Postgres95 1.01 Distribution - Virgin SourcesPG95-1_01

1 files changed, 320 insertions, 0 deletions

diff --git a/src/backend/access/rtree/rtget.c b/src/backend/access/rtree/rtget.c
new file mode 100644
index 00000000000..fb2e169297d
--- /dev/null
+++ b/src/backend/access/rtree/rtget.c
@@ -0,0 +1,320 @@
+/*-------------------------------------------------------------------------
+ *
+ * rtget.c--
+ *    fetch tuples from an rtree scan.
+ *
+ * Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *    $Header: /cvsroot/pgsql/src/backend/access/rtree/Attic/rtget.c,v 1.1.1.1 1996/07/09 06:21:13 scrappy Exp $
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "storage/bufmgr.h"
+#include "storage/bufpage.h"
+
+#include "utils/elog.h"
+#include "utils/palloc.h"
+#include "utils/rel.h"
+
+#include "access/heapam.h"
+#include "access/genam.h"
+#include "access/iqual.h"
+#include "access/rtree.h"
+#include "access/sdir.h"
+
+static OffsetNumber findnext(IndexScanDesc s, Page p, OffsetNumber n,
+			     ScanDirection dir);
+static RetrieveIndexResult rtscancache(IndexScanDesc s, ScanDirection dir);
+static RetrieveIndexResult rtfirst(IndexScanDesc s, ScanDirection dir);
+static RetrieveIndexResult rtnext(IndexScanDesc s, ScanDirection dir);
+static ItemPointer rtheapptr(Relation r, ItemPointer itemp);
+
+
+RetrieveIndexResult
+rtgettuple(IndexScanDesc s, ScanDirection dir)
+{
+    RetrieveIndexResult res;
+    
+    /* if we have it cached in the scan desc, just return the value */
+    if ((res = rtscancache(s, dir)) != (RetrieveIndexResult) NULL)
+	return (res);
+    
+    /* not cached, so we'll have to do some work */
+    if (ItemPointerIsValid(&(s->currentItemData))) {
+	res = rtnext(s, dir);
+    } else {
+	res = rtfirst(s, dir);
+    }
+    return (res);
+}
+
+static RetrieveIndexResult
+rtfirst(IndexScanDesc s, ScanDirection dir)
+{
+    Buffer b;
+    Page p;
+    OffsetNumber n;
+    OffsetNumber maxoff;
+    RetrieveIndexResult res;
+    RTreePageOpaque po;
+    RTreeScanOpaque so;
+    RTSTACK *stk;
+    BlockNumber blk;
+    IndexTuple it;
+    ItemPointer ip;
+    
+    b = ReadBuffer(s->relation, P_ROOT);
+    p = BufferGetPage(b);
+    po = (RTreePageOpaque) PageGetSpecialPointer(p);
+    so = (RTreeScanOpaque) s->opaque;
+    
+    for (;;) {
+	maxoff = PageGetMaxOffsetNumber(p);
+	if (ScanDirectionIsBackward(dir))
+	    n = findnext(s, p, maxoff, dir);
+	else
+	    n = findnext(s, p, FirstOffsetNumber, dir);
+	
+	while (n < FirstOffsetNumber || n > maxoff) {
+	    
+	    ReleaseBuffer(b);
+	    if (so->s_stack == (RTSTACK *) NULL)
+		return ((RetrieveIndexResult) NULL);
+	    
+	    stk = so->s_stack;
+	    b = ReadBuffer(s->relation, stk->rts_blk);
+	    p = BufferGetPage(b);
+	    po = (RTreePageOpaque) PageGetSpecialPointer(p);
+	    maxoff = PageGetMaxOffsetNumber(p);
+	    
+	    if (ScanDirectionIsBackward(dir)) {
+		n = OffsetNumberPrev(stk->rts_child);
+	    } else {
+		n = OffsetNumberNext(stk->rts_child);
+	    }
+	    so->s_stack = stk->rts_parent;
+	    pfree(stk);
+	    
+	    n = findnext(s, p, n, dir);
+	}
+	if (po->flags & F_LEAF) {
+	    ItemPointerSet(&(s->currentItemData), BufferGetBlockNumber(b), n);
+	    
+	    it = (IndexTuple) PageGetItem(p, PageGetItemId(p, n));
+	    ip = (ItemPointer) palloc(sizeof(ItemPointerData));
+	    memmove((char *) ip, (char *) &(it->t_tid),
+		    sizeof(ItemPointerData));
+	    ReleaseBuffer(b);
+	    
+	    res = FormRetrieveIndexResult(&(s->currentItemData), ip);
+	    
+	    return (res);
+	} else {
+	    stk = (RTSTACK *) palloc(sizeof(RTSTACK));
+	    stk->rts_child = n;
+	    stk->rts_blk = BufferGetBlockNumber(b);
+	    stk->rts_parent = so->s_stack;
+	    so->s_stack = stk;
+	    
+	    it = (IndexTuple) PageGetItem(p, PageGetItemId(p, n));
+	    blk = ItemPointerGetBlockNumber(&(it->t_tid));
+	    
+	    ReleaseBuffer(b);
+	    b = ReadBuffer(s->relation, blk);
+	    p = BufferGetPage(b);
+	    po = (RTreePageOpaque) PageGetSpecialPointer(p);
+	}
+    }
+}
+
+static RetrieveIndexResult
+rtnext(IndexScanDesc s, ScanDirection dir)
+{
+    Buffer b;
+    Page p;
+    OffsetNumber n;
+    OffsetNumber maxoff;
+    RetrieveIndexResult res;
+    RTreePageOpaque po;
+    RTreeScanOpaque so;
+    RTSTACK *stk;
+    BlockNumber blk;
+    IndexTuple it;
+    ItemPointer ip;
+    
+    blk = ItemPointerGetBlockNumber(&(s->currentItemData));
+    n = ItemPointerGetOffsetNumber(&(s->currentItemData));
+    
+    if (ScanDirectionIsForward(dir)) {
+	n = OffsetNumberNext(n);
+    } else {
+	n = OffsetNumberPrev(n);
+    }
+
+    b = ReadBuffer(s->relation, blk);
+    p = BufferGetPage(b);
+    po = (RTreePageOpaque) PageGetSpecialPointer(p);
+    so = (RTreeScanOpaque) s->opaque;
+    
+    for (;;) {
+	maxoff = PageGetMaxOffsetNumber(p);
+	n = findnext(s, p, n, dir);
+	
+	while (n < FirstOffsetNumber || n > maxoff) {
+	    
+	    ReleaseBuffer(b);
+	    if (so->s_stack == (RTSTACK *) NULL)
+		return ((RetrieveIndexResult) NULL);
+	    
+	    stk = so->s_stack;
+	    b = ReadBuffer(s->relation, stk->rts_blk);
+	    p = BufferGetPage(b);
+	    maxoff = PageGetMaxOffsetNumber(p);
+	    po = (RTreePageOpaque) PageGetSpecialPointer(p);
+	    
+	    if (ScanDirectionIsBackward(dir)) {
+		n = OffsetNumberPrev(stk->rts_child);
+	    } else {
+		n = OffsetNumberNext(stk->rts_child);
+	    }
+	    so->s_stack = stk->rts_parent;
+	    pfree(stk);
+	    
+	    n = findnext(s, p, n, dir);
+	}
+	if (po->flags & F_LEAF) {
+	    ItemPointerSet(&(s->currentItemData), BufferGetBlockNumber(b), n);
+	    
+	    it = (IndexTuple) PageGetItem(p, PageGetItemId(p, n));
+	    ip = (ItemPointer) palloc(sizeof(ItemPointerData));
+	    memmove((char *) ip, (char *) &(it->t_tid),
+		    sizeof(ItemPointerData));
+	    ReleaseBuffer(b);
+	    
+	    res = FormRetrieveIndexResult(&(s->currentItemData), ip);
+	    
+	    return (res);
+	} else {
+	    stk = (RTSTACK *) palloc(sizeof(RTSTACK));
+	    stk->rts_child = n;
+	    stk->rts_blk = BufferGetBlockNumber(b);
+	    stk->rts_parent = so->s_stack;
+	    so->s_stack = stk;
+	    
+	    it = (IndexTuple) PageGetItem(p, PageGetItemId(p, n));
+	    blk = ItemPointerGetBlockNumber(&(it->t_tid));
+	    
+	    ReleaseBuffer(b);
+	    b = ReadBuffer(s->relation, blk);
+	    p = BufferGetPage(b);
+	    po = (RTreePageOpaque) PageGetSpecialPointer(p);
+	    
+	    if (ScanDirectionIsBackward(dir)) {
+		n = PageGetMaxOffsetNumber(p);
+	    } else {
+		n = FirstOffsetNumber;
+	    }
+	}
+    }
+}
+
+static OffsetNumber
+findnext(IndexScanDesc s, Page p, OffsetNumber n, ScanDirection dir)
+{
+    OffsetNumber maxoff;
+    IndexTuple it;
+    RTreePageOpaque po;
+    RTreeScanOpaque so;
+    
+    maxoff = PageGetMaxOffsetNumber(p);
+    po = (RTreePageOpaque) PageGetSpecialPointer(p);
+    so = (RTreeScanOpaque) s->opaque;
+    
+    /*
+     *  If we modified the index during the scan, we may have a pointer to
+     *  a ghost tuple, before the scan.  If this is the case, back up one.
+     */
+    
+    if (so->s_flags & RTS_CURBEFORE) {
+	so->s_flags &= ~RTS_CURBEFORE;
+	n = OffsetNumberPrev(n);
+    }
+    
+    while (n >= FirstOffsetNumber && n <= maxoff) {
+	it = (IndexTuple) PageGetItem(p, PageGetItemId(p, n));
+	if (po->flags & F_LEAF) {
+	    if (index_keytest(it, 
+			      RelationGetTupleDescriptor(s->relation),
+			      s->numberOfKeys, s->keyData))
+		break;
+	} else {
+	    if (index_keytest(it, 
+			      RelationGetTupleDescriptor(s->relation),
+			      so->s_internalNKey, so->s_internalKey))
+		break;
+	}
+	
+	if (ScanDirectionIsBackward(dir)) {
+	    n = OffsetNumberPrev(n);
+	} else {
+	    n = OffsetNumberNext(n);
+	}
+    }
+    
+    return (n);
+}
+
+static RetrieveIndexResult
+rtscancache(IndexScanDesc s, ScanDirection dir)
+{
+    RetrieveIndexResult res;
+    ItemPointer ip;
+    
+    if (!(ScanDirectionIsNoMovement(dir)
+	  && ItemPointerIsValid(&(s->currentItemData)))) {
+	
+	return ((RetrieveIndexResult) NULL);
+    } 
+    
+    ip = rtheapptr(s->relation, &(s->currentItemData));
+    
+    if (ItemPointerIsValid(ip))
+	res = FormRetrieveIndexResult(&(s->currentItemData), ip);
+    else
+	res = (RetrieveIndexResult) NULL;
+    
+    return (res);
+}
+
+/*
+ *  rtheapptr returns the item pointer to the tuple in the heap relation
+ *  for which itemp is the index relation item pointer.
+ */
+static ItemPointer
+rtheapptr(Relation r, ItemPointer itemp)
+{
+    Buffer b;
+    Page p;
+    IndexTuple it;
+    ItemPointer ip;
+    OffsetNumber n;
+    
+    ip = (ItemPointer) palloc(sizeof(ItemPointerData));
+    if (ItemPointerIsValid(itemp)) {
+	b = ReadBuffer(r, ItemPointerGetBlockNumber(itemp));
+	p = BufferGetPage(b);
+	n = ItemPointerGetOffsetNumber(itemp);
+	it = (IndexTuple) PageGetItem(p, PageGetItemId(p, n));
+	memmove((char *) ip, (char *) &(it->t_tid),
+		sizeof(ItemPointerData));
+	ReleaseBuffer(b);
+    } else {
+	ItemPointerSetInvalid(ip);
+    }
+    
+    return (ip);
+}