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MDEV-28871: Assert ... failed in JOIN::dbug_verify_sj_inner_tables...

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optimize_semi_joins() calls update_sj_state() to update semi-join
optimization state in the JOIN class.

greedy_search() algorithm considers different join prefixes,
and then picks one table to put into the join prefix.
Most of the semi-join optimization state is in the table's entry
in the join->positions[cur_prefix_size].

However, it also needs to call update_sj_state() to update the
semi-join optimization state in the JOIN class.

There is one exception, which is the cause of this bug: when we're
inside optimize_semi_join_nests() and are optimizing a subquery,
optimize_semi_joins() does nothing, it doesn't call update_sj_state().

greedy_search() must not do that either.
This commit is contained in:
Sergei Petrunia
2022-07-07 22:15:42 +03:00
parent 66c06735a2
commit 0e9a255ec8
5 changed files with 46 additions and 1 deletions
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3
sql/sql_select.cc
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@ -8210,7 +8210,8 @@ greedy_search(JOIN *join,
picked semi-join operation is in best_pos->...picker, but we need to
update the global state in the JOIN object, too.
*/
update_sj_state(join, best_table, idx, remaining_tables);
if (!join->emb_sjm_nest)
update_sj_state(join, best_table, idx, remaining_tables);
/* find the position of 'best_table' in 'join->best_ref' */
best_idx= idx;