This patch introduces support for the system variable eq_range_index_dive_limit
that existed in MySQL starting from 5.6. The variable sets a limit for
index dives into equality ranges. Index dives are performed by optimizer
to estimate the number of rows in range scans. Index dives usually provide
good estimate but they are pretty expensive. To estimate the number of rows
in equality ranges statistical data on indexes can be employed. Its usage gives
not so good estimates but it's cheap. So if the number of equality dives
required by an index scan exceeds the set limit no dives for equality
ranges are performed by the optimizer for this index.
As the new system variable is introduced in a stable version the default
value for it is set to a special value meaning there is no limit for the number
of index dives performed by the optimizer.
The patch partially uses the MySQL code for WL 5957
'Statistics-based Range optimization for many ranges'.
The problem was introduced by 1859caf60b:
MDEV-10175: range optimizer calls records_in_range() for full extended keys
Make the range optimizer not call records_in_range() when it would
not give any benefit.
that patch used an incorrect way to check for full extended key. Now fixing
the check.
includes:
* remove some remnants of "Bug#14521864: MYSQL 5.1 TO 5.5 BUGS PARTITIONING"
* introduce LOCK_share, now LOCK_ha_data is strictly for engines
* rea_create_table() always creates .par file (even in "frm-only" mode)
* fix a 5.6 bug, temp file leak on dummy ALTER TABLE
sql/sql_insert.cc:
CREATE ... IF NOT EXISTS may do nothing, but
it is still not a failure. don't forget to my_ok it.
******
CREATE ... IF NOT EXISTS may do nothing, but
it is still not a failure. don't forget to my_ok it.
sql/sql_table.cc:
small cleanup
******
small cleanup
client/readline.cc:
Initialize not used variable (to kill wrong compiler warning)
mysql-test/suite/handler/aria.result:
Updated test result
mysql-test/suite/handler/handler.inc:
Changed index to ensure rows are in a fixed order
mysql-test/suite/handler/heap.result:
Updated test result
mysql-test/suite/handler/innodb.result:
Updated test result
mysql-test/suite/handler/myisam.result:
Updated test result
plugin/handler_socket/handlersocket/Makefile.am:
Use CXX flags to compile
sql/filesort.cc:
Initialize variable that may be used
sql/log.cc:
Initialize not used variable (to kill wrong compiler warning)
sql/opt_range_mrr.cc:
Fixed cast to avoid compiler warning
storage/xtradb/fil/fil0fil.c:
Added cast to avoid compiler warning
When mariadb 5.3 is compiler with VS2010, several tests would enter infinite loop in
sel_arg_range_seq_next(). The reason is compiler backend bug. This bug is not
present in either VS2008 or VS2010 SP1 RC.
Workaround is to compile this function without most aggresive optimization flag
(-Og ) using #pragma optimize ("g", {on|off}) for this version of MSVC compiler.
- Make index condition pushdown be controlled by an @@optimizer_switch flag,
not by @@engine_condition_pushdown
- Make MRR buffer size be controlled by @@mrr_buffer_size, not
by @@read_rnd_buffer_size
- Move parts of code to separate files
- Code cleanup
- Add --sorted_result to some SELECTs in tests.
