Postgres95 1.01 Distribution - Virgin SourcesPG95-1_01

1 files changed, 195 insertions, 0 deletions

diff --git a/src/backend/access/heap/hio.c b/src/backend/access/heap/hio.c
new file mode 100644
index 00000000000..457e1174a30
--- /dev/null
+++ b/src/backend/access/heap/hio.c
@@ -0,0 +1,195 @@
+/*-------------------------------------------------------------------------
+ *
+ * hio.c--
+ *    POSTGRES heap access method input/output code.
+ *
+ * Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *    $Id: hio.c,v 1.1.1.1 1996/07/09 06:21:11 scrappy Exp $
+ *
+ *-------------------------------------------------------------------------
+ */
+#include <string.h>
+
+#include "c.h"
+
+#include "access/heapam.h"
+#include "access/hio.h"
+#include "access/htup.h"
+
+#include "storage/block.h"
+#include "storage/buf.h"
+#include "storage/bufmgr.h"
+#include "storage/bufpage.h"
+#include "storage/itemid.h"
+#include "storage/itemptr.h"
+#include "storage/off.h"
+
+#include "utils/memutils.h"
+#include "utils/elog.h"
+#include "utils/rel.h"
+
+/*
+ * amputunique	- place tuple at tid
+ *   Currently on errors, calls elog.  Perhaps should return -1?
+ *   Possible errors include the addition of a tuple to the page
+ *   between the time the linep is chosen and the page is L_UP'd.
+ *
+ *   This should be coordinated with the B-tree code.
+ *   Probably needs to have an amdelunique to allow for
+ *   internal index records to be deleted and reordered as needed.
+ *   For the heap AM, this should never be needed.
+ */
+void
+RelationPutHeapTuple(Relation relation,
+		     BlockNumber blockIndex,
+		     HeapTuple tuple)
+{
+    Buffer		buffer;
+    Page		pageHeader;
+    BlockNumber		numberOfBlocks;
+    OffsetNumber	offnum;
+    unsigned int	len;
+    ItemId		itemId;
+    Item		item;
+    
+    /* ----------------
+     *	increment access statistics
+     * ----------------
+     */
+    IncrHeapAccessStat(local_RelationPutHeapTuple);
+    IncrHeapAccessStat(global_RelationPutHeapTuple);
+    
+    Assert(RelationIsValid(relation));
+    Assert(HeapTupleIsValid(tuple));
+    
+    numberOfBlocks = RelationGetNumberOfBlocks(relation);
+    Assert(blockIndex < numberOfBlocks);
+    
+    buffer = ReadBuffer(relation, blockIndex);
+#ifndef NO_BUFFERISVALID
+    if (!BufferIsValid(buffer)) {
+	elog(WARN, "RelationPutHeapTuple: no buffer for %ld in %s",
+	     blockIndex, &relation->rd_rel->relname);
+    }
+#endif
+    
+    pageHeader = (Page)BufferGetPage(buffer);
+    len = (unsigned)DOUBLEALIGN(tuple->t_len);	/* be conservative */
+    Assert((int)len <= PageGetFreeSpace(pageHeader));
+    
+    offnum = PageAddItem((Page)pageHeader, (Item)tuple,
+			 tuple->t_len, InvalidOffsetNumber, LP_USED);
+    
+    itemId = PageGetItemId((Page)pageHeader, offnum);
+    item = PageGetItem((Page)pageHeader, itemId);
+    
+    ItemPointerSet(&((HeapTuple)item)->t_ctid, blockIndex, offnum);
+    
+    WriteBuffer(buffer);
+    /* return an accurate tuple */
+    ItemPointerSet(&tuple->t_ctid, blockIndex, offnum);
+}
+
+/*
+ * The heap_insert routines "know" that a buffer page is initialized to
+ * zero when a BlockExtend operation is performed. 
+ */
+
+#define PageIsNew(page) ((page)->pd_upper == 0)
+
+/*
+ * This routine is another in the series of attempts to reduce the number
+ * of I/O's and system calls executed in the various benchmarks.  In
+ * particular, this routine is used to append data to the end of a relation
+ * file without excessive lseeks.  This code should do no more than 2 semops
+ * in the ideal case.
+ *
+ * Eventually, we should cache the number of blocks in a relation somewhere.
+ * Until that time, this code will have to do an lseek to determine the number
+ * of blocks in a relation.
+ * 
+ * This code should ideally do at most 4 semops, 1 lseek, and possibly 1 write
+ * to do an append; it's possible to eliminate 2 of the semops if we do direct
+ * buffer stuff (!); the lseek and the write can go if we get
+ * RelationGetNumberOfBlocks to be useful.
+ *
+ * NOTE: This code presumes that we have a write lock on the relation.
+ *
+ * Also note that this routine probably shouldn't have to exist, and does
+ * screw up the call graph rather badly, but we are wasting so much time and
+ * system resources being massively general that we are losing badly in our
+ * performance benchmarks.
+ */
+void
+RelationPutHeapTupleAtEnd(Relation relation, HeapTuple tuple)
+{
+    Buffer		buffer;
+    Page		pageHeader;
+    BlockNumber		lastblock;
+    OffsetNumber	offnum;
+    unsigned int	len;
+    ItemId		itemId;
+    Item		item;
+    
+    Assert(RelationIsValid(relation));
+    Assert(HeapTupleIsValid(tuple));
+    
+    /*
+     * XXX This does an lseek - VERY expensive - but at the moment it
+     * is the only way to accurately determine how many blocks are in
+     * a relation.  A good optimization would be to get this to actually
+     * work properly.
+     */
+    
+    lastblock = RelationGetNumberOfBlocks(relation);
+    
+    if (lastblock == 0)
+	{
+	    buffer = ReadBuffer(relation, lastblock);
+	    pageHeader = (Page)BufferGetPage(buffer);
+	    if (PageIsNew((PageHeader) pageHeader))
+		{
+		    buffer = ReleaseAndReadBuffer(buffer, relation, P_NEW);
+		    pageHeader = (Page)BufferGetPage(buffer);
+		    PageInit(pageHeader, BufferGetPageSize(buffer), 0);
+		}
+	}
+    else
+	buffer = ReadBuffer(relation, lastblock - 1);
+    
+    pageHeader = (Page)BufferGetPage(buffer);
+    len = (unsigned)DOUBLEALIGN(tuple->t_len);	/* be conservative */
+    
+    /*
+     * Note that this is true if the above returned a bogus page, which
+     * it will do for a completely empty relation.
+     */
+    
+    if (len > PageGetFreeSpace(pageHeader))
+	{
+	    buffer = ReleaseAndReadBuffer(buffer, relation, P_NEW);
+	    pageHeader = (Page)BufferGetPage(buffer);
+	    PageInit(pageHeader, BufferGetPageSize(buffer), 0);
+	    
+	    if (len > PageGetFreeSpace(pageHeader))
+		elog(WARN, "Tuple is too big: size %d", len);
+	}
+    
+    offnum = PageAddItem((Page)pageHeader, (Item)tuple,
+			 tuple->t_len, InvalidOffsetNumber, LP_USED);
+    
+    itemId = PageGetItemId((Page)pageHeader, offnum);
+    item = PageGetItem((Page)pageHeader, itemId);
+    
+    lastblock = BufferGetBlockNumber(buffer);
+    
+    ItemPointerSet(&((HeapTuple)item)->t_ctid, lastblock, offnum);
+    
+    /* return an accurate tuple */
+    ItemPointerSet(&tuple->t_ctid, lastblock, offnum);
+    
+    WriteBuffer(buffer);
+}