- JOIN::prepare would have set JOIN::table_count to incorrect value (bad merge of MWL 106)
- optimize_keyuse() would use table-bit as table number
(the change in optimize_keyuse is also the reason for query plan changes. Not
expected to have much effect because only handles cases of no index statistics)
- st_select_lex::register_dependency_item() ignored the fact that some of the
selects on the dependency paths could have been merged to their parents (because they
were mergeable VIEWs)
- Undo the incorrect fix in Item_subselect::recalc_used_tables(): do not call
fix_after_pullout() for Item_subselect::Ref_to_outside members.
If the expression for a derived table contained a clause LIMIT 0
SELECT from such derived table incorrectly returned a non-empty set.
Fixed by ensuring JOIN::do_send_rows to be updated after the call
of st_select_lex_unit::set_limit that sets the value of
JOIN::unit->select_limit_cnt.
Due to this bug in the function generate_derived_keys_for_table some
key definitions to access materialized derived tables or materialized
views were constructed with invalid info for their key parts.
This could make the server crash when it optimized queries using
materialized derived tables or materialized views.
- The crash was because a NOT NULL table column inside the subquery was considered NULLable
because the code thought it was on the inner side of an outer join nest.
- Fixed by making correct distinction between tables inside outer join nests and inside semi-join nests.
Split status variable Rows_read to Rows_read and Rows_tmp_read so that one can see how much real data is read.
Same was done with with Handler_update and Handler_write.
Fixed bug in MEMORY tables where some variables was counted twice.
Added new internal handler call 'ha_close()' to have one place to gather statistics.
Fixed bug where thd->open_options was set to wrong value when doing admin_recreate_table()
mysql-test/r/status.result:
Updated test results and added new tests
mysql-test/r/status_user.result:
Udated test results
mysql-test/t/status.test:
Added new test for temporary table status variables
sql/ha_partition.cc:
Changed to call ha_close() instead of close()
sql/handler.cc:
Added internal_tmp_table variable for easy checking of temporary tables.
Added new internal handler call 'ha_close()' to have one place to gather statistics.
Gather statistics for internal temporary tables.
sql/handler.h:
Added handler variables internal_tmp_table, rows_tmp_read.
Split function update_index_statistics() to two.
Added ha_update_tmp_row() for faster tmp table handling with more statistics.
sql/item_sum.cc:
ha_write_row() -> ha_write_tmp_row()
sql/multi_range_read.cc:
close() -> ha_close()
sql/mysqld.cc:
New status variables: Rows_tmp_read, Handler_tmp_update and Handler_tmp_write
sql/opt_range.cc:
close() -> ha_close()
sql/sql_base.cc:
close() -> ha_close()
sql/sql_class.cc:
Added handling of rows_tmp_read
sql/sql_class.h:
Added new satistics variables.
rows_read++ -> update_rows_read() to be able to correctly count reads to internal temp tables.
Added handler::ha_update_tmp_row()
sql/sql_connect.cc:
Added comment
sql/sql_expression_cache.cc:
ha_write_row() -> ha_write_tmp_row()
sql/sql_select.cc:
close() -> ha_close()
ha_update_row() -> ha_update_tmp_row()
sql/sql_show.cc:
ha_write_row() -> ha_write_tmp_row()
sql/sql_table.cc:
Fixed bug where thd->open_options was set to wrong value when doing admin_recreate_table()
sql/sql_union.cc:
ha_write_row() -> ha_write_tmp_row()
sql/sql_update.cc:
ha_write_row() -> ha_write_tmp_row()
sql/table.cc:
close() -> ha_close()
storage/heap/ha_heap.cc:
Removed double counting of statistic variables.
close -> ha_close() to get tmp table statistics.
storage/maria/ha_maria.cc:
close -> ha_close() to get tmp table statistics.
The following were missing in the patch for mwl106:
- KEY_PART_INFO::fieldnr were not set for generated keys to access
tmp tables storing the rows of materialized derived tables/views
- TABLE_SHARE::column_bitmap_size was not set for tmp tables storing
the rows of materialized derived tables/views.
These could cause crashes or memory overwrite.
If a view/derived table is non-mergeable then the definition of the tmp table
to store the rows for it is created at the prepare stage. In this case if the
view definition uses outer joins and a view column belongs to an inner table
of one of them then the column should be considered as nullable independently
on nullability of the underlying column. If the underlying column happens to be
defined as non-nullable then the function create_tmp_field_from_item rather
than the function create_tmp_field_from_field should be employed to create
the definition of the interesting column in the tmp table.
mysql-test/r/join.result:
Test case for LP:798597
mysql-test/t/join.test:
Test case for LP:798597
sql/sql_select.cc:
In simplify_joins we reset table->maybe_null for outer join tables that can't ever be NULL.
This caused a conflict between the previously calculated items and the group_buffer against the fields
in the temporary table that are created as not null thanks to the optimization.
The fix is to correct the group by items to also be not_null so that they match the used fields and keys.
The function setup_tables should handle table_list elements for
semijoin materialized tables in a special way when executing
a prepared statement for the second time.
The patch for bugs 717577 and 724942 has missed to make adjustments for the
call item_equal->add_const(const_item, orig_field_item) in the function
check_simple_equality that builds multiple equality for a field and a constant.
As a result, when this field happens to be a view field and the corresponding
Item_field object F is wrapped in an Item_direct_view_ref object R the object
F is placed in the multiple equality instead of the object R.
A substitution of an equal item for F potentially can cause very serious
problems and in some cases can lead to crashes of the server.
- Added regression test with queries over the WORLD database.
- Discovered and fixed several bugs in the related cost calculation
functionality both in the semijoin and non-semijon subquery code.
- Added DBUG printing of the cost variables used to decide between
IN-EXISTS and MATERIALIZATION.
- move attempt to evaluate join->exec_const_cond() out of the "Extract constant part of each ON expression" loop
(it got there by mistake when merging).
RESULT CONSISTED OF MORE THAN ONE ROW
MySQL converts incorrect DATEs and DATETIMEs to '0000-00-00' on
insertion by default. This means that this sequence is possible:
CREATE TABLE t1(date_notnull DATE NOT NULL);
INSERT INTO t1 values (NULL);
SELECT * FROM t1;
0000-00-00
At the same time, ODBC drivers do not (or at least did not in the
90's) understand the DATE and DATETIME value '0000-00-00'. Thus,
to be able to query for the value 0000-00-00 it was decided in
MySQL 4.x (or maybe even before that) that for the special case
of DATE/DATETIME NOT NULL columns, the query "SELECT ... WHERE
date_notnull IS NULL" should return rows with date_notnull ==
'0000-00-00'. This is documented misbehavior that we do not want
to change.
The hack used to make MySQL return these rows is to convert
"date_notnull IS NULL" to "date_notnull = 0". This is, however,
only done if the table date_notnull belongs to is not an inner
table of an outer join. The rationale for this seems to be that
if there is no join match for the row in the outer table,
null-complemented rows would otherwise not be returned because
the null-complemented DATE value is actually NULL. On the other
hand, this means that the "return rows with 0000-00-00 when the
query asks for IS NULL"-hack is not in effect for outer joins.
In this bug, we have a LEFT JOIN that does not misbehave like
the documentation says it should. The fix is to rewrite
"date_notnull IS NULL" to "date_notnull IS NULL OR
date_notnull = 0"
if dealing with an OUTER JOIN, otherwise
"date_notnull IS NULL" to "date_notnull = 0"
as was done before.
Note:
The bug was originally reported as different result on first
and second execution of SP. The reason was that during first
execution the query was correctly rewritten to an inner join
due to a null-rejecting predicate. On second execution the
"IS NULL" -> "= 0" rewrite was done because there was no outer
join. The real problem, though, was incorrect date/datetime
IS NULL handling for OUTER JOINs.
mysql-test/r/type_datetime.result:
Add test for BUG#12561818
mysql-test/t/type_datetime.test:
Add test for BUG#12561818
sql/sql_select.cc:
Special handling of NULL for DATE/DATETIME NOT NULL columns:
In the case of outer join,
"date_notnull IS NULL"
is now rewritten to
"date_notnull IS NULL OR date_notnull = 0"
Fixed reference to not initialized memory detected by valgrind
sql/sql_select.cc:
A bit better fix for tmp-table problem:
Use only dynamic_record format for group by and distinct.
storage/maria/ma_create.c:
DYNAMIC_RECORD format doesn't pack VARCHAR fields.
This change fixes a non-fatal uninitialized memory copy.
The function generate_derived_keys did not take into account the fact
that the last element in the array of keyuses could be just a barrier
element. In some cases it could lead to a crash of the server.
Also fixed a couple of other bugs in generate_derived_keys: the inner
loop in the body of if this function did not change the cycle variables
properly.
The reason for this is that BLOCK_RECORD format is not good when there is a lot of duplicated keys as it first writes the data (to get the row position) and
then writes the key (and thus checks for duplicates).
The code that added semi-join transformations missed checking
the state of the fixed flag for the items built with the
and_items function before calls of the fix_fields method.
This could lead to an abort failure when the first argument
of and_items() happened to be NULL.
'derived_merge':
- if the flag is off then all derived tables are materialized
- if the flag is on then mergeable derived tables are merged
'derived_with_keys':
- if the flag is off then no keys are created for derived tables
- if the flag is on then for any derived table a key to access
the derived table may be created.
Now by default both flags are on.
Later the default values for the flags will be off to comply with
the current behaviour of mysql-5.1.
Uncommented previously commented out test case from parts.partition_repair_myisam
after having added an explicit requirement to materialize the derived
table used in the test case.
introduced at the latest merge 5.1->5.2->5.3.
It is basically not needed since if SQL_SELECT::pre_idx_push_select_cond
is not NULL then SQL_SELECT::original_cond would point to the same condition
as SQL_SELECT::pre_idx_push_select_cond. Otherwise SQL_SELECT::original_cond
would be equal to SQL_SELECT::cond.
