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BUG#29582: huge memory consumption with union, subselect, joins:

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- Don't call mysql_select() several times for the select that enumerates
  a temporary table with the results of the UNION. Making this call for
  every subquery execution caused O(#enumerated-rows-in-the-outer-query) 
  memory allocations.
- Instead, call join->reinit() and join->exec(), and
  = disable constant table detection for such joins,  
  = provide special handling for table-less constant subqueries.


sql/sql_select.cc:
  BUG#29582: huge memory consumption with union, subselect, joins:
   - Don't mark tables as constant if JOIN::no_const_tables flag is set
sql/sql_select.h:
  BUG#29582: huge memory consumption with union, subselect, joins:
   - Don't mark tables as constant if JOIN::no_const_tables flag is set
sql/sql_union.cc:
  BUG#29582: huge memory consumption with union, subselect, joins:
  - Don't call mysql_select() several times for the select that enumerates
    a temporary table with UNION results. 
  - Instead, call join->reinit() and join->exec().
  - Provide special handling for table-less constant subqueries.
This commit is contained in:
unknown
2007-07-31 15:19:06 +04:00
parent 2679e53a73
commit 8a68e7d2dc
3 changed files with 51 additions and 18 deletions
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2
sql/sql_select.cc
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@@ -2416,7 +2416,7 @@ make_join_statistics(JOIN *join, TABLE_LIST *tables, COND *conds,
if ((table->s->system || table->file->records <= 1) && ! s->dependent &&
!(table->file->table_flags() & HA_NOT_EXACT_COUNT) &&
!table->fulltext_searched)
!table->fulltext_searched && !join->no_const_tables)
{
set_position(join,const_count++,s,(KEYUSE*) 0);
}