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Remove support of backward scan in GiST. Per discussion

Browse Source 
http://archives.postgresql.org/pgsql-hackers/2008-10/msg00857.php
This commit is contained in:
Teodor Sigaev
2008-10-20 16:35:14 +00:00
parent a6ebb1f2f4
commit 3afffbc902
1 changed files with 15 additions and 25 deletions
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34
src/backend/access/gist/gistget.c
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@ -8,7 +8,7 @@
* Portions Copyright (c) 1994, Regents of the University of California * Portions Copyright (c) 1994, Regents of the University of California
* *
* IDENTIFICATION * IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/access/gist/gistget.c,v 1.77 2008/10/20 13:39:44 teodor Exp $ * $PostgreSQL: pgsql/src/backend/access/gist/gistget.c,v 1.78 2008/10/20 16:35:14 teodor Exp $
* *
*------------------------------------------------------------------------- *-------------------------------------------------------------------------
*/ */
@ -23,9 +23,8 @@
#include "utils/memutils.h" #include "utils/memutils.h"
static OffsetNumber gistfindnext(IndexScanDesc scan, OffsetNumber n, static OffsetNumber gistfindnext(IndexScanDesc scan, OffsetNumber n);
ScanDirection dir); static int64 gistnext(IndexScanDesc scan, TIDBitmap *tbm);
static int64 gistnext(IndexScanDesc scan, ScanDirection dir, TIDBitmap *tbm);
static bool gistindex_keytest(IndexTuple tuple, IndexScanDesc scan, static bool gistindex_keytest(IndexTuple tuple, IndexScanDesc scan,
OffsetNumber offset); OffsetNumber offset);
@ -80,6 +79,9 @@ gistgettuple(PG_FUNCTION_ARGS)
so = (GISTScanOpaque) scan->opaque; so = (GISTScanOpaque) scan->opaque;
if (dir != ForwardScanDirection)
elog(ERROR, "GiST doesn't support other scan directions than forward");
/* /*
* If we have produced an index tuple in the past and the executor has * If we have produced an index tuple in the past and the executor has
* informed us we need to mark it as "killed", do so now. * informed us we need to mark it as "killed", do so now.
@ -90,7 +92,7 @@ gistgettuple(PG_FUNCTION_ARGS)
/* /*
* Get the next tuple that matches the search key. * Get the next tuple that matches the search key.
*/ */
res = (gistnext(scan, dir, NULL) > 0); res = (gistnext(scan, NULL) > 0);
PG_RETURN_BOOL(res); PG_RETURN_BOOL(res);
} }
@ -102,7 +104,7 @@ gistgetbitmap(PG_FUNCTION_ARGS)
TIDBitmap *tbm = (TIDBitmap *) PG_GETARG_POINTER(1); TIDBitmap *tbm = (TIDBitmap *) PG_GETARG_POINTER(1);
int64 ntids; int64 ntids;
ntids = gistnext(scan, ForwardScanDirection, tbm); ntids = gistnext(scan, tbm);
PG_RETURN_INT64(ntids); PG_RETURN_INT64(ntids);
} }
@ -122,7 +124,7 @@ gistgetbitmap(PG_FUNCTION_ARGS)
* non-killed tuple that matches the search key. * non-killed tuple that matches the search key.
*/ */
static int64 static int64
gistnext(IndexScanDesc scan, ScanDirection dir, TIDBitmap *tbm) gistnext(IndexScanDesc scan, TIDBitmap *tbm)
{ {
Page p; Page p;
OffsetNumber n; OffsetNumber n;
@ -169,9 +171,6 @@ gistnext(IndexScanDesc scan, ScanDirection dir, TIDBitmap *tbm)
if ( so->curPageData < so->nPageData ) if ( so->curPageData < so->nPageData )
{ {
/*
* pageData is already ordered for scan's direction
*/
scan->xs_ctup.t_self = so->pageData[ so->curPageData ].iptr; scan->xs_ctup.t_self = so->pageData[ so->curPageData ].iptr;
scan->xs_recheck = so->pageData[ so->curPageData ].recheck; scan->xs_recheck = so->pageData[ so->curPageData ].recheck;
so->curPageData ++; so->curPageData ++;
@ -252,9 +251,6 @@ gistnext(IndexScanDesc scan, ScanDirection dir, TIDBitmap *tbm)
continue; continue;
} }
if (ScanDirectionIsBackward(dir))
n = PageGetMaxOffsetNumber(p);
else
n = FirstOffsetNumber; n = FirstOffsetNumber;
/* wonderful, we can look at page */ /* wonderful, we can look at page */
@ -262,7 +258,7 @@ gistnext(IndexScanDesc scan, ScanDirection dir, TIDBitmap *tbm)
for (;;) for (;;)
{ {
n = gistfindnext(scan, n, dir); n = gistfindnext(scan, n);
if (!OffsetNumberIsValid(n)) if (!OffsetNumberIsValid(n))
{ {
@ -275,7 +271,7 @@ gistnext(IndexScanDesc scan, ScanDirection dir, TIDBitmap *tbm)
if ( !tbm && so->nPageData > 0 ) if ( !tbm && so->nPageData > 0 )
{ {
LockBuffer(so->curbuf, GIST_UNLOCK); LockBuffer(so->curbuf, GIST_UNLOCK);
return gistnext(scan, dir, NULL); return gistnext(scan, NULL);
} }
/* /*
@ -346,9 +342,6 @@ gistnext(IndexScanDesc scan, ScanDirection dir, TIDBitmap *tbm)
so->stack->next = stk; so->stack->next = stk;
} }
if (ScanDirectionIsBackward(dir))
n = OffsetNumberPrev(n);
else
n = OffsetNumberNext(n); n = OffsetNumberNext(n);
} }
} }
@ -475,7 +468,7 @@ gistindex_keytest(IndexTuple tuple,
* Page should be locked.... * Page should be locked....
*/ */
static OffsetNumber static OffsetNumber
gistfindnext(IndexScanDesc scan, OffsetNumber n, ScanDirection dir) gistfindnext(IndexScanDesc scan, OffsetNumber n)
{ {
OffsetNumber maxoff; OffsetNumber maxoff;
IndexTuple it; IndexTuple it;
@ -500,9 +493,6 @@ gistfindnext(IndexScanDesc scan, OffsetNumber n, ScanDirection dir)
if (gistindex_keytest(it, scan, n)) if (gistindex_keytest(it, scan, n))
break; break;
if (ScanDirectionIsBackward(dir))
n = OffsetNumberPrev(n);
else
n = OffsetNumberNext(n); n = OffsetNumberNext(n);
} }