From: Tom Lane Date: Wed, 29 Jun 2011 23:46:58 +0000 (-0400) Subject: Restore correct btree preprocessing of "indexedcol IS NULL" conditions. X-Git-Tag: REL9_1_BETA3~32 X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=3b80219e96f2d2b696ed8dc395d468b38d8ef592;p=postgresql Restore correct btree preprocessing of "indexedcol IS NULL" conditions. Such a condition is unsatisfiable in combination with any other type of btree-indexable condition (since we assume btree operators are always strict). 8.3 and 8.4 had an explicit test for this, which I removed in commit 29c4ad98293e3c5cb3fcdd413a3f4904efff8762, mistakenly thinking that the case would be subsumed by the more general handling of IS (NOT) NULL added in that patch. Put it back, and improve the comments about it, and add a regression test case. Per bug #6079 from Renat Nasyrov, and analysis by Dean Rasheed. --- diff --git a/src/backend/access/nbtree/nbtutils.c b/src/backend/access/nbtree/nbtutils.c index 2e896a258f..f87eadcdec 100644 --- a/src/backend/access/nbtree/nbtutils.c +++ b/src/backend/access/nbtree/nbtutils.c @@ -325,8 +325,14 @@ _bt_preprocess_keys(IndexScanDesc scan) /* * If = has been specified, all other keys can be eliminated as - * redundant. In case of key > 2 && key == 1 we can set qual_ok - * to false and abandon further processing. + * redundant. If we have a case like key = 1 AND key > 2, we can + * set qual_ok to false and abandon further processing. + * + * We also have to deal with the case of "key IS NULL", which is + * unsatisfiable in combination with any other index condition. + * By the time we get here, that's been classified as an equality + * check, and we've rejected any combination of it with a regular + * equality condition; but not with other types of conditions. */ if (xform[BTEqualStrategyNumber - 1]) { @@ -339,6 +345,13 @@ _bt_preprocess_keys(IndexScanDesc scan) if (!chk || j == (BTEqualStrategyNumber - 1)) continue; + if (eq->sk_flags & SK_SEARCHNULL) + { + /* IS NULL is contradictory to anything else */ + so->qual_ok = false; + return; + } + if (_bt_compare_scankey_args(scan, chk, eq, chk, &test_result)) { diff --git a/src/test/regress/expected/create_index.out b/src/test/regress/expected/create_index.out index c78d9ee1e8..b23c712204 100644 --- a/src/test/regress/expected/create_index.out +++ b/src/test/regress/expected/create_index.out @@ -1279,6 +1279,18 @@ SELECT count(*) FROM onek_with_null WHERE unique1 IS NULL AND unique2 IS NOT NUL 1 (1 row) +SELECT count(*) FROM onek_with_null WHERE unique1 IS NOT NULL AND unique1 > 500; + count +------- + 499 +(1 row) + +SELECT count(*) FROM onek_with_null WHERE unique1 IS NULL AND unique1 > 500; + count +------- + 0 +(1 row) + DROP INDEX onek_nulltest; CREATE UNIQUE INDEX onek_nulltest ON onek_with_null (unique2 desc,unique1); SELECT count(*) FROM onek_with_null WHERE unique1 IS NULL; @@ -1305,6 +1317,18 @@ SELECT count(*) FROM onek_with_null WHERE unique1 IS NULL AND unique2 IS NOT NUL 1 (1 row) +SELECT count(*) FROM onek_with_null WHERE unique1 IS NOT NULL AND unique1 > 500; + count +------- + 499 +(1 row) + +SELECT count(*) FROM onek_with_null WHERE unique1 IS NULL AND unique1 > 500; + count +------- + 0 +(1 row) + DROP INDEX onek_nulltest; CREATE UNIQUE INDEX onek_nulltest ON onek_with_null (unique2 desc nulls last,unique1); SELECT count(*) FROM onek_with_null WHERE unique1 IS NULL; @@ -1331,6 +1355,18 @@ SELECT count(*) FROM onek_with_null WHERE unique1 IS NULL AND unique2 IS NOT NUL 1 (1 row) +SELECT count(*) FROM onek_with_null WHERE unique1 IS NOT NULL AND unique1 > 500; + count +------- + 499 +(1 row) + +SELECT count(*) FROM onek_with_null WHERE unique1 IS NULL AND unique1 > 500; + count +------- + 0 +(1 row) + DROP INDEX onek_nulltest; CREATE UNIQUE INDEX onek_nulltest ON onek_with_null (unique2 nulls first,unique1); SELECT count(*) FROM onek_with_null WHERE unique1 IS NULL; @@ -1357,6 +1393,18 @@ SELECT count(*) FROM onek_with_null WHERE unique1 IS NULL AND unique2 IS NOT NUL 1 (1 row) +SELECT count(*) FROM onek_with_null WHERE unique1 IS NOT NULL AND unique1 > 500; + count +------- + 499 +(1 row) + +SELECT count(*) FROM onek_with_null WHERE unique1 IS NULL AND unique1 > 500; + count +------- + 0 +(1 row) + RESET enable_seqscan; RESET enable_indexscan; RESET enable_bitmapscan; diff --git a/src/test/regress/sql/create_index.sql b/src/test/regress/sql/create_index.sql index 31b49ca227..bf27379f59 100644 --- a/src/test/regress/sql/create_index.sql +++ b/src/test/regress/sql/create_index.sql @@ -451,6 +451,8 @@ SELECT count(*) FROM onek_with_null WHERE unique1 IS NULL; SELECT count(*) FROM onek_with_null WHERE unique1 IS NULL AND unique2 IS NULL; SELECT count(*) FROM onek_with_null WHERE unique1 IS NOT NULL; SELECT count(*) FROM onek_with_null WHERE unique1 IS NULL AND unique2 IS NOT NULL; +SELECT count(*) FROM onek_with_null WHERE unique1 IS NOT NULL AND unique1 > 500; +SELECT count(*) FROM onek_with_null WHERE unique1 IS NULL AND unique1 > 500; DROP INDEX onek_nulltest; @@ -460,6 +462,8 @@ SELECT count(*) FROM onek_with_null WHERE unique1 IS NULL; SELECT count(*) FROM onek_with_null WHERE unique1 IS NULL AND unique2 IS NULL; SELECT count(*) FROM onek_with_null WHERE unique1 IS NOT NULL; SELECT count(*) FROM onek_with_null WHERE unique1 IS NULL AND unique2 IS NOT NULL; +SELECT count(*) FROM onek_with_null WHERE unique1 IS NOT NULL AND unique1 > 500; +SELECT count(*) FROM onek_with_null WHERE unique1 IS NULL AND unique1 > 500; DROP INDEX onek_nulltest; @@ -469,6 +473,8 @@ SELECT count(*) FROM onek_with_null WHERE unique1 IS NULL; SELECT count(*) FROM onek_with_null WHERE unique1 IS NULL AND unique2 IS NULL; SELECT count(*) FROM onek_with_null WHERE unique1 IS NOT NULL; SELECT count(*) FROM onek_with_null WHERE unique1 IS NULL AND unique2 IS NOT NULL; +SELECT count(*) FROM onek_with_null WHERE unique1 IS NOT NULL AND unique1 > 500; +SELECT count(*) FROM onek_with_null WHERE unique1 IS NULL AND unique1 > 500; DROP INDEX onek_nulltest; @@ -478,6 +484,8 @@ SELECT count(*) FROM onek_with_null WHERE unique1 IS NULL; SELECT count(*) FROM onek_with_null WHERE unique1 IS NULL AND unique2 IS NULL; SELECT count(*) FROM onek_with_null WHERE unique1 IS NOT NULL; SELECT count(*) FROM onek_with_null WHERE unique1 IS NULL AND unique2 IS NOT NULL; +SELECT count(*) FROM onek_with_null WHERE unique1 IS NOT NULL AND unique1 > 500; +SELECT count(*) FROM onek_with_null WHERE unique1 IS NULL AND unique1 > 500; RESET enable_seqscan; RESET enable_indexscan;