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-rw-r--r--src/backend/access/rtree/rtget.c320
1 files changed, 320 insertions, 0 deletions
diff --git a/src/backend/access/rtree/rtget.c b/src/backend/access/rtree/rtget.c
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index 00000000000..fb2e169297d
--- /dev/null
+++ b/src/backend/access/rtree/rtget.c
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+/*-------------------------------------------------------------------------
+ *
+ * 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);
+}
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