- Unify EXPLAIN printout for <subqueryN> tables with regular tables
- Update test results for <subqueryN> tables:
s/unique_key/distinct_key/g
s/1.0/100.0/ for "filtered" column
- Make join buffering take into account that join_tabs are not a
single linear array anymore
- Remove outer join + SJ-Materialization crash (OJ+SJ the processing
is most likely still incorrect)
- Change "SUBQUERY#n" to "<subquery{n}>" in EXPLAIN output. We need to it to be
lowercase so that EXPLAIN results do not differ in case between systems with
case-sensitive and case-insensitive filesystems.
- Remove garbage comments, add better comments.
- Code cleanu.
- Make MWL#90 code require @@optimizer_switch='semijoin=on'
- Update test results with the above
- Fork subselect_mat.test - we want to check both semi-join materialization,
which now has broader scope and non-semijoin materialization.
semi-join, where the the REF buffer format was mistaken to be in
record format instead of key format. The error was that the null
byte for all fields of the record was in the front of the buffer,
and not before each field data.
was not cleaned up between PS re-executions. The reason was two-fold:
- a merge with mysql-6.0 missed select_union::cleanup() that should
have cleaned up the temp table, and
- the subclass of select_union used by materialization didn't call
the base class cleanup() method.
- Add Item_in_subselect::get_identifier() that returns subquery's id
- Change select_describe() to produce output in new format
- Update test results (checked)
mysql-test/r/union.result:
Update test results (checked, it should be "DEPENDENT SUBQUERY" as it will actually run subquery's join multiple times. There is no reason to do that but executor will still do it)
Bug#48623: Multiple subqueries are optimized incorrectly
The function setup_semijoin_dups_elimination() has a major loop that
goes through every table in the JOIN object. Usually, there is a normal
"plus one" increment in the for loop that implements this, but each semijoin
nest is treated as one entity and there is another increment that skips past
the semijoin nest to the next table in the JOIN object. However, when
combining these two increments, the next joined table is skipped, and if that
happens to be the start of another semijoin nest, the correct processing
for that nest will not be carried out.
mysql-test/r/subselect_sj.result:
Added test results for bug#48623
mysql-test/r/subselect_sj_jcl6.result:
Added test results for bug#48623
mysql-test/t/subselect_sj.test:
Added test case for bug#48623
sql/opt_subselect.cc:
Omitted the "plus one" increment in the for loop, added "plus one"
in the remaining switch case, fixed coding style issue in remaining
increment operations.
Fix two problems:
1. Let optimize_semijoin_nests() reset sj_nest->sjmat_info irrespectively
of value of optimizer_flag. We need this in case somebody has turned optimization
off between reexecutions of the same statement.
2. Do not pull out constant tables out of semi-join nests. The problem is that pullout
operation is not undoable, and if a table is constant because it is 1/0-row table it
may cease to be constant on the next execution. Note that tables that are constant
because of possible eq_ref(const) access will still be pulled out as they are
considered functionally-dependent.
Bug#48213 Materialized subselect crashes if using GEOMETRY type
The problem occurred because during semi-join a materialized table
was created which contained a GEOMETRY column, which is a specialized
BLOB column. This caused an segmentation fault because such tables will
have extra columns, and the semi-join code was not prepared for that.
The solution is to disable materialization when Blob/Geometry columns would
need to be materialized. Blob columns cannot be used for index look-up
anyway, so it does not makes sense to use materialization.
This fix implies that it is detected earlier that subquery materialization
can not be used. The result of that is that in->exist optimization may
be performed for such queries. Hence, extended query plans for such
queries had to be updated.
mysql-test/r/subselect_mat.result:
Update extended query plan for subqueries that cannot use materialization
due to Blobs.
mysql-test/r/subselect_sj.result:
Updated result file.
mysql-test/r/subselect_sj_jcl6.result:
Update result file.
mysql-test/t/subselect_sj.test:
Add test case for Bug#48213 that verifies that semi-join works when subquery select list contain Blob columns. Also verify that materialization is not
used.
sql/opt_subselect.cc:
Disable materialization for semi-join/subqueries when the subquery select list
contain Blob columns.
