From 174b552e711c337535481dbbb35c1b7a3caa101b Mon Sep 17 00:00:00 2001 From: Bruce Momjian Date: Tue, 13 Apr 1999 17:18:29 +0000 Subject: [PATCH] There are some bugs about backward scanning using indexes. 1. Index Scan using plural indexids never scan backward as to the order of indexids. 2. The cursor using Index scan is not usable after moving past the end. This patch solves above bugs. Moreover the change of _bt_first() would be useful to extend ORDER BY patch by Jan Wieck for all descending order cases. Hiroshi Inoue --- src/backend/access/nbtree/nbtsearch.c | 72 ++++++++++++++++++++++----- src/backend/access/nbtree/nbtutils.c | 10 +++- src/backend/executor/nodeIndexscan.c | 42 +++++++++++++--- 3 files changed, 102 insertions(+), 22 deletions(-) diff --git a/src/backend/access/nbtree/nbtsearch.c b/src/backend/access/nbtree/nbtsearch.c index 593a5453bc..1ea080abd7 100644 --- a/src/backend/access/nbtree/nbtsearch.c +++ b/src/backend/access/nbtree/nbtsearch.c @@ -7,7 +7,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtsearch.c,v 1.42 1999/03/28 20:31:58 vadim Exp $ + * $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtsearch.c,v 1.43 1999/04/13 17:18:28 momjian Exp $ * *------------------------------------------------------------------------- */ @@ -733,7 +733,8 @@ _bt_next(IndexScanDesc scan, ScanDirection dir) return res; } - } while (keysok >= so->numberOfFirstKeys); + } while (keysok >= so->numberOfFirstKeys || + (keysok == -1 && ScanDirectionIsBackward(dir))); ItemPointerSetInvalid(current); so->btso_curbuf = InvalidBuffer; @@ -775,6 +776,8 @@ _bt_first(IndexScanDesc scan, ScanDirection dir) BTScanOpaque so; ScanKeyData skdata; Size keysok; + int i; + int nKeyIndex = -1; rel = scan->relation; so = (BTScanOpaque) scan->opaque; @@ -790,11 +793,34 @@ _bt_first(IndexScanDesc scan, ScanDirection dir) { _bt_orderkeys(rel, so); - strat = _bt_getstrat(rel, 1, so->keyData[0].sk_procedure); + if (ScanDirectionIsBackward(dir)) + { + for (i=0; inumberOfKeys; i++) + { + if (so->keyData[i].sk_attno != 1) + break; + strat = _bt_getstrat(rel, so->keyData[i].sk_attno, + so->keyData[i].sk_procedure); + if (strat == BTLessStrategyNumber || + strat == BTLessEqualStrategyNumber|| + strat == BTEqualStrategyNumber) + { + nKeyIndex = i; + break; + } + } + } + else + { + strat = _bt_getstrat(rel, 1, so->keyData[0].sk_procedure); - /* NOTE: it assumes ForwardScanDirection */ - if (strat == BTLessStrategyNumber || - strat == BTLessEqualStrategyNumber) + if (strat == BTLessStrategyNumber || + strat == BTLessEqualStrategyNumber) + ; + else + nKeyIndex = 0; + } + if (nKeyIndex < 0) scan->scanFromEnd = true; } else @@ -823,8 +849,8 @@ _bt_first(IndexScanDesc scan, ScanDirection dir) return (RetrieveIndexResult) NULL; } proc = index_getprocid(rel, 1, BTORDER_PROC); - ScanKeyEntryInitialize(&skdata, so->keyData[0].sk_flags, 1, proc, - so->keyData[0].sk_argument); + ScanKeyEntryInitialize(&skdata, so->keyData[nKeyIndex].sk_flags, + 1, proc, so->keyData[nKeyIndex].sk_argument); stack = _bt_search(rel, 1, &skdata, &buf); _bt_freestack(stack); @@ -897,7 +923,7 @@ _bt_first(IndexScanDesc scan, ScanDirection dir) /* it's yet other place to add some code latter for is(not)null */ - strat = _bt_getstrat(rel, 1, so->keyData[0].sk_procedure); + strat = _bt_getstrat(rel, 1, so->keyData[nKeyIndex].sk_procedure); switch (strat) { @@ -914,9 +940,6 @@ _bt_first(IndexScanDesc scan, ScanDirection dir) result = _bt_compare(rel, itupdesc, page, 1, &skdata, offnum); } while (result <= 0); - /* if this is true, the key we just looked at is gone */ - if (result > 0) - _bt_twostep(scan, &buf, ForwardScanDirection); } break; @@ -946,6 +969,21 @@ _bt_first(IndexScanDesc scan, ScanDirection dir) ItemPointerSetInvalid(&(scan->currentItemData)); return (RetrieveIndexResult) NULL; } + else if (ScanDirectionIsBackward(dir)) + { + do + { + if (!_bt_twostep(scan, &buf, ForwardScanDirection)) + break; + + offnum = ItemPointerGetOffsetNumber(current); + page = BufferGetPage(buf); + result = _bt_compare(rel, itupdesc, page, 1, &skdata, offnum); + } while (result == 0); + + if (result < 0) + _bt_twostep(scan, &buf, BackwardScanDirection); + } break; case BTGreaterEqualStrategyNumber: @@ -1026,6 +1064,11 @@ _bt_first(IndexScanDesc scan, ScanDirection dir) so->btso_curbuf = buf; return _bt_next(scan, dir); } + else if (keysok == -1 && ScanDirectionIsBackward(dir)) + { + so->btso_curbuf = buf; + return _bt_next(scan, dir); + } else { ItemPointerSetInvalid(current); @@ -1495,6 +1538,11 @@ _bt_endpoint(IndexScanDesc scan, ScanDirection dir) so->btso_curbuf = buf; return _bt_next(scan, dir); } + else if (keysok == -1 && ScanDirectionIsBackward(dir)) + { + so->btso_curbuf = buf; + return _bt_next(scan, dir); + } else { ItemPointerSetInvalid(current); diff --git a/src/backend/access/nbtree/nbtutils.c b/src/backend/access/nbtree/nbtutils.c index 193a2f7e71..39a722bb07 100644 --- a/src/backend/access/nbtree/nbtutils.c +++ b/src/backend/access/nbtree/nbtutils.c @@ -7,7 +7,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtutils.c,v 1.25 1999/02/13 23:14:37 momjian Exp $ + * $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtutils.c,v 1.26 1999/04/13 17:18:29 momjian Exp $ * *------------------------------------------------------------------------- */ @@ -367,8 +367,14 @@ _bt_checkkeys(IndexScanDesc scan, IndexTuple tuple, Size *keysok) &isNull); /* btree doesn't support 'A is null' clauses, yet */ - if (isNull || key[0].sk_flags & SK_ISNULL) + if (key[0].sk_flags & SK_ISNULL) return false; + if (isNull) + { + if (*keysok < so->numberOfFirstKeys) + *keysok = -1; + return false; + } if (key[0].sk_flags & SK_COMMUTE) { diff --git a/src/backend/executor/nodeIndexscan.c b/src/backend/executor/nodeIndexscan.c index cdf13c5e19..16bb4f23b4 100644 --- a/src/backend/executor/nodeIndexscan.c +++ b/src/backend/executor/nodeIndexscan.c @@ -7,7 +7,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/executor/nodeIndexscan.c,v 1.33 1999/02/21 03:48:40 scrappy Exp $ + * $Header: /cvsroot/pgsql/src/backend/executor/nodeIndexscan.c,v 1.34 1999/04/13 17:18:29 momjian Exp $ * *------------------------------------------------------------------------- */ @@ -96,6 +96,8 @@ IndexNext(IndexScan *node) Buffer buffer = InvalidBuffer; int numIndices; + bool bBackward; + int indexNumber; /* ---------------- * extract necessary information from index scan node * ---------------- @@ -151,8 +153,26 @@ IndexNext(IndexScan *node) * appropriate heap tuple.. else return NULL. * ---------------- */ - while (indexstate->iss_IndexPtr < numIndices) - { + bBackward = ScanDirectionIsBackward(direction); + if (bBackward) + { + indexNumber = numIndices - indexstate->iss_IndexPtr - 1; + if (indexNumber < 0) + { + indexNumber = 0; + indexstate->iss_IndexPtr = numIndices - 1; + } + } + else + { + if ((indexNumber = indexstate->iss_IndexPtr) < 0) + { + indexNumber = 0; + indexstate->iss_IndexPtr = 0; + } + } + while (indexNumber < numIndices) + { scandesc = scanDescs[indexstate->iss_IndexPtr]; while ((result = index_getnext(scandesc, direction)) != NULL) { @@ -204,8 +224,14 @@ IndexNext(IndexScan *node) if (BufferIsValid(buffer)) ReleaseBuffer(buffer); } - if (indexstate->iss_IndexPtr < numIndices) - indexstate->iss_IndexPtr++; + if (indexNumber < numIndices) + { + indexNumber++; + if (bBackward) + indexstate->iss_IndexPtr--; + else + indexstate->iss_IndexPtr++; + } } /* ---------------- * if we get here it means the index scan failed so we @@ -294,7 +320,7 @@ ExecIndexReScan(IndexScan *node, ExprContext *exprCtxt, Plan *parent) runtimeKeyInfo = (Pointer *) indexstate->iss_RuntimeKeyInfo; indxqual = node->indxqual; numScanKeys = indexstate->iss_NumScanKeys; - indexstate->iss_IndexPtr = 0; + indexstate->iss_IndexPtr = -1; /* If this is re-scanning of PlanQual ... */ if (estate->es_evTuple != NULL && @@ -611,7 +637,7 @@ ExecInitIndexScan(IndexScan *node, EState *estate, Plan *parent) */ indexstate = makeNode(IndexScanState); indexstate->iss_NumIndices = 0; - indexstate->iss_IndexPtr = 0; + indexstate->iss_IndexPtr = -1; indexstate->iss_ScanKeys = NULL; indexstate->iss_NumScanKeys = NULL; indexstate->iss_RuntimeKeyInfo = NULL; @@ -635,7 +661,7 @@ ExecInitIndexScan(IndexScan *node, EState *estate, Plan *parent) indxid = node->indxid; indxqual = node->indxqual; numIndices = length(indxid); - indexPtr = 0; + indexPtr = -1; CXT1_printf("ExecInitIndexScan: context is %d\n", CurrentMemoryContext);