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| author | Sergey Petrunya <psergey@askmonty.org> | 2011-08-05 22:01:49 +0400 |
|---|---|---|
| committer | Sergey Petrunya <psergey@askmonty.org> | 2011-08-05 22:01:49 +0400 |
| commit | 0e19f3e36f7842583feb6bead2c2600cd620bced (patch) | |
| tree | 3b0bcc798ddfd4b469f39f285daa697f8c1ef614 /mysql-test/r/group_min_max.result | |
| parent | 332b47d718e1f25d553021819ded06961ddd4e56 (diff) | |
| download | mariadb-git-0e19f3e36f7842583feb6bead2c2600cd620bced.tar.gz | |
Backport of:
revno: 2876.47.174
revision-id: jorgen.loland@oracle.com-20110519120355-qn7eprkad9jqwu5j
parent: mayank.prasad@oracle.com-20110518143645-bdxv4udzrmqsjmhq
committer: Jorgen Loland <jorgen.loland@oracle.com>
branch nick: mysql-trunk-11765831
timestamp: Thu 2011-05-19 14:03:55 +0200
message:
BUG#11765831: 'RANGE ACCESS' MAY INCORRECTLY FILTER
AWAY QUALIFYING ROWS
The problem was that the ranges created when OR'ing two
conditions could be incorrect. Without the bugfix,
"I <> 6 OR (I <> 8 AND J = 5)" would create these ranges:
"NULL < I < 6",
"6 <= I <= 6 AND 5 <= J <= 5",
"6 < I < 8",
"8 <= I <= 8 AND 5 <= J <= 5",
"8 < I"
While the correct ranges is
"NULL < I < 6",
"6 <= I <= 6 AND 5 <= J <= 5",
"6 < I"
The problem occurs when key_or() ORs
(1) "NULL < I < 6, 6 <= I <= 6 AND 5 <= J <= 5, 6 < I" with
(2) "8 < I AND 5 <= J <= 5"
The reason for the bug is that in key_or(), SEL_ARG *tmp is
used to point to the range in (1) above that is merged with
(2) while key1 points to the root of the red-black tree of
(1). When merging (1) and (2), tmp refers to the "6 < I"
part whereas the root is the "6 <= ... AND 5 <= J <= 5" part.
key_or() decides that the tmp range needs to be split into
"6 < I < 8, 8 <= I <= 8, 8 < I", in which next_key_part of the
second range should be that of tmp. However, next_key_part is
set to key1->next_key_part ("5 <= J <= 5") instead of
tmp->next_key_part (empty). Fixing this gives the correct but
not optimal ranges:
"NULL < I < 6",
"6 <= I <= 6 AND 5 <= J <= 5",
"6 < I < 8",
"8 <= I <= 8",
"8 < I"
A second problem can be seen above: key_or() may create
adjacent ranges that could be replaced with a single range.
Fixes for this is also included in the patch so that the range
above becomes correct AND optimal:
"NULL < I < 6",
"6 <= I <= 6 AND 5 <= J <= 5",
"6 < I"
Merging adjacent ranges like this gives a slightly lower cost
estimate for the range access.
Diffstat (limited to 'mysql-test/r/group_min_max.result')
| -rw-r--r-- | mysql-test/r/group_min_max.result | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/mysql-test/r/group_min_max.result b/mysql-test/r/group_min_max.result index 7cd0011427e..6850d7c1993 100644 --- a/mysql-test/r/group_min_max.result +++ b/mysql-test/r/group_min_max.result @@ -876,10 +876,10 @@ id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 range NULL idx_t1_1 163 NULL 17 Using where; Using index for group-by explain select a1,a2,b, max(c) from t1 where (c > 'b1') or (c <= 'g1') group by a1,a2,b; id select_type table type possible_keys key key_len ref rows Extra -1 SIMPLE t1 range NULL idx_t1_1 163 NULL 17 Using where; Using index for group-by +1 SIMPLE t1 range NULL idx_t1_1 147 NULL 17 Using where; Using index for group-by explain select a1,a2,b,min(c),max(c) from t1 where (c > 'b1') or (c <= 'g1') group by a1,a2,b; id select_type table type possible_keys key key_len ref rows Extra -1 SIMPLE t1 range NULL idx_t1_1 163 NULL 17 Using where; Using index for group-by +1 SIMPLE t1 range NULL idx_t1_1 147 NULL 17 Using where; Using index for group-by explain select a1,a2,b,min(c),max(c) from t1 where (c > 'b111') and (c <= 'g112') group by a1,a2,b; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 range NULL idx_t1_1 163 NULL 17 Using where; Using index for group-by @@ -924,7 +924,7 @@ id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t2 range NULL idx_t2_1 163 NULL # Using where; Using index for group-by explain select a1,a2,b, max(c) from t2 where (c > 'b1') or (c <= 'g1') group by a1,a2,b; id select_type table type possible_keys key key_len ref rows Extra -1 SIMPLE t2 range NULL idx_t2_1 163 NULL # Using where; Using index for group-by +1 SIMPLE t2 range NULL idx_t2_1 146 NULL # Using where; Using index for group-by explain select a1,a2,b,min(c),max(c) from t2 where (c > 'b1') or (c <= 'g1') group by a1,a2,b; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t2 range NULL idx_t2_1 163 NULL # Using where; Using index for group-by |