https://mariadb.atlassian.net/browse/MDEV-28
This task implements a new clause LIMIT ROWS EXAMINED <num>
as an extention to the ANSI LIMIT clause. This extension
allows to limit the number of rows and/or keys a query
would access (read and/or write) during query execution.
The issue was that Aria allowed too long keys to be created (so that the internal buffer was not big enough to hold the whole key).
Key lengths is now limited to HA_MAX_KEY_LENGTH (1000), as for MyISAM.
Fixed failure in "_ma_apply_redo_index: Assertion `new_page_length == 0", as found by buildbot.
mysql-test/suite/maria/r/maria.result:
Updated results
mysql-test/suite/maria/r/maria3.result:
Updated results. Added test for bug fix
mysql-test/suite/maria/t/maria3.test:
Updated results. Added test for bug fix
mysql-test/suite/maria/t/optimize.test:
Updated test for new max key length
storage/maria/ha_maria.cc:
Limit key to HA_MAX_KEY_LENGTH.
storage/maria/ma_key_recover.c:
Limit used page length to max page size (this is in line with the code that writes the entry to the log).
This fixes failure in "_ma_apply_redo_index: Assertion `new_page_length == 0", as found by buildbot.
storage/maria/ma_search.c:
Extra DBUG
storage/maria/ma_write.c:
Added test to detect errors earlier.
The result of materialization of the right part of an IN subquery predicate
is placed into a temporary table. Each row of the materialized table is
distinct. A unique key over all fields of the temporary table is defined and
created. It allows to perform key look-ups into the table.
The table created for a materialized subquery can be accessed by key as
any other table. The function best_access-path search for the best access
to join a table to a given partial join. With some where conditions this
function considers a possibility of a ref_or_null access. If such access
employs the unique key on the temporary table then when estimating
the cost this access the function tries to use the array rec_per_key. Yet,
such array is not built for this unique key. This causes a crash of the server.
Rows returned by the subquery that contain nulls don't have to be placed
into temporary table, as they cannot be match any row produced by the
left part of the subquery predicate. So all fields of the temporary table
can be defined as non-nullable. In this case any ref_or_null access
to the temporary table does not make any sense and it does not make sense
to estimate such an access.
The fix makes sure that the temporary table for a materialized IN subquery
is defined with columns that are all non-nullable. The also ensures that
any row with nulls returned by the subquery is not placed into the
temporary table.
Problem was a crash in internal temporary (Maria) files when row length exceeded 65535
mysql-test/suite/maria/r/maria3.result:
Added test case
mysql-test/suite/maria/t/maria3.test:
Added test case
storage/maria/ma_open.c:
Added support for row length > 65535.
This fixes crash when using tables with longer row lengths.
Fixed README with link to source
Merged InnoDB change to XtraDB
README:
Added information of where to find MariaDB code
storage/archive/ha_archive.cc:
Removed memset() of rows, a MariaDB checksum's doesn't touch not used data.
This happend when you have more than 1024 open Aria tables during checkpoint.
mysql-test/mysql-test-run.pl:
Fixed that variable names are consistent between external and internal server.
mysql-test/suite/maria/suite.pm:
Test for aria-block-size instead of 'aria' as 'aria' is not set for embedded server.
This should be ok for aria tests, as aria is never disabled for these.
storage/maria/ma_checkpoint.c:
Fixed bug when there are more than 1024 open Aria tables during checkpoint.
timestamp: Thu 2011-12-01 15:12:10 +0100
Fix for Bug#13430436 PERFORMANCE DEGRADATION IN SYSBENCH ON INNODB DUE TO ICP
When running sysbench on InnoDB there is a performance degradation due
to index condition pushdown (ICP). Several of the queries in sysbench
have a WHERE condition that the optimizer uses for executing these
queries as range scans. The upper and lower limit of the range scan
will ensure that the WHERE condition is fulfilled. Still, the WHERE
condition is part of the queries' condition and if ICP is enabled the
condition will be pushed down to InnoDB as an index condition.
Due to the range scan's upper and lower limits ensure that the WHERE
condition is fulfilled, the pushed index condition will not filter out
any records. As a result the use of ICP for these queries results in a
performance overhead for sysbench. This overhead comes from using
resources for determining the part of the condition that can be pushed
down to InnoDB and overhead in InnoDB for executing the pushed index
condition.
With the default configuration for sysbench the range scans will use
the primary key. This is a clustered index in InnoDB. Using ICP on a
clustered index provides the lowest performance benefit since the
entire record is part of the clustered index and in InnoDB it has the
highest relative overhead for executing the pushed index condition.
The fix for removing the overhead ICP introduces when running sysbench
is to disable use of ICP when the index used by the query is a
clustered index.
When WL#6061 is implemented this change should be re-evaluated.
If the expression for a derived table of a query contained a LIMIT
clause the estimate of the number of rows in this derived table
returned by the EXPLAIN command could be badly off since the
optimizer ignored the limit number from the LIMIT clause when
getting the estimate.
The call of the method SELECT_LEX_UNIT->set_limit added in the code
of mysql_derived_optimize() will be needed also in maria-5.5 where
parameters in the LIMIT clause are supported.
configure.in:
Added testing of STRNDUP (not found on solaris)
mysql-test/include/wait_until_connected_again.inc:
Also test for error 2005 (can happen on windows)
mysql-test/include/wait_until_disconnected.inc:
Also test for error 2005 (can happen on windows)
mysql-test/suite/innodb_plugin/r/innodb_bug30423.result:
Number of rows is not stable (found difference on Solaris)
mysql-test/suite/innodb_plugin/t/innodb_bug30423.test:
Number of rows is not stable (found difference on Solaris)
plugin/auth_pam/auth_pam.c:
Use internal strndup if it doesn't exist on system (solaris)
Changed code so that it should also compile on solaris.
A table expression with a natural join or a USING clause is transformed
into an equivalent expression with equi-join ON conditions. If a reference
to a virtual column happened to occur only in these generated equi-join
conditions then it was not erroneously marked in the TABLE::vcol_set bitmap.
This could lead to wrong results for queries containing natural join
expressions or USING clauses.
The MIN/MAX optimizer code from the function opt_sum_query erroneously
did not take into account conjunctive conditions that did not depend on
any table, yet were not identified as constant items. These could be
items containing rand() or PS/SP parameters. These items are supposed
to be evaluated at the execution phase. That's why if such conditions
can be extracted from the WHERE condition the MIN/MAX optimization is
not applied as currently it is always done at the optimization phase.
(In 5.3 expensive subqueries are also evaluated only at the execution
phase. So, if a constant condition with such subquery can be extracted
from the WHERE clause the MIN/MAX optimization should not be applied
in 5.3.)
IF an IN/ALL/SOME predicate with a constant left part is transformed
into an EXISTS subquery the resulting subquery should not be considered
uncacheable if the right part of the predicate is not uncacheable.
Backported the function dbug_print_item() from 5.3. The function is used
only for debugging.
fixed several defects in the greedy optimization:
1) The greedy optimizer calculated the 'compare-cost' (CPU-cost)
for iterating over the partial plan result at each level in
the query plan as 'record_count / (double) TIME_FOR_COMPARE'
This cost was only used locally for 'best' calculation at each
level, and *not* accumulated into the total cost for the query plan.
This fix added the 'CPU-cost' of processing 'current_record_count'
records at each level to 'current_read_time' *before* it is used as
'accumulated cost' argument to recursive
best_extension_by_limited_search() calls. This ensured that the
cost of a huge join-fanout early in the QEP was correctly
reflected in the cost of the final QEP.
To get identical cost for a 'best' optimized query and a
straight_join with the same join order, the same change was also
applied to optimize_straight_join() and get_partial_join_cost()
2) Furthermore to get equal cost for 'best' optimized query and a
straight_join the new code substrcated the same '0.001' in
optimize_straight_join() as it had been already done in
best_extension_by_limited_search()
3) When best_extension_by_limited_search() aggregated the 'best' plan a
plan was 'best' by the check :
'if ((search_depth == 1) || (current_read_time < join->best_read))'
The term '(search_depth == 1' incorrectly caused a new best plan to be
collected whenever the specified 'search_depth' was reached - even if
this partial query plan was more expensive than what we had already
found.
If the sorted table belongs to a dependent subquery then the function
create_sort_index() should not clear TABLE:: select and TABLE::select
for this table after the sort of the table has been performed, because
these members are needed for the second execution of the subquery.
The patch differs from the original MySQL patch as follows:
- All test case differences have been reviewed one by one, and
care has been taken to restore the original plan so that each
test case executes the code path it was designed for.
- A bug was found and fixed in MariaDB 5.3 in
Item_allany_subselect::cleanup().
- ORDER BY is not removed because we are unsure of all effects,
and it would prevent enabling ORDER BY ... LIMIT subqueries.
- ref_pointer_array.m_size is not adjusted because we don't do
array bounds checking, and because it looks risky.
Original comment by Jorgen Loland:
-------------------------------------------------------------
WL#5953 - Optimize away useless subquery clauses
For IN/ALL/ANY/SOME/EXISTS subqueries, the following clauses are
meaningless:
* ORDER BY (since we don't support LIMIT in these subqueries)
* DISTINCT
* GROUP BY if there is no HAVING clause and no aggregate
functions
This WL detects and optimizes away these useless parts of the
query during JOIN::prepare()
Failures on SUN Solaris. Buggy compiler there required some extra initialization
for variables. Then the 02 optimization leads to bugs when values set through the
pointer are not always taken into account. Finally, the (long long) / (long)
crashes there, the explicit typeconverstion added.
Failing innodb_plunin.innodb_gis.test fixed.
per-file comments:
mysql-test/suite/innodb_plugin/t/innodb_gis.test
GIS issues fixed.
sql/gcalc_slicescan.cc
GIS issues fixed.
sql/gcalc_tools.cc
GIS issues fixed.
mysql-test/suite/maria/r/maria-recovery3.result:
Added test case for recovery bug
mysql-test/suite/maria/t/maria-recovery3.test:
Added test case for recovery bug
storage/maria/ha_maria.cc:
Don't print query twice to log
storage/maria/ma_delete.c:
More DBUG_PRINT
storage/maria/ma_key_recover.c:
Added new asserts to detect errors earlier
storage/maria/ma_recovery.c:
Update all states when moving a non-transactional file to transactional. This fixes lp:887051
The counter handler_read_key (SSV::ha_read_key_count) is incremented
incorrectly.
The mysql server maintains a per thread system_status_var (SSV)
object. This object contains among other things the counter
SSV::ha_read_key_count. The purpose of this counter is to measure the
number of requests to read a row based on a key (or the number of
index lookups).
This counter was wrongly incremented in the
ha_innobase::innobase_get_index(). The fix removes
this increment statement (for both innodb and innodb_plugin).
The various callers of the innobase_get_index() was checked to
determine if anybody must increment this counter (if they first call
innobase_get_index() and then perform an index lookup). It was found
that no caller of innobase_get_index() needs to worry about the
SSV::ha_read_key_count counter.
in EXPLAIN as select_type==MATERIALIZED.
Before, we had select_type==SUBQUERY and it was difficult to tell materialized
subqueries from uncorrelated scalar-context subqueries.
2. dialog plugin now always returns mysql->password if non-empty and the first question is of password type
3. split get_tty_password into get_tty_password_buff and strdup.
4. dialog plugin now uses get_tty_password by default
5. dialog.test
6. moved small tests of individual plugins into a dedicated suite
mysql-test/suite/maria/r/maria-autozerofill.result:
Updated test case
storage/maria/ha_maria.cc:
Write create_rename_lsn for auto_zerofilled tables.
storage/maria/ma_delete.c:
Added DBUG_ASSERT() to find errors when deleting pages.
storage/maria/ma_locking.c:
Fixed typo
storage/maria/ma_open.c:
Don't regard file as movable if create_rename_lsn is not LSN_NEEDS_NEW_STATE_LSNS
