BUG#38049 "incorrect rows estimations with references from preceding table"
(from revid:sergefp@mysql.com-20090126194259-ue20il3qro529l4d).
Compared to 6.0 where EXPLAIN indicates "Using index condition", here in join_optimizer.result
we see "Using where"; it's normal; 6.0 shows the same if disabling Index Condition Pushdown.
BUG#38049 "incorrect rows estimations with references from preceding table"
(from revid:sergefp@mysql.com-20090126194259-ue20il3qro529l4d).
Compared to 6.0 where EXPLAIN indicates "Using index condition", here in join_optimizer.result
we see "Using where"; it's normal; 6.0 shows the same if disabling Index Condition Pushdown.
EXPLAIN EXTENDED warning.
Query optimizer searches for the constant tables and optimizes them away. This
means that fields of such tables are substituted for their values and on later
phases they are treated as constants. After this constant tables are removed
from the query execution plan. Nevertheless constant tables were shown in
the EXPLAIN EXTENDED warning thus producing query that might be not an
equivalent of the original query.
Now the print_join function skips all tables that were optimized away from
printing to the EXPLAIN EXTENDED warning. If all tables were optimized away it
produces the 'FROM dual' clause.
mysql-test/r/explain.result:
A test case added for the bug#30302.
mysql-test/r/func_default.result:
Adjusted test case result after fix for the bug#30302.
mysql-test/r/func_regexp.result:
Adjusted test case result after fix for the bug#30302.
mysql-test/r/func_test.result:
Adjusted test case result after fix for the bug#30302.
mysql-test/r/having.result:
Adjusted test case result after fix for the bug#30302.
mysql-test/r/select.result:
Adjusted test case result after fix for the bug#30302.
mysql-test/r/subselect.result:
Adjusted test case result after fix for the bug#30302.
mysql-test/r/subselect3.result:
Adjusted test case result after fix for the bug#30302.
mysql-test/r/type_datetime.result:
Adjusted test case result after fix for the bug#30302.
mysql-test/t/explain.test:
A test case added for the bug#30302.
sql/sql_select.cc:
Bug#30302: Tables that were optimized away are printed in the
EXPLAIN EXTENDED warning.
Now the print_join function skips all tables that were optimized away from
printing to the EXPLAIN EXTENDED warning. If all tables were optimized away it
produces the 'FROM dual' clause.
sql/table.h:
Adjusted test case result after fix for the bug#30302.
The optimized_away flag is added to the TABLE_LIST struct.
EXPLAIN EXTENDED warning.
Query optimizer searches for the constant tables and optimizes them away. This
means that fields of such tables are substituted for their values and on later
phases they are treated as constants. After this constant tables are removed
from the query execution plan. Nevertheless constant tables were shown in
the EXPLAIN EXTENDED warning thus producing query that might be not an
equivalent of the original query.
Now the print_join function skips all tables that were optimized away from
printing to the EXPLAIN EXTENDED warning. If all tables were optimized away it
produces the 'FROM dual' clause.
----------------------------------------------------------
revno: 2630.22.11
committer: Konstantin Osipov <konstantin@mysql.com>
branch nick: mysql-6.0-records
timestamp: Mon 2008-08-11 16:40:09 +0400
message:
Move read_record related functions to a new header - records.h
sql/Makefile.am:
Introduce records.h
sql/handler.h:
Forward-declare class handler (an unnecessary forward declaration
was removed from mysql_priv.h).
sql/item_subselect.cc:
Make read_record function naming more consistent.
Assign read_record function at once, no need to defer till
read_first_record invocation.
sql/mysql_priv.h:
Include records.h, previously part of structs.h
sql/records.cc:
Use records.h
sql/sql_select.h:
Update to use new declarations.
sql/structs.h:
Move declarations of READ_RECORD and related functions to records.h
----------------------------------------------------------
revno: 2630.13.6
committer: Konstantin Osipov <konstantin@mysql.com>
branch nick: mysql-6.0-3288
timestamp: Fri 2008-07-11 20:22:44 +0400
message:
WL#3288, step 1: ensure that the SQL layer always closes an open
cursor (rnd or index read) before closing a handler.
sql/handler.h:
Assert that the read is closed in handler destructor.
sql/sql_select.cc:
Remove JOIN::table which was a piece of redundancy. The problem was
that JOIN::cleanup() works only if JOIN::table is not null,
but JOIN::cleanup also assigns JOIN::table to NULL. This assignment
is apparently there for safety, from the times when we had no support for correlated
subqueries. Indeed, in case of a evaluation of a correlated subquery more than once it led
to JOIN::cleanup doing nothing, and leaving the rnd or index read open.
In do_select(), make sure we call JOIN::join_free() even in case of an
error.
sql/sql_select.h:
Remove JOIN::table, JOIN::all_tables has the same functionality.
----------------------------------------------------------
revno: 2630.13.6
committer: Konstantin Osipov <konstantin@mysql.com>
branch nick: mysql-6.0-3288
timestamp: Fri 2008-07-11 20:22:44 +0400
message:
WL#3288, step 1: ensure that the SQL layer always closes an open
cursor (rnd or index read) before closing a handler.
Temporary tables may set join->group to 0 even though there is
grouping. Also need to test if sum_func_count>0 when JOIN::exec()
decides whether to present results in a grouped manner.
sql/sql_select.cc:
Temporary tables may set join->group to 0 even though there is
grouping. Also need to test if sum_func_count>0 when JOIN::exec()
decides whether to present results in a grouped manner.
Temporary tables may set join->group to 0 even though there is
grouping. Also need to test if sum_func_count>0 when JOIN::exec()
decides whether to present results in a grouped manner.
columns without where/group
Simple SELECT with implicit grouping used to return many rows if
the query was ordered by the aggregated column in the SELECT
list. This was incorrect because queries with implicit grouping
should only return a single record.
The problem was that when JOIN:exec() decided if execution needed
to handle grouping, it was assumed that sum_func_count==0 meant
that there were no aggregate functions in the query. This
assumption was not correct in JOIN::exec() because the aggregate
functions might have been optimized away during JOIN::optimize().
The reason why queries without ordering behaved correctly was
that sum_func_count is only recalculated if the optimizer chooses
to use temporary tables (which it does in the ordered case).
Hence, non-ordered queries were correctly treated as grouped.
The fix for this bug was to remove the assumption that
sum_func_count==0 means that there is no need for grouping. This
was done by introducing variable "bool implicit_grouping" in the
JOIN object.
mysql-test/r/func_group.result:
Add test for BUG#47280
mysql-test/t/func_group.test:
Add test for BUG#47280
sql/opt_sum.cc:
Improve comment for opt_sum_query()
sql/sql_class.h:
Add comment for variables in TMP_TABLE_PARAM
sql/sql_select.cc:
Introduce and use variable implicit_grouping instead of (!group_list && sum_func_count) in places that need to test if grouping is required. Also added comments for: optimization of aggregate fields for implicitly grouped queries (JOIN::optimize) and choice of end_select method (JOIN::execute)
sql/sql_select.h:
Add variable implicit_grouping, which will be TRUE for queries that contain aggregate functions but no GROUP BY clause. Also added comment to sort_and_group variable.
columns without where/group
Simple SELECT with implicit grouping used to return many rows if
the query was ordered by the aggregated column in the SELECT
list. This was incorrect because queries with implicit grouping
should only return a single record.
The problem was that when JOIN:exec() decided if execution needed
to handle grouping, it was assumed that sum_func_count==0 meant
that there were no aggregate functions in the query. This
assumption was not correct in JOIN::exec() because the aggregate
functions might have been optimized away during JOIN::optimize().
The reason why queries without ordering behaved correctly was
that sum_func_count is only recalculated if the optimizer chooses
to use temporary tables (which it does in the ordered case).
Hence, non-ordered queries were correctly treated as grouped.
The fix for this bug was to remove the assumption that
sum_func_count==0 means that there is no need for grouping. This
was done by introducing variable "bool implicit_grouping" in the
JOIN object.
local storage for query cache).
We need more than one pointer in a thread to
represent the query cache and net->query_cache_query can not be used
any more (due to ABI compatibility issues and to different life
time of NET and THD).
This is a backport of the following patch from 6.0:
----------------------------------------------------------
revno: 2476.1157.2
committer: kostja@bodhi.(none)
timestamp: Sat 2007-06-16 13:29:24 +0400
include/mysql.h.pp:
Update the ABI (NET::query_cache_query is now unused).
include/mysql_com.h:
NET::query_cache_query is now unused.
sql/mysql_priv.h:
Update signatures of ex-functios now member functions.
sql/sql_cache.cc:
Introduce THD::query_cache_tls.
sql/sql_cache.h:
Introduce THD::query_cache_tls.
sql/sql_class.cc:
Introduce THD::query_cache_tls.
sql/sql_class.h:
Introduce THD::query_cache_tls.
sql/sql_parse.cc:
Use THD::query_cache_tls.
sql/sql_select.cc:
Use THD::query_cache_tls.
local storage for query cache).
We need more than one pointer in a thread to
represent the query cache and net->query_cache_query can not be used
any more (due to ABI compatibility issues and to different life
time of NET and THD).
This is a backport of the following patch from 6.0:
----------------------------------------------------------
revno: 2476.1157.2
committer: kostja@bodhi.(none)
timestamp: Sat 2007-06-16 13:29:24 +0400
buffering is used
FORCE INDEX FOR ORDER BY now prevents the optimizer from
using join buffering. As a result the optimizer can use
indexed access on the first table and doesn't need to
sort the complete resultset at the end of the statement.
buffering is used
FORCE INDEX FOR ORDER BY now prevents the optimizer from
using join buffering. As a result the optimizer can use
indexed access on the first table and doesn't need to
sort the complete resultset at the end of the statement.
the fix is reverted from 5.1, mysql-pe as
unnecessary(no valgrind warnings there).
sql/sql_select.cc:
the fix is reverted from 5.1, mysql-pe as
unnecessary(no valgrind warnings there).
query
The fix for bug 46749 removed the check for OUTER_REF_TABLE_BIT
and substituted it for a check on the presence of
Item_ident::depended_from.
Removing it altogether was wrong : OUTER_REF_TABLE_BIT should
still be checked in addition to depended_from (because it's not
set in all cases and doesn't contradict to the check of depended_from).
Fixed by returning the old condition back as a compliment to the
new one.
query
The fix for bug 46749 removed the check for OUTER_REF_TABLE_BIT
and substituted it for a check on the presence of
Item_ident::depended_from.
Removing it altogether was wrong : OUTER_REF_TABLE_BIT should
still be checked in addition to depended_from (because it's not
set in all cases and doesn't contradict to the check of depended_from).
Fixed by returning the old condition back as a compliment to the
new one.
mysql-test/r/innodb.result:
Fix wrong merge of result file conflicts.
mysql-test/t/bug46080-master.opt:
Fix memory limit to take into account extra storage engines in MariaDB.
mysql-test/t/innodb.test:
Add comment clarifying tricky --replace_result.
sql/sql_select.cc:
Restore fix of Bug#34374, accudentally lost during MySQL 5.1.38 merge.
support-files/build-tags:
Fix missing -R option for bzr, accidentally lost in MySQL-5.1.38 merge.
