");
+    
+    scan = (IndexScanDesc) palloc(sizeof(IndexScanDescData));
+    
+    scan->relation = relation;
+    scan->opaque = NULL;
+    scan->numberOfKeys = numberOfKeys;
+    
+    ItemPointerSetInvalid(&scan->previousItemData);
+    ItemPointerSetInvalid(&scan->currentItemData);
+    ItemPointerSetInvalid(&scan->nextItemData);
+    ItemPointerSetInvalid(&scan->previousMarkData);
+    ItemPointerSetInvalid(&scan->currentMarkData);
+    ItemPointerSetInvalid(&scan->nextMarkData);
+
+    if (numberOfKeys > 0) {
+	scan->keyData = (ScanKey) palloc(sizeof(ScanKeyData) * numberOfKeys);
+    } else {
+	scan->keyData = NULL;
+    }
+
+    index_rescan(scan, scanFromEnd, key);
+    
+    return (scan);
+}
+
+/* ----------------
+ *  IndexScanRestart -- Restart an index scan.
+ *
+ *	This routine isn't used by any existing access method.  It's
+ *	appropriate if relation level locks are what you want.
+ *
+ *  Returns:
+ *	None.
+ *
+ *  Side Effects:
+ *	None.
+ * ----------------
+ */
+void
+IndexScanRestart(IndexScanDesc scan,
+		 bool scanFromEnd,
+		 ScanKey key)
+{
+    if (! IndexScanIsValid(scan))
+	elog(WARN, "IndexScanRestart: invalid scan");
+    
+    ItemPointerSetInvalid(&scan->previousItemData);
+    ItemPointerSetInvalid(&scan->currentItemData);
+    ItemPointerSetInvalid(&scan->nextItemData);
+    
+    if (RelationGetNumberOfBlocks(scan->relation) == 0) 
+	scan->flags = ScanUnmarked;
+    else if (scanFromEnd)
+	scan->flags = ScanUnmarked | ScanUncheckedPrevious;
+    else
+	scan->flags = ScanUnmarked | ScanUncheckedNext;
+    
+    scan->scanFromEnd = (bool) scanFromEnd;
+    
+    if (scan->numberOfKeys > 0)
+	memmove(scan->keyData,
+		key,
+		scan->numberOfKeys * sizeof(ScanKeyData));
+}
+
+/* ----------------
+ *  IndexScanEnd -- End and index scan.
+ *
+ *	This routine is not used by any existing access method, but is
+ *	suitable for use if you don't want to do sophisticated locking.
+ *
+ *  Returns:
+ *	None.
+ *
+ *  Side Effects:
+ *	None.
+ * ----------------
+ */
+void
+IndexScanEnd(IndexScanDesc scan)
+{
+    if (! IndexScanIsValid(scan))
+	elog(WARN, "IndexScanEnd: invalid scan");
+    
+    pfree(scan);
+}
+
+/* ----------------
+ *  IndexScanMarkPosition -- Mark current position in a scan.
+ *
+ *	This routine isn't used by any existing access method, but is the
+ *	one that AM implementors should use, if they don't want to do any
+ *	special locking.  If relation-level locking is sufficient, this is
+ *	the routine for you.
+ *
+ *  Returns:
+ *	None.
+ *
+ *  Side Effects:
+ *	None.
+ * ----------------
+ */
+void
+IndexScanMarkPosition(IndexScanDesc scan)
+{
+    RetrieveIndexResult	result;
+    
+    if (scan->flags & ScanUncheckedPrevious) {
+	result = 
+	    index_getnext(scan, BackwardScanDirection);
+	
+	if (result != NULL) {
+	    scan->previousItemData = result->index_iptr;
+	} else {
+	    ItemPointerSetInvalid(&scan->previousItemData);
+	}
+	
+    } else if (scan->flags & ScanUncheckedNext) {
+	result = (RetrieveIndexResult)
+	    index_getnext(scan, ForwardScanDirection);
+	
+	if (result != NULL) {
+	    scan->nextItemData = result->index_iptr;
+	} else {
+	    ItemPointerSetInvalid(&scan->nextItemData);
+	}
+    }
+    
+    scan->previousMarkData = scan->previousItemData;
+    scan->currentMarkData = scan->currentItemData;
+    scan->nextMarkData = scan->nextItemData;
+    
+    scan->flags = 0x0;	/* XXX should have a symbolic name */
+}
+
+/* ----------------
+ *  IndexScanRestorePosition -- Restore position on a marked scan.
+ *
+ *	This routine isn't used by any existing access method, but is the
+ *	one that AM implementors should use if they don't want to do any
+ *	special locking.  If relation-level locking is sufficient, then
+ *	this is the one you want.
+ *
+ *  Returns:
+ *	None.
+ *
+ *  Side Effects:
+ *	None.
+ * ----------------
+ */
+void
+IndexScanRestorePosition(IndexScanDesc scan)
+{	
+    if (scan->flags & ScanUnmarked) 
+	elog(WARN, "IndexScanRestorePosition: no mark to restore");
+    
+    scan->previousItemData = scan->previousMarkData;
+    scan->currentItemData = scan->currentMarkData;
+    scan->nextItemData = scan->nextMarkData;
+    
+    scan->flags = 0x0;	/* XXX should have a symbolic name */
+}