Sergey Glukhov bed0948145 Bug#51494 crash with join, explain and 'sounds like' operator ...

The crash happens because of discrepancy between values of
conts_tables and join->const_table_map(make_join_statisctics).
Calculation of conts_tables used condition with
HA_STATS_RECORDS_IS_EXACT flag check. Calculation of
join->const_table_map does not use this flag check.
In case of MERGE table without union with index
the table does not become const table and
thus join_read_const_table() is not called
for the table. join->const_table_map supposes
this table is const and later in make_join_select
this table is used for making&calculation const
condition. As table record buffer is not populated
it leads to crash.
The fix is adding a check if an engine supports
HA_STATS_RECORDS_IS_EXACT flag before updating
join->const_table_map.

2010-03-19 10:01:02 +04:00

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