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MDEV-18479 Assertion `join->best_read < double(1.79769313486231570815e+308L)'

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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.
This commit is contained in:
Igor Babaev
2019-05-27 19:08:00 -07:00
parent 4584c18631
commit 0955462d0a
5 changed files with 772 additions and 79 deletions
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8
sql/sql_const.h
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@ -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). */