can be specified
Currently MySQL allows one to specify what indexes to ignore during
join optimization. The scope of the current USE/FORCE/IGNORE INDEX
statement is only the FROM clause, while all other clauses are not
affected.
However, in certain cases, the optimizer
may incorrectly choose an index for sorting and/or grouping, and
produce an inefficient query plan.
This task provides the means to specify what indexes are
ignored/used for what operation in a more fine-grained manner, thus
making it possible to manually force a better plan. We do this
by extending the current IGNORE/USE/FORCE INDEX syntax to:
IGNORE/USE/FORCE INDEX [FOR {JOIN | ORDER | GROUP BY}]
so that:
- if no FOR is specified, the index hint will apply everywhere.
- if MySQL is started with the compatibility option --old_mode then
an index hint without a FOR clause works as in 5.0 (i.e, the
index will only be ignored for JOINs, but can still be used to
compute ORDER BY).
See the WL#3527 for further details.
The flag alias_name_used was not set on for the outer references
in subqueries. It resulted in replacement of any outer reference
resolved against an alias for a full field name when the frm
representation of a view with a subquery was generated.
If the subquery and the outer query referenced the same table in
their from lists this replacement effectively changed the meaning
of the view and led to wrong results for selects from this view.
Modified several functions to ensure setting the right value of
the alias_name_used flag for outer references resolved against
aliases.
When INSERT is done over a view the table being inserted into is
checked to be unique among all views tables. But if the view contains
self-joined table an error will be thrown even if all tables are used under
different aliases.
The unique_table() function now also checks tables' aliases when needed.
Fixed compile-pentium64 scripts
Fixed wrong estimate of update_with_key_prefix in sql-bench
Merge bk-internal.mysql.com:/home/bk/mysql-5.1 into mysql.com:/home/my/mysql-5.1
Fixed unsafe define of uint4korr()
Fixed that --extern works with mysql-test-run.pl
Small trivial cleanups
This also fixes a bug in counting number of rows that are updated when we have many simultanous queries
Move all connection handling and command exectuion main loop from sql_parse.cc to sql_connection.cc
Split handle_one_connection() into reusable sub functions.
Split create_new_thread() into reusable sub functions.
Added thread_scheduler; Preliminary interface code for future thread_handling code.
Use 'my_thread_id' for internal thread id's
Make thr_alarm_kill() to depend on thread_id instead of thread
Make thr_abort_locks_for_thread() depend on thread_id instead of thread
In store_globals(), set my_thread_var->id to be thd->thread_id.
Use my_thread_var->id as basis for my_thread_name()
The above changes makes the connection we have between THD and threads more soft.
Added a lot of DBUG_PRINT() and DBUG_ASSERT() functions
Fixed compiler warnings
Fixed core dumps when running with --debug
Removed setting of signal masks (was never used)
Made event code call pthread_exit() (portability fix)
Fixed that event code doesn't call DBUG_xxx functions before my_thread_init() is called.
Made handling of thread_id and thd->variables.pseudo_thread_id uniform.
Removed one common 'not freed memory' warning from mysqltest
Fixed a couple of usage of not initialized warnings (unlikely cases)
Suppress compiler warnings from bdb and (for the moment) warnings from ndb
created for sorting.
Any outer reference in a subquery was represented by an Item_field object.
If the outer select employs a temporary table all such fields should be
replaced with fields from that temporary table in order to point to the
actual data. This replacement wasn't done and that resulted in a wrong
subquery evaluation and a wrong result of the whole query.
Now any outer field is represented by two objects - Item_field placed in the
outer select and Item_outer_ref in the subquery. Item_field object is
processed as a normal field and the reference to it is saved in the
ref_pointer_array. Thus the Item_outer_ref is always references the correct
field. The original field is substituted for a reference in the
Item_field::fix_outer_field() function.
New function called fix_inner_refs() is added to fix fields referenced from
inner selects and to fix references (Item_ref objects) to these fields.
The new Item_outer_ref class is a descendant of the Item_direct_ref class.
It additionally stores a reference to the original field and designed to
behave more like a field.
- Implement --secure-file-priv=<dir> option that limits
"load_file", "LOAD DATA" and "SELECT .. INTO OUTFILE" to work
with files in specified dir.
- Use above option for mysqld in mysql-test-run.pl
The crash happens because second filling of the same I_S table happens in
case of subselect with order by. table->sort.io_cache previously allocated
in create_sort_index() is deleted during second filling
(function get_schema_tables_result). There are two places where
I_S table can be filled: JOIN::exec and create_sort_index().
To fix the bug we should check if the table was already filled
in one of these places and skip processing of the table in second.
updated.
INSERT ... ON DUPLICATE KEY UPDATE reports that a record was updated when
the duplicate key occurs even if the record wasn't actually changed
because the update values are the same as those in the record.
Now the compare_record() function is used to check whether the record was
changed and the update of a record reported only if the record differs
from the original one.
