Add a testcase and backport this fix:
Bug#14338686: MYSQL IS GENERATING DIFFERENT AND SLOWER
(IN NEWER VERSIONS) EXECUTION PLAN
PROBLEM:
While checking for an index to sort for the order by clause
in this query
"SELECT datestamp FROM contractStatusHistory WHERE
contract_id = contracts.id ORDER BY datestamp asc limit 1;"
we do not calculate the number of rows to be examined correctly.
As a result we choose index 'idx_contractStatusHistory_datestamp'
defined on the 'datestamp' field, rather than choosing index
'contract_id'. And hence the lower performance.
ANALYSIS:
While checking if an index is present to give the records in
sorted order(datestamp), we consider the selectivity of the
'ref_key'(contract_id here) using 'table->quick_condition_rows'.
'ref_key' here can be an index from 'REF_ACCESS' or from 'RANGE'.
As this is a 'REF_ACCESS', 'table->quick_condition_rows' is not
set to the actual value which is 2. Instead is set to the number
of tuples present in the table indicating that every row that
is selected would be satisfying the condition present in the query.
Hence, the selectivity becomes 1 even when we choose the index
on the order by column instead of the join_condition.
But, in reality as only 2 rows satisy the condition, we need to
examine half of the entire data set to get one tuple when we
choose index on the order by column.
Had we chosen the 'REF_ACCESS' we would have examined only 2 tuples.
Hence the delay in executing the query specified.
FIX:
While calculating the selectivity of the ref_key:
For REF_ACCESS consider quick_rows[ref_key] if range
optimizer has an estimate for this key. Else consider
'rec_per_key' statistic.
For RANGE ACCESS consider 'table->quick_condition_rows'.
- Make JOIN::const_key_parts include keyparts for which
the WHERE clause has an equality in form
"t.key_part=reference_outside_this_select"
- This allows to avoid filesort'ing in some cases (and also
avoid a difficult choice between using filesort or using an index)
The problem was that the view substitute its fields (on prepare) with reverting the change after execution. After prepare on optimization exists2in convertion substituted arguments of '=' with constsnt '1', but then one of the arguments of '=' was reverted to the view field reference.This lead to incorrect WHERE condition on the second execution.
To fix the problem we replace whole '=' with '1' permannently.
MDEV-5984: EITS: Incorrect filtered% value for single-table select with range access
- Fix calculate_cond_selectivity_for_table() to work correctly with range accesses
over multi-component keys:
= First, take selectivity of all possible range scans into account. Remember which
fields were used bt the range scans.
= Then, calculate selectivity produced by sargable predicates on fields. If a
field was used in a possible range access, assume its selectivity is already
taken into account.
- Fix table_cond_selectivity(): when quick select is used, selectivity of
COND(table) is taken into account in matching_candidates_in_table(). In
table_cond_selectivity() we should not apply it for the second time.
MDEV-5971 Asymmetry between CAST(DATE'2001-00-00') to INT and TO CHAR in prepared statements
Consistently set maybe_null flag, even not-NULL temporal literal may become NULL
in the restrictive sql_mode.
This will help the following replicaition scenario:
MariaDB 10.0 master (statement replication) -> MariaDB 10.0 slave (row based replication) -> MySQL or MariaDB 5.x slave
mysql-test/r/mysqld--help.result:
Updated help text
mysql-test/suite/rpl/r/create_or_replace_mix.result:
Added more tests
mysql-test/suite/rpl/r/create_or_replace_row.result:
Added more tests
mysql-test/suite/rpl/r/create_or_replace_statement.result:
Added more tests
mysql-test/suite/rpl/t/create_or_replace.inc:
Added more tests
sql/handler.h:
Added org_options so that we can detect what come from the query and what was possible added later.
sql/sql_insert.cc:
Only write CREATE OR REPLACE if was originally specified or if we delete a conflicting table as part of create
sql/sql_parse.cc:
Remember orginal create options
sql/sql_table.cc:
Only write CREATE OR REPLACE if was originally specified or if we delete a conflicting table as part of create
sql/sys_vars.cc:
Updated help text
Backported multi_update_check_table_access() from 5.6
The code is slightly different in MariaDB, becasue we instansiate fields in merged tables earlier.
mysql-test/mysql-test-run.pl:
Fixed comment
mysql-test/r/view_grant.result:
Merged test case from 5.6
mysql-test/t/view_grant.test:
Merged test case from 5.6
sql/sql_parse.cc:
Reset orig_want_privilege as this will be rechecked later.
If not, we will have a problem in mysql_multi_update_prepare() for the call to mysql_handle_derived()
sql/sql_update.cc:
Backport multi_update_check_table_access() from 5.6
Fixed use-copy option to mysql-test-run
mysql-test/mysql-test-run.pl:
Fixed use-copy and added comment
sql/log.cc:
Make copy_up_file_and_fill() safe for disk full
mysql-test/r/create_or_replace.result:
More tests for create or replace
mysql-test/t/create_or_replace.test:
More tests for create or replace
sql/log.cc:
Don't use binlog_hton if binlog is not enabmed
sql/sql_base.cc:
We have to call restart_trans_for_tables also if tables where not locked with LOCK TABLES.
If not, we will get a crash in TokuDB
sql/sql_insert.cc:
Don't call binlog_reset_cache() if we don't have binary log open
sql/sql_table.cc:
Don't log to binary log if not open
Better test if we where using create or replace ... select
storage/tokudb/mysql-test/tokudb_mariadb/r/create_or_replace.result:
More tests for create or replace
storage/tokudb/mysql-test/tokudb_mariadb/t/create_or_replace.test:
More tests for create or replace
Copied relevant test cases and code from the MySQL 5.6 tree
Testing of my_use_symdir moved to engines.
mysql-test/r/partition_windows.result:
Updated result file
mysql-test/suite/archive/archive_no_symlink-master.opt:
Testing of symlinks with archive
mysql-test/suite/archive/archive_no_symlink.result:
Testing of symlinks with archive
mysql-test/suite/archive/archive_no_symlink.test:
Testing of symlinks with archive
mysql-test/suite/archive/archive_symlink.result:
Testing of symlinks with archive
mysql-test/suite/archive/archive_symlink.test:
Testing of symlinks with archive
sql/log_event.cc:
Updated comment
sql/partition_info.cc:
Don't test my_use_symdir here
sql/sql_parse.cc:
Updated comment
sql/sql_table.cc:
Don't test my_use_symdir here
sql/table.cc:
Added more DBUG_PRINT
storage/archive/ha_archive.cc:
Give warnings for index_file_name and if we can't use data directory
storage/myisam/ha_myisam.cc:
Give warnings if we can't use data directory or index directory
Bug #3329 Incomplete lower_case_table_names=2 implementation
The problem was that check_db_name() converted database names to lower case also in case of lower_case_table_names=2.
Fixed by removing the conversion in check_db_name for lower_case_table_names = 2 and instead converting db name to
lower case at same places as table names are converted.
Fixed bug that SHOW CREATE DATABASE FOO showed information for database 'foo'.
I also removed some checks of lower_case_table_names when it was enough to use table_alias_charset.
mysql-test/mysql-test-run.pl:
Added --use-copy argument to force mysql-test-run to copy files instead of doing symlinks. This is needed when you run
with test directory on another file system
mysql-test/r/lowercase_table.result:
Updated results
mysql-test/r/lowercase_table2.result:
Updated results
mysql-test/suite/parts/r/partition_mgm_lc2_innodb.result:
Updated results
mysql-test/suite/parts/r/partition_mgm_lc2_memory.result:
Updated results
mysql-test/suite/parts/r/partition_mgm_lc2_myisam.result:
Updated results
mysql-test/t/lowercase_table.test:
Added tests with mixed case databases
mysql-test/t/lowercase_table2.test:
Added tests with mixed case databases
sql/log.cc:
Don't check lower_case_table_names when we can use table_alias_charset
sql/sql_base.cc:
Don't check lower_case_table_names when we can use table_alias_charset
sql/sql_db.cc:
Use cmp_db_names() for checking if current database changed.
mysql_rm_db() now converts db to lower case if lower_case_table_names was used.
Changed database options cache to use table_alias_charset. This fixed a bug where SHOW CREATE DATABASE showed wrong information.
sql/sql_parse.cc:
Change also db name to lower case when file names are changed.
Don't need to story copy of database name anymore when lower_case_table_names == 2 as check_db_name() don't convert in this case.
Updated arguments to mysqld_show_create_db().
When adding table to TABLE_LIST also convert db name to lower case if needed (same way as we do with table names).
sql/sql_show.cc:
mysqld_show_create_db() now also takes original name as argument for output to user.
sql/sql_show.h:
Updated prototype for mysqld_show_create_db()
sql/sql_table.cc:
In mysql_rename_table(), do same conversions to database name as we do for the file name
- Histogram::find_bucket() should not walk off the end of the value range.
- Address review feedback in Histogram::point_selectivity(): different handling
for zero-width buckets, and explanations.
The reason was that a couple of variables that hold number of rows that was used to calculate buffers was uint and caused an overflow.
Fixed by changing variables that could hold number of rows from uint to ulong and also added a cast for this test.
include/heap.h:
Reorder to get better alignment. Changed variables that could hold number of rows from uint to ulong
mysql-test/suite/heap/heap.result:
Added test case
mysql-test/suite/heap/heap.test:
Added test case
mysql-test/suite/plugins/t/server_audit.test:
Added sleep as we want to have disconnect logged before we try a new connect
storage/heap/ha_heap.cc:
Changed variables that could hold number of rows from uint to ulong
Limit number of rows to 4G (as most of the variables that holds rows are ulong anyway)
reset records_changed when key_stat_version is changed to not cause increments for every row changed
storage/heap/ha_heap.h:
changed records_changed to ulong as this can get big
storage/heap/hp_create.c:
Changed variables that could hold number of rows from uint to ulong
Added cast (fixed the original bug)
storage/heap/hp_delete.c:
Changed variables that could hold number of rows from uint to ulong
storage/heap/hp_open.c:
Removed not needed cast
storage/heap/hp_write.c:
Changed variables that could hold number of rows from uint to ulong
support-files/compiler_warnings.supp:
Removed extra : from supression
- Fix Histogram::point_selectivity() to work in the case where the
passed value_pos=0 (or 1) and the first (or the last) bucket in the
histogram has zero value-range (i.e one value).
[Attempt #2]
- Use a new selectivity calculation formula in Histogram::point_selectivity.
The formula is different from the old one because it was developed from scratch.
it doesn't have any possible division-by-zero problems.