Download | Release Notes | Changelog | Overview of 5.3

Release date: 13 Nov 2012

For the highlights of this release, see the release notes.

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  • Revision #3599 Sat 2012-11-10 00:10:06 +0200
    • Increase the version number to 5.3.10.
  • Revision #3598 Sat 2012-11-10 00:04:44 +0200
    • adjusted test result
  • Revision #3597 Fri 2012-11-09 15:27:13 +0200
    • adjust openssl_1 test as in 5.2 (no idea why this didn't merge)
  • Revision #3596 Fri 2012-11-09 13:07:32 +0200
    • MDEV-3810 fix.
    • The problem is that memory alocated by copy_andor_structure() well be freed, but if level of SELECT_LEX it will be excluded (in case of merge derived tables and view) then sl->where/having will not be updated here but still can be accessed (so it will be access to freed memory).
    • (patch by Sanja)
  • Revision #3595 [merge] Fri 2012-11-09 13:05:05 +0200
    • merge from 5.2
    • Revision #2732.57.33 Fri 2012-11-09 12:49:12 +0200
      • Disable PBXT on Windows to match all other platforms.
  • Revision #3594 [merge] Fri 2012-11-09 12:54:48 +0200
    • merge test case adjustments from 5.2
    • Revision #2732.57.32 Fri 2012-11-09 11:56:27 +0200
      • Removed the dependency on PBXT from tests information_schema_all_engines, and is_columns_is.
      • Made information_schema_all_engines stable by adding "sorted_result".
  • Revision #3593 [merge] Fri 2012-11-09 10:47:33 +0200
  • Revision #3592 [merge] Fri 2012-11-09 10:11:20 +0200
  • Revision #3591 [merge] Fri 2012-11-02 15:59:16 -0700
    • Merge.
    • Revision #3588.2.1 Thu 2012-11-01 14:54:33 -0700
      • Fixed bug MDEV-585 (LP bug #637962)
      • If, when executing a query with ORDER BY col LIMIT n, the optimizer chose an index-merge scan to access the table containing col while there existed an index defined over col then optimizer did not consider the possibility of using an alternative range scan by this index to avoid filesort. This could cause a performance degradation if the optimizer flag index_merge was set up to 'on'.
  • Revision #3590 [merge] Fri 2012-11-02 15:35:09 +0400
    • Merge: bzr ignore sql-bench/test-table-elimination
    • Revision #3588.1.1 Fri 2012-11-02 15:31:54 +0400
      • bzr ignore sql-bench/test-table-elimination
  • Revision #3589 [merge] Thu 2012-11-01 21:36:31 +0200
  • Revision #3588 Wed 2012-10-31 09:34:25 +0400
  • Revision #3587 Wed 2012-10-10 22:42:50 +0300
    • Fix of MDEV-3799.
    • Find left table in right join (which turned to left join by reordering tables in join list but phisical order of tables of SELECT left as it was).
  • Revision #3586 Wed 2012-10-10 09:21:22 +0400
    • Backport of: olav.sandstaa@oracle.com-20120516074923-vd0dhp183vqcp2ql
    • .. into MariaDB 5.3
      Fix for Bug#12667154 SAME QUERY EXEC AS WHERE SUBQ GIVES DIFFERENT
                             RESULTS ON IN() & NOT IN() COMP #3
      .  
        This bug causes a wrong result in mysql-trunk when ICP is used
        and bad performance in mysql-5.5 and mysql-trunk.
      .  
        Using the query from bug report to explain what happens and causes
        the wrong result from the query when ICP is enabled:
      .  
        1. The t3 table contains four records. The outer query will read
           these and for each of these it will execute the subquery.
      .  
        2. Before the first execution of the subquery it will be optimized. In
           this case the important is what happens to the first table t1:
           -make_join_select() will call the range optimizer which decides
            that t1 should be accessed using a range scan on the k1 index
            It creates a QUICK_RANGE_SELECT object for this.
           -As the last part of optimization the ICP code pushes the
            condition down to the storage engine for table t1 on the k1 index.
      .  
           This produces the following information in the explain for this table:
      .  
             2 DEPENDENT SUBQUERY t1 range k1 k1 5 NULL 3 Using index condition; Using filesort
      .  
           Note the use of filesort.
      .  
        3. The first execution of the subquery does (among other things) due
           to the need for sorting:
           a. Call create_sort_index() which again will call find_all_keys():
           b. find_all_keys() will read the required keys for all qualifying
              rows from the storage engine. To do this it checks if it has a
              quick-select for the table. It will use the quick-select for
              reading records. In this case it will read four records from the
              storage engine (based on the range criteria). The storage engine
              will evaluate the pushed index condition for each record.
           c. At the end of create_sort_index() there is code that cleans up a
              lot of stuff on the join tab. One of the things that is cleaned
              is the select object. The result of this is that the
              quick-select object created in make_join_select is deleted.
      .  
        4. The second execution of the subquery does the same as the first but
           the result is different:
           a. Call create_sort_index() which again will call find_all_keys()
              (same as for the first execution)
           b. find_all_keys() will read the keys from the storage engine. To
              do this it checks if it has a quick-select for the table. Now
              there is NO quick-select object(!) (since it was deleted in
              step 3c). So find_all_keys defaults to read the table using a
              table scan instead. So instead of reading the four relevant records
              in the range it reads the entire table (6 records). It then
              evaluates the table's condition (and here it goes wrong). Since
              the entire condition has been pushed down to the storage engine
              using ICP all 6 records qualify. (Note that the storage engine
              will not evaluate the pushed index condition in this case since
              it was pushed for the k1 index and now we do a table scan
              without any index being used).
              The result is that here we return six qualifying key values
              instead of four due to not evaluating the table's condition.
           c. As above.
      .  
        5. The two last execution of the subquery will also produce wrong results
           for the same reason.
      .  
        Summary: The problem occurs due to all but the first executions of the
        subquery is done as a table scan without evaluating the table's
        condition (which is pushed to the storage engine on a different
        index). This is caused by the create_sort_index() function deleting
        the quick-select object that should have been used for executing the
        subquery as a range scan.
      .  
        Note that this bug in addition to causing wrong results also can
        result in bad performance due to executing the subquery using a table
        scan instead of a range scan. This is an issue in MySQL 5.5.
      .  
        The fix for this problem is to avoid that the Quick-select-object that
        the optimizer created is deleted when create_sort_index() is doing
        clean-up of the join-tab. This will ensure that the quick-select
        object and the corresponding pushed index condition will be available
        and used by all following executions of the subquery.
      
  • Revision #3585 Fri 2012-10-05 12:26:55 +0300
    • Fix of MDEV-589.
    • The problem was in incorrect detection of merged views in tem_direct_view_ref::used_tables() .
  • Revision #3584 Mon 2012-10-01 19:04:17 -0700
    • Added the reported test case for LP bug #823237 (a duplicate of bug #823189).

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