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MDEV-26337: subquery with groupby and ROLLUP returns incorrect results on LEFT JOIN on INDEXED values

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Disable LATERAL DERIVED optimization for subqueries that have WITH ROLLUP.

This bug could affect queries with grouping derived tables / views / CTEs
with ROLLUP. The bug could manifest itself if the corresponding
materialized derived tables are subject to split optimization.

The current implementation of the split optimization produces rows
from the derived table in an arbitrary order. So these rows must be
accumulated in another temporary table and sorted according to the
used GROUP BY clause in order to be able to generate the additional
ROLLUP rows.

This patch prohibits to use split optimization for grouping derived
tables / views / CTEs with ROLLUP.
This commit is contained in:
Sergei Petrunia
2022-01-04 00:01:52 +03:00
parent 25f598f54f
commit c04adce8ac
3 changed files with 82 additions and 1 deletions
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5
sql/opt_split.cc
View File

@ -310,6 +310,8 @@ struct SplM_field_ext_info: public SplM_field_info
occurred also in the select list of this join
9. There are defined some keys usable for ref access of fields from C
with available statistics.
10. The select doesn't use WITH ROLLUP (This limitation can probably be
lifted)
@retval
true if the answer is positive
@ -326,7 +328,8 @@ bool JOIN::check_for_splittable_materialized()
(unit->first_select()->next_select()) || // !(3)
(derived->prohibit_cond_pushdown) || // !(4)
(derived->is_recursive_with_table()) || // !(5)
(table_count == 0 || const_tables == top_join_tab_count)) // !(6)
(table_count == 0 || const_tables == top_join_tab_count) || // !(6)
rollup.state != ROLLUP::STATE_NONE) // (10)
return false;
if (group_list) // (7.1)
{