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| author | Igor Babaev <igor@askmonty.org> | 2019-05-27 19:08:00 -0700 |
|---|---|---|
| committer | Igor Babaev <igor@askmonty.org> | 2019-05-27 19:08:23 -0700 |
| commit | 0955462d0aafab01def9c1a5ec131eb641cb9e68 (patch) | |
| tree | f9224c83f1812b08b7977e111da9e1a34093f513 /sql/sql_const.h | |
| parent | 4584c186312a6e9b16271c5d863c76f939d4df53 (diff) | |
| download | mariadb-git-0955462d0aafab01def9c1a5ec131eb641cb9e68.tar.gz | |
MDEV-18479 Assertion `join->best_read < double(1.79769313486231570815e+308L)'
or server crashes in JOIN::fix_all_splittings_in_plan after EXPLAIN
This patch resolves the problem of overflowing when performing
calculations to estimate the cost of an evaluated query execution plan.
The overflowing in a non-debug build could cause different kind of
problems uncluding crashes of the server.
Diffstat (limited to 'sql/sql_const.h')
| -rw-r--r-- | sql/sql_const.h | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/sql/sql_const.h b/sql/sql_const.h index 96b64481936..c3b03dd7848 100644 --- a/sql/sql_const.h +++ b/sql/sql_const.h @@ -214,6 +214,14 @@ #define HEAP_TEMPTABLE_LOOKUP_COST 0.05 #define DISK_TEMPTABLE_LOOKUP_COST 1.0 + +#define COST_MAX (DBL_MAX * (1.0 - DBL_EPSILON)) + +#define COST_ADD(c,d) (COST_MAX - (d) > (c) ? (c) + (d) : COST_MAX) + +#define COST_MULT(c,f) (COST_MAX / (f) > (c) ? (c) * (f) : COST_MAX) + + #define MY_CHARSET_BIN_MB_MAXLEN 1 /** Don't pack string keys shorter than this (if PACK_KEYS=1 isn't used). */ |