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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.
This commit is contained in:
Peter Geoghegan 2019-03-31 17:24:04 -07:00
parent 8fba397f0c
commit 76a39f2295
3 changed files with 30 additions and 2 deletions
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3
src/backend/access/nbtree/nbtutils.c
View File

@ -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;
}

21
src/test/regress/expected/index_including.out
View File

@ -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;

8
src/test/regress/sql/index_including.sql
View File

@ -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));