From 76a39f2295ecb040f2ea052320941e1eb9b526c0 Mon Sep 17 00:00:00 2001 From: Peter Geoghegan Date: Sun, 31 Mar 2019 17:24:04 -0700 Subject: [PATCH] Fix nbtree high key "continuescan" row compare bug. Commit 29b64d1d mishandled skipping over truncated high key attributes during row comparisons. The row comparison key matching loop would loop forever when a truncated attribute was encountered for a row compare subkey. Fix by following the example of other code in the loop: advance the current subkey, or break out of the loop when the last subkey is reached. Add test coverage for the relevant _bt_check_rowcompare() code path. The new test case is somewhat tied to nbtree implementation details, which isn't ideal, but seems unavoidable. --- src/backend/access/nbtree/nbtutils.c | 3 +++ src/test/regress/expected/index_including.out | 21 ++++++++++++++++++- src/test/regress/sql/index_including.sql | 8 ++++++- 3 files changed, 30 insertions(+), 2 deletions(-) diff --git a/src/backend/access/nbtree/nbtutils.c b/src/backend/access/nbtree/nbtutils.c index 92b8b5f134..140ac92026 100644 --- a/src/backend/access/nbtree/nbtutils.c +++ b/src/backend/access/nbtree/nbtutils.c @@ -1543,6 +1543,9 @@ _bt_check_rowcompare(ScanKey skey, IndexTuple tuple, int tupnatts, */ Assert(ScanDirectionIsForward(dir)); cmpresult = 0; + if (subkey->sk_flags & SK_ROW_END) + break; + subkey++; continue; } diff --git a/src/test/regress/expected/index_including.out b/src/test/regress/expected/index_including.out index 77ec29f2a3..2405709f40 100644 --- a/src/test/regress/expected/index_including.out +++ b/src/test/regress/expected/index_including.out @@ -126,7 +126,7 @@ DETAIL: Key (c1, c2)=(1, 2) already exists. INSERT INTO tbl SELECT 1, NULL, 3*x, box('4,4,4,4') FROM generate_series(1,10) AS x; ERROR: null value in column "c2" violates not-null constraint DETAIL: Failing row contains (1, null, 3, (4,4),(4,4)). -INSERT INTO tbl SELECT x, 2*x, NULL, NULL FROM generate_series(1,10) AS x; +INSERT INTO tbl SELECT x, 2*x, NULL, NULL FROM generate_series(1,300) AS x; explain (costs off) select * from tbl where (c1,c2,c3) < (2,5,1); QUERY PLAN @@ -144,7 +144,26 @@ select * from tbl where (c1,c2,c3) < (2,5,1); 2 | 4 | | (2 rows) +-- row comparison that compares high key at page boundary +SET enable_seqscan = off; +explain (costs off) +select * from tbl where (c1,c2,c3) < (262,1,1) limit 1; + QUERY PLAN +---------------------------------------------------- + Limit + -> Index Only Scan using covering on tbl + Index Cond: (ROW(c1, c2) <= ROW(262, 1)) + Filter: (ROW(c1, c2, c3) < ROW(262, 1, 1)) +(4 rows) + +select * from tbl where (c1,c2,c3) < (262,1,1) limit 1; + c1 | c2 | c3 | c4 +----+----+----+---- + 1 | 2 | | +(1 row) + DROP TABLE tbl; +RESET enable_seqscan; CREATE TABLE tbl (c1 int,c2 int, c3 int, c4 box, UNIQUE(c1,c2) INCLUDE(c3,c4)); SELECT indexrelid::regclass, indnatts, indnkeyatts, indisunique, indisprimary, indkey, indclass FROM pg_index WHERE indrelid = 'tbl'::regclass::oid; diff --git a/src/test/regress/sql/index_including.sql b/src/test/regress/sql/index_including.sql index c0ae71d0cb..7e517483ad 100644 --- a/src/test/regress/sql/index_including.sql +++ b/src/test/regress/sql/index_including.sql @@ -72,11 +72,17 @@ SELECT pg_get_constraintdef(oid), conname, conkey FROM pg_constraint WHERE conre -- ensure that constraint works INSERT INTO tbl SELECT 1, 2, 3*x, box('4,4,4,4') FROM generate_series(1,10) AS x; INSERT INTO tbl SELECT 1, NULL, 3*x, box('4,4,4,4') FROM generate_series(1,10) AS x; -INSERT INTO tbl SELECT x, 2*x, NULL, NULL FROM generate_series(1,10) AS x; +INSERT INTO tbl SELECT x, 2*x, NULL, NULL FROM generate_series(1,300) AS x; explain (costs off) select * from tbl where (c1,c2,c3) < (2,5,1); select * from tbl where (c1,c2,c3) < (2,5,1); +-- row comparison that compares high key at page boundary +SET enable_seqscan = off; +explain (costs off) +select * from tbl where (c1,c2,c3) < (262,1,1) limit 1; +select * from tbl where (c1,c2,c3) < (262,1,1) limit 1; DROP TABLE tbl; +RESET enable_seqscan; CREATE TABLE tbl (c1 int,c2 int, c3 int, c4 box, UNIQUE(c1,c2) INCLUDE(c3,c4));