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MDEV-19258 RIGHT JOIN hangs in MariaDB

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This patch corrects the patch for the bug 10006. The latter incorrectly
calculates the attribute TABLE_LIST::dep_tables for inner tables
of outer joins that are to be converted into inner joins.
As a result after the patch some valid join orders were not evaluated
and the optimizer could choose an execution plan that was far from
being optimal.
This commit is contained in:
Igor Babaev
2019-05-14 23:58:56 -07:00
parent aad4e5637d
commit e57bb1f76c
4 changed files with 416 additions and 5 deletions
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16
sql/sql_select.cc
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@ -14635,8 +14635,20 @@ simplify_joins(JOIN *join, List<TABLE_LIST> *join_list, COND *conds, bool top,
table->table->maybe_null= FALSE;
table->outer_join= 0;
if (!(straight_join || table->straight))
table->dep_tables= table->embedding && !table->embedding->sj_subq_pred ?
table->embedding->dep_tables : 0;
{
table->dep_tables= 0;
TABLE_LIST *embedding= table->embedding;
while (embedding)
{
if (embedding->nested_join->join_list.head()->outer_join)
{
if (!embedding->sj_subq_pred)
table->dep_tables= embedding->dep_tables;
break;
}
embedding= embedding->embedding;
}
}
if (table->on_expr)
{
/* Add ON expression to the WHERE or upper-level ON condition. */