EXPLAIN EXTENDED for an UPDATE/DELETE/INSERT/REPLACE statement did not
produce the warning containing the text representation of the query
obtained after the optimization phase. Such warning was produced for
SELECT statements, but not for DML statements.
The patch fixes this defect of EXPLAIN EXTENDED for DML statements.
This patch allowed transformation of EXISTS subqueries into equivalent
IN predicands at the top level of WHERE conditions for multi-table UPDATE
and DELETE statements. There was no reason to prohibit the transformation
for such statements. The transformation provides more opportunities of
using semi-join optimizations.
Approved by Oleksandr Byelkin <sanja@mariadb.com>
Tests with checking metadata or that cannot be run with
the view-protocol are excluded from --view-protocol.
For tests that do not allow the use of an additional connection,
the util connection is disabled with "--disable_service_connection".
Also cases with bugs for --view-protocol are disabled.
Cause: a copy of the joined TABLE_LIST is created during multi_update::prepare
and TABLE::pos_in_table_list of the tables are set to point to the new
TABLE_LIST object. This prevents some optimization steps to perform correctly.
Solution: do not update pos_in_table_list during multi_update::prepare
Uninitialized ref_pointer_array[] because setup_fields() got empty
fields list. mysql_multi_update() for some reason does that by
substituting the fields list with empty total_list for the
mysql_select() call (looks like wrong merge since total_list is not
used anywhere else and is always empty). The fix would be to return
back the original fields list. But this fails update_use_source.test
case:
--error ER_BAD_FIELD_ERROR
update v1 set t1c1=2 order by 1;
Actually not failing the above seems to be ok.
The other fix would be to keep resolve_in_select_list false (and that
keeps outer context from being resolved in
Item_ref::fix_fields()). This fix is more consistent with how SELECT
behaves:
--error ER_SUBQUERY_NO_1_ROW
select a from t1 where a= (select 2 from t1 having (a = 3));
So this patch implements this fix.
Before this patch mergeable derived tables / view used in a multi-table
update / delete were merged before the preparation stage.
When the merge of a derived table / view is performed the on expression
attached to it is fixed and ANDed with the where condition of the select S
containing this derived table / view. It happens after the specification of
the derived table / view has been merged into S. If the ON expression refers
to a non existing field an error is reported and some other mergeable derived
tables / views remain unmerged. It's not a problem if the multi-table
update / delete statement is standalone. Yet if it is used in a stored
procedure the select with incompletely merged derived tables / views may
cause a problem for the second call of the procedure. This does not happen
for select queries using derived tables / views, because in this case their
specifications are merged after the preparation stage at which all ON
expressions are fixed.
This patch makes sure that merging of the derived tables / views used in a
multi-table update / delete statement is performed after the preparation
stage.
Approved by Oleksandr Byelkin <sanja@mariadb.com>
Cause
Join tmp table inserts null row because of OUTER JOIN, that's
expected. Since `multi_update::prepare2()` converted
`Item_temptable_rowid` into `Item_field` (28dbdf3)
`multi_update::send_data()` accesses join tmp record directly and
treats it as a normal row ignoring null status of ref field. NULL ref
field is then treated as normal in `multi_update::do_updates()` which
tries to position updated table by reference 0.
Note that reference 0 may be valid reference and the first row of
table can be wrongly updated (see multi_update.test).
Fix
Do not add row into multi-update tmp table in case of null ref
field. Join tmp table does not have null_row status at this time (as
well as `STATUS_NULL_ROW`) and cannot be skipped by these properties
(see first comment in multi_update::send_data()). But it has all null
fields (including the ref field).
preserve positions if the multi-update join is using tmp table:
* store positions in the tmp table if needed
JOIN::add_fields_for_current_rowid()
* take positions from the tmp table, not from file->position():
multi_update::prepare2()
