diff options
Diffstat (limited to 'src/backend/access/nbtree/nbtutils.c')
| -rw-r--r-- | src/backend/access/nbtree/nbtutils.c | 67 |
1 files changed, 54 insertions, 13 deletions
diff --git a/src/backend/access/nbtree/nbtutils.c b/src/backend/access/nbtree/nbtutils.c index 2f596eac111..c3462a75bc7 100644 --- a/src/backend/access/nbtree/nbtutils.c +++ b/src/backend/access/nbtree/nbtutils.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtutils.c,v 1.48 2002/05/20 23:51:41 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtutils.c,v 1.49 2002/05/24 18:57:55 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -22,6 +22,9 @@ #include "executor/execdebug.h" +static int _bt_getstrategynumber(RegProcedure sk_procedure, StrategyMap map); + + /* * _bt_mkscankey * Build a scan key that contains comparison data from itup @@ -174,6 +177,11 @@ _bt_formitem(IndexTuple itup) * attribute, which can be seen to be correct by considering the above * example. * + * Furthermore, we detect the case where the index is unique and we have + * equality quals for all columns. In this case there can be at most one + * (visible) matching tuple. index_getnext uses this to avoid uselessly + * continuing the scan after finding one match. + * * The initial ordering of the keys is expected to be by attribute already * (see group_clauses_by_indexkey() in indxpath.c). The task here is to * standardize the appearance of multiple keys for the same attribute. @@ -191,8 +199,10 @@ _bt_formitem(IndexTuple itup) *---------- */ void -_bt_orderkeys(Relation relation, BTScanOpaque so) +_bt_orderkeys(IndexScanDesc scan) { + Relation relation = scan->indexRelation; + BTScanOpaque so = (BTScanOpaque) scan->opaque; ScanKeyData xform[BTMaxStrategyNumber]; bool init[BTMaxStrategyNumber]; int numberOfKeys = so->numberOfKeys; @@ -208,6 +218,7 @@ _bt_orderkeys(Relation relation, BTScanOpaque so) so->qual_ok = true; so->numberOfRequiredKeys = 0; + scan->keys_are_unique = false; if (numberOfKeys < 1) return; /* done if qual-less scan */ @@ -228,6 +239,17 @@ _bt_orderkeys(Relation relation, BTScanOpaque so) */ if (cur->sk_flags & SK_ISNULL) so->qual_ok = false; + else if (relation->rd_index->indisunique && + relation->rd_rel->relnatts == 1) + { + /* it's a unique index, do we have an equality qual? */ + map = IndexStrategyGetStrategyMap(RelationGetIndexStrategy(relation), + BTMaxStrategyNumber, + 1); + j = _bt_getstrategynumber(cur->sk_procedure, map); + if (j == (BTEqualStrategyNumber - 1)) + scan->keys_are_unique = true; + } so->numberOfRequiredKeys = 1; return; } @@ -390,17 +412,8 @@ _bt_orderkeys(Relation relation, BTScanOpaque so) MemSet(init, 0, sizeof(init)); } - /* - * OK, figure out which strategy this key corresponds to - */ - for (j = BTMaxStrategyNumber; --j >= 0;) - { - if (cur->sk_procedure == map->entry[j].sk_procedure) - break; - } - if (j < 0) - elog(ERROR, "_bt_orderkeys: unable to identify operator %u", - cur->sk_procedure); + /* figure out which strategy this key's operator corresponds to */ + j = _bt_getstrategynumber(cur->sk_procedure, map); /* have we seen one of these before? */ if (init[j]) @@ -424,6 +437,34 @@ _bt_orderkeys(Relation relation, BTScanOpaque so) } so->numberOfKeys = new_numberOfKeys; + + /* + * If unique index and we have equality keys for all columns, + * set keys_are_unique flag for higher levels. + */ + if (allEqualSoFar && relation->rd_index->indisunique && + relation->rd_rel->relnatts == new_numberOfKeys) + scan->keys_are_unique = true; +} + +/* + * Determine which btree strategy an operator procedure matches. + * + * Result is strategy number minus 1. + */ +static int +_bt_getstrategynumber(RegProcedure sk_procedure, StrategyMap map) +{ + int j; + + for (j = BTMaxStrategyNumber; --j >= 0;) + { + if (sk_procedure == map->entry[j].sk_procedure) + return j; + } + elog(ERROR, "_bt_getstrategynumber: unable to identify operator %u", + sk_procedure); + return -1; /* keep compiler quiet */ } /* |