Commit graph

9 commits

Author SHA1 Message Date
Sergey Petrunya
997445bc8e Make EXPLAIN better at displaying MRR/BKA:
- "Using MRR" is no longer shown with range access.
- Instead, both range and BKA accesses will show one of the following:
  = "Rowid-ordered scan"
  = "Key-ordered scan"
  = "Key-ordered Rowid-ordered scan"
depending on whether DS-MRR implementation will do scan keys in order, rowids in order,
or both.
- The patch also introduces a way for other storage engines/MRR implementations to
  pass information to EXPLAIN output about the properties of employed MRR scans.
2011-04-02 14:04:45 +04:00
Igor Babaev
84a0c9b2a2 Fixed LP bug #698882.
Made sure that the optimal fields are used by TABLE_REF objects
when building index access keys to joined tables.
Fixed a bug in the template function that sorts the elements of
a list using the bubble sort algorithm. The bug caused poor
performance of the function. Also added an optimization that
skips comparison with the most heavy elements that has been 
already properly placed in the list.
Made the comparison of the fields belonging to the same Item_equal
more granular: fields belonging to the same table are also ordered
according to some rules.
2011-01-15 11:14:36 -08:00
Igor Babaev
73898792da Fixed LP bug #664594 and other bugs leading to invalid execution
plans or wrong results due to the fact that JOIN_CACHE functions
ignored the possibility of interleaving materialized semijoin 
tables with tables whose records were stored in join buffers.
This fixes would become mostly unnecessary if the new code of
mwl 90 was merged into 5.3 right now.
Yet the fix the code of optimize_wo_join_buffering was needed
in any case.
2010-11-03 12:26:18 -07:00
Igor Babaev
25f5debdc7 MWL#128: Added into EXPLAIN output info about types of the used join buffers and
about the employed join algorithms.
Refactored constructors of the JOIN_CACHE* classes.
2010-10-18 13:33:05 -07:00
Igor Babaev
21b1b5f040 Fixed bug #52636.
Applied the fix for bug #47217 from the mysql-6.0 codebase.
The patch adds not null predicates generated for the left parts
of the equality predicates used for ref accesses. This is done
for such predicates both in where conditions and on conditions.
For the where conditions the not null predicates were generated
but in 5.0/5.1 they actually never were used due to some lame
merge from 4.1 to 5.0. The fix for bug #47217 made these 
predicates to be used in the condition pushed to the tables.
Yet only this patch generates not null predicates for equality
predicated from on conditions of outer joins.
This patch introduces a performance regression that can be
observed on a test case from null_key.test. The regression
will disappear after the fix for bug #57024 from mariadb-5.1
is pulled into mariadb-5.3.
The patch contains many changes in the outputs of the EXPLAIN 
commands since generated not null predicates are considered as
parts of the conditions pushed to join tables and may add
'Usingwhere' in some rows of EXPLAINs where there used
to be no such comments.
2010-09-28 12:39:33 -07:00
Sergey Petrunya
8a06a7e3a7 MWL#110: Make EXPLAIN always show materialization separately
- Add Item_in_subselect::get_identifier() that returns subquery's id
- Change select_describe() to produce output in new format
- Update test results (checked)
2010-03-29 18:04:35 +04:00
Sergey Petrunya
c2924e155e BUG#49129: Wrong result with IN-subquery with join_cache_level=6 and firstmatch=off
- The problem was that DuplicateWeedout strategy setup code wasn't aware of the 
  fact that join buffering will be used and applied optimization that doesn't work
  together with join buffering. Fixed by making DuplicateWeedout setup code to have 
  a pessimistic check about whether there is a chance that join buffering will be 
  used.
- Make JOIN_CACHE_BKA::init() correctly process Copy_field elements that denote saving
  current rowids in the join buffer.

mysql-test/r/subselect_sj2.result:
  Update test results
mysql-test/r/subselect_sj2_jcl6.result:
  Update test results
mysql-test/r/subselect_sj_jcl6.result:
  Testcase
mysql-test/t/subselect_sj2.test:
  Update test results
mysql-test/t/subselect_sj_jcl6.test:
  Testcase
sql/opt_subselect.cc:
  - The problem was that DuplicateWeedout strategy setup code wasn't aware of the 
    fact that join buffering will be used and applied optimization that doesn't work
    together with join buffering. Fixed by making DuplicateWeedout setup code to have 
    a pessimistic check about whether there is a chance that join buffering will be 
    used.
sql/sql_join_cache.cc:
  Make JOIN_CACHE_BKA::init() correctly process Copy_field elements that denote saving current rowids in the join buffer.
sql/sql_select.cc:
  Added a question note
2010-03-07 18:41:45 +03:00
Sergey Petrunya
663773aa8c Subquery backport:
- More test results updates (checked)
2010-02-17 13:47:55 +03:00
Sergey Petrunya
b83cb52e9e Backport of subquery optimizations to 5.3.
There are still test failures because of:
- Wrong query results in outer join + semi join
- EXPLAIN output differences
2010-01-17 17:51:10 +03:00