Analysis:
When a subquery that needs a temp table is executed during
the prepare or optimize phase of the outer query, at the end
of the subquery execution all the JOIN_TABs of the subquery
are replaced by a new JOIN_TAB that selects from the temp table.
However that temp table has no corresponding TABLE_LIST.
Once EXPLAIN execution reaches its last phase, it tries to print
the names of the subquery tables through its TABLE_LISTs, but in
the case of this bug there is no such TABLE_LIST (it is NULL),
hence a crash.
Solution:
The fix is to block subquery evaluation inside
Item_func_like::fix_fields and Item_func_like::select_optimize()
using the Item::is_expensive() test.
Problem
========
Replication breaks in the cases if the event length exceeds
the size of master Dump thread's max_allowed_packet.
The reason why this failure is occuring is because the event length is
more than the total size of the max_allowed_packet, on addition of the
max_event_header length exceeds the max_allowed_packet of the DUMP thread.
This causes the Dump thread to break replication and throw an error.
That can happen e.g with row-based replication in Update_rows event.
Fix
====
The problem is fixed in 2 steps:
1.) The Dump thread limit to read event is increased to the upper limit
i.e. Dump thread reads whatever gets logged in the binary log.
2.) On the slave side we increase the the max_allowed_packet for the
slave's threads (IO/SQL) by increasing it to 1GB.
This is done using the new server option (slave_max_allowed_packet)
included, is used to regulate the max_allowed_packet of the
slave thread (IO/SQL) by the DBA, and facilitates the sending of
large packets from the master to the slave.
This causes the large packets to be received by the slave and apply
it successfully.
sql/log_event.cc:
The max_allowed_packet is not evaluated to the new option
slave_max_allowed_packet after the fix.
sql/log_event.h:
Added the new option in the log_event.h file.
sql/mysqld.cc:
Added a new option to the server.
sql/slave.cc:
Increasing the session max_allowed_packet to a large value,
i.e. not taking global(max_allowed) into consideration, for the slave's threads.
sql/sql_repl.cc:
The dump thread's max_allowed_packet is set to the upper limit
which makes it independent and it now reads whatever gets
logged in the binary log.
- Adding %M my_sprintf() modifier that prints error number - system-error-text
- Modified mysys, mysql_client and SQL error messages to use %M instead of %d
- Added my_strerror()
Updated handler errors to 5.6 error numbers
Updated text for a few error messages (to match 5.6)
Increased length of command name in error output
extra/comp_err.c:
Added support for %M
include/my_base.h:
Updated handler errors to 5.6 error numbers
include/my_sys.h:
Added my_strerror()
libmysql/errmsg.c:
Updated error messages to use %M
mysql-test/r/errors.result:
Updated result as error message have changed
mysql-test/r/innodb_mysql_sync.result:
Updated result with text for errno
mysql-test/r/myisam-system.result:
Updated result with text for errno
mysql-test/r/myisam.result:
Updated result as error message have changed
mysql-test/r/myisampack.result:
Updated result with text for errno
mysql-test/r/mysql.result:
Updated result with text for errno
mysql-test/r/mysql_upgrade.result:
Updated result with text for errno
mysql-test/r/partition_datatype.result:
Updated result as error message have changed
mysql-test/r/partition_innodb_plugin.result:
Updated result with text for errno
mysql-test/r/ps_1general.result:
Updated result with text for errno
mysql-test/r/trigger.result:
Updated result with text for errno
mysql-test/r/type_bit.result:
Updated result as error message have changed
mysql-test/r/type_bit_innodb.result:
Updated result as error message have changed
mysql-test/r/type_blob.result:
Updated result as error message have changed
mysql-test/suite/archive/archive.result:
Updated result with text for errno
mysql-test/suite/binlog/r/binlog_index.result:
Updated result with text for errno
mysql-test/suite/binlog/r/binlog_ioerr.result:
Updated result with text for errno
mysql-test/suite/csv/csv.result:
Updated result with text for errno
mysql-test/suite/federated/federated_bug_35333.result:
Updated result with text for errno
mysql-test/suite/innodb/r/innodb-create-options.result:
Updated result with text for errno
mysql-test/suite/innodb/r/innodb-index.result:
Updated result with text for errno
mysql-test/suite/innodb/r/innodb-zip.result:
Updated result as error message have changed
mysql-test/suite/innodb/r/innodb.result:
Updated result with text for errno
mysql-test/suite/innodb/r/innodb_bug21704.result:
Updated result with text for errno
mysql-test/suite/innodb/r/innodb_bug46000.result:
Updated result with text for errno
mysql-test/suite/innodb/r/innodb_bug53591.result:
Updated result as error message have changed
mysql-test/suite/innodb/r/innodb_corrupt_bit.result:
New error numbers
mysql-test/suite/innodb/r/innodb_prefix_index_liftedlimit.result:
Updated result as error message have changed
mysql-test/suite/innodb/t/innodb-create-options.test:
Added regexp to avoid system error text
mysql-test/suite/innodb/t/innodb-zip.test:
Added regexp to avoid system error text
mysql-test/suite/maria/maria-recovery2.result:
Updated supression rule
mysql-test/suite/maria/maria-recovery2.test:
Updated supression rule
mysql-test/suite/maria/maria.result:
Updated result as error message have changed
mysql-test/suite/parts/r/partition_bit_innodb.result:
Updated result as error message have changed
mysql-test/suite/parts/r/partition_bit_myisam.result:
Updated result as error message have changed
mysql-test/suite/percona/percona_innodb_fake_changes.result:
Updated result with text for errno
mysql-test/suite/perfschema/r/dml_cond_instances.result:
Updated result as error message have changed
mysql-test/suite/perfschema/r/dml_events_waits_current.result:
Updated result as error message have changed
mysql-test/suite/perfschema/r/dml_events_waits_history.result:
Updated result as error message have changed
mysql-test/suite/perfschema/r/dml_events_waits_history_long.result:
Updated result as error message have changed
mysql-test/suite/perfschema/r/dml_ews_by_instance.result:
Updated result as error message have changed
mysql-test/suite/perfschema/r/dml_ews_by_thread_by_event_name.result:
Updated result as error message have changed
mysql-test/suite/perfschema/r/dml_ews_global_by_event_name.result:
Updated result as error message have changed
mysql-test/suite/perfschema/r/dml_file_instances.result:
Updated result as error message have changed
mysql-test/suite/perfschema/r/dml_file_summary_by_event_name.result:
Updated result as error message have changed
mysql-test/suite/perfschema/r/dml_file_summary_by_instance.result:
Updated result as error message have changed
mysql-test/suite/perfschema/r/dml_mutex_instances.result:
Updated result as error message have changed
mysql-test/suite/perfschema/r/dml_performance_timers.result:
Updated result as error message have changed
mysql-test/suite/perfschema/r/dml_rwlock_instances.result:
Updated result as error message have changed
mysql-test/suite/perfschema/r/dml_threads.result:
Updated result as error message have changed
mysql-test/suite/perfschema/r/misc.result:
Updated result with text for errno
mysql-test/suite/perfschema/r/privilege.result:
Updated result with text for errno
mysql-test/suite/rpl/r/rpl_EE_err.result:
Updated result with text for errno
mysql-test/suite/rpl/r/rpl_binlog_errors.result:
Updated result with text for errno
mysql-test/suite/rpl/r/rpl_drop_db.result:
Updated result with text for errno
mysys/errors.c:
Updated error messages to use %M
Changed all errors to use Errcode: consistenly
mysys/my_handler_errors.h:
Updated handler errors to 5.6 error numbers
sql/share/errmsg-utf8.txt:
Updated error messages to use %M
sql/sys_vars.cc:
Added error number to ER_EVENT_SET_VAR_ERROR
strings/my_vsnprintf.c:
Added %M my_sprintf() modifier that prints error number - system-error-text
Simplify code
Movied common code to function
Removed some casts that was not necessary when reading integer/unsigned int stored in longlong
Added my_strerror()
unittest/mysys/my_vsnprintf-t.c:
Added testing of %M
Analysis:
The fix for lp:944706 introduces early subquery optimization.
While a subquery is being optimized some of its predicates may be
removed. In the test case, the EXISTS subquery is constant, and is
evaluated to TRUE. As a result the whole OR is TRUE, and thus the
correlated condition "b = alias1.b" is optimized away. The subquery
becomes non-correlated.
The subquery cache is designed to work only for correlated subqueries.
If constant subquery optimization is disallowed, then the constant
subquery is not evaluated, the subquery remains correlated, and its
execution is cached. As a result execution is fast.
However, when the constant subquery was optimized away, it was neither
cached by the subquery cache, nor it was cached by the internal subquery
caching. The latter was due to the fact that the subquery still appeared
as correlated to the subselect_XYZ_engine::exec methods, and they
re-executed the subquery on each call to Item_subselect::exec.
Solution:
The solution is to update the correlated status of the subquery after it has
been optimized. This status consists of:
- st_select_lex::is_correlated
- Item_subselect::is_correlated
- SELECT_LEX::uncacheable
- SELECT_LEX_UNIT::uncacheable
The status is updated by st_select_lex::update_correlated_cache(), and its
caller st_select_lex::optimize_unflattened_subqueries. The solution relies
on the fact that the optimizer already called
st_select_lex::update_used_tables() for each subquery. This allows to
efficiently update the correlated status of each subquery without walking
the whole subquery tree.
Notice that his patch is an improvement over MySQL 5.6 and older, where
subqueries are not pre-optimized, and the above analysis is not possible.
Optimizator fails using index with ST_Within(g, constant_poly).
per-file comments:
mysql-test/r/gis-rt-precise.result
test result fixed.
mysql-test/r/gis-rtree.result
test result fixed.
mysql-test/suite/maria/r/maria-gis-rtree-dynamic.result
test result fixed.
mysql-test/suite/maria/r/maria-gis-rtree-trans.result
test result fixed.
mysql-test/suite/maria/r/maria-gis-rtree.result
test result fixed.
storage/maria/ma_rt_index.c
Use MBR_INTERSECT mode when optimizing the select WITH ST_Within.
storage/myisam/rt_index.c
Use MBR_INTERSECT mode when optimizing the select WITH ST_Within.
- In JOIN::exec(), make the having->update_used_tables() call before we've
made the JOIN::cleanup(full=true) call. The latter frees SJ-Materialization
structures, which correlated subquery predicate items attempt to walk afterwards.
- Don't try to produce plans after JOIN::cleanup() has been called, because:
= JOIN::cleanup leaves data structures in partially-cleaned state
= Walking them is hazardous (see this bug), and has funny effects
(See previous commits, "Using join cache" may or may not be shown)
= Changing data structures to be persisted may cause unwanted side effects
- The consequence is that SHOW EXPLAIN will show "Query plan already deleted" when e.g.
reading data after filesort.
Details:
- Archive storage engine file access were not instrumented and thus
were not shown in PS tables.
Fix:
- Added instrumentation code by using PS Apis for I/O.
Analysis:
The problem in the original MySQL bug is that the range optimizer
performs its analysis in a separate MEM_ROOT object that is freed
after the range optimzier is done. During range analysis get_mm_tree
calls Item_func_like::select_optimize, which in turn evaluates its
right argument. In the test case the right argument is a subquery.
In MySQL, subqueries are optimized lazyly, thus the call to val_str
triggers optimization for the subquery. All objects needed by the
subquery plan end up in the temporary MEM_ROOT used by the range
optimizer. When execution ends, the JOIN::cleanup process tries to
cleanup objects of the subquery plan, but all these objects are gone
with the temporary MEM_ROOT. The solution for MySQL is to switch the
mem_root.
In MariaDB with the patch for bug lp:944706, all constant subqueries
that may be used by the optimization process are preoptimized. Therefore
Item_func_like::select_optimize only triggers subquery execution, and
the above problem is not present.
The patch however adds a test whether the evaluated right argument of
the LIKE predicate is expensive. This is consistent with our approach
not to evaluate expensive expressions during optimization.
This is a backport of the (unchaged) fix for MySQL bug #11764372, 57197.
Analysis:
When the outer query finishes its main execution and computes GROUP BY,
it needs to construct a new temporary table (and a corresponding JOIN) to
execute the last DISTINCT operation. At this point JOIN::exec calls
JOIN::join_free, which calls JOIN::cleanup -> TMP_TABLE_PARAM::cleanup
for both the outer and the inner JOINs. The call to the inner
TMP_TABLE_PARAM::cleanup sets copy_field = NULL, but not copy_field_end.
The final execution phase that computes the DISTINCT invokes:
evaluate_join_record -> end_write -> copy_funcs
The last function copies the results of all functions into the temp table.
copy_funcs walks over all functions in join->tmp_table_param.items_to_copy.
In this case items_to_copy contains both assignments to user variables.
The process of copying user variables invokes Item_func_set_user_var::check
which in turn re-evaluates the arguments of the user variable assignment.
This in turn triggers re-evaluation of the subquery, and ultimately
copy_field.
However, the previous call to TMP_TABLE_PARAM::cleanup for the subquery
already set copy_field to NULL but not its copy_field_end. This results
in a null pointer access, and a crash.
Fix:
Set copy_field_end and save_copy_field_end to null when deleting
copy fields in TMP_TABLE_PARAM::cleanup().
updating the result file. Because a multi-row insert now reserves the
auto increment values before hand, if any explicitly specified auto
increment values are there, then some of the reserved values are lost.
Analysis:
The optimizer detects an empty result through constant table optimization.
Then it calls return_zero_rows(), which in turns calls inderctly
Item_maxmin_subselect::no_rows_in_result(). The latter method set "value=0",
however "value" is pointer to Item_cache, and not just an integer value.
All of the Item_[maxmin | singlerow]_subselect::val_XXX methods does:
if (forced_const)
return value->val_real();
which of course crashes when value is a NULL pointer.
Solution:
When the optimizer discovers an empty result set, set
Item_singlerow_subselect::value to a FALSE constant Item instead of NULL.
Handle the 'set read_only=1' in lighter way, than the FLUSH TABLES READ LOCK;
For the transactional engines we don't wait for operations on that tables to finish.
per-file comments:
mysql-test/r/read_only_innodb.result
MDEV-136 Non-blocking "set read_only".
test result updated.
mysql-test/t/read_only_innodb.test
MDEV-136 Non-blocking "set read_only".
test case added.
sql/mysql_priv.h
MDEV-136 Non-blocking "set read_only".
The close_cached_tables_set_readonly() declared.
sql/set_var.cc
MDEV-136 Non-blocking "set read_only".
Call close_cached_tables_set_readonly() for the read_only::set_var.
sql/sql_base.cc
MDEV-136 Non-blocking "set read_only".
Parameters added to the close_cached_tables implementation,
close_cached_tables_set_readonly declared.
Prevent blocking on the transactional tables if the
set_readonly_mode is on.
Problem
========
SQL statements close to the size of max_allowed_packet produce binary
log events larger than max_allowed_packet.
The reason why this failure is occuring is because the event length is
more than the total size of the max_allowed_packet + max_event_header
length. Now since the event length exceeds this size master Dump
thread is unable to send the packet on to the slave.
That can happen e.g with row-based replication in Update_rows event.
Fix
====
The problem was fixed by increasing the max_allowed_packet for the
slave's threads (IO/SQL) by increasing it to 1GB.
This is done using the new server option included which is used to
regulate the max_allowed_packet of the slave thread (IO/SQL).
This causes the large packets to be received by the slave and apply
it successfully.
sql/log_event.h:
Added the new option in the log_event.h file.
sql/mysqld.cc:
Added a new option to the server.
sql/slave.cc:
Increasing the session max_allowed_packet to a large value ,
i.e. not taking global(max_allowed) into consideration, for the slave's threads.
Fixed some mtr test problems
dbug/tests.c:
Fixed compiler warnings
mysql-test/r/handlersocket.result:
Fixed that plugin_license is written
mysql-test/suite/innodb/t/innodb_bug60196.test:
Force sorted results as it was sometimes different on windows
mysql-test/suite/rpl/t/rpl_heartbeat_basic.test:
Prolong test as this failed on windows
mysql-test/t/handlersocket.test:
Fixed that plugin_license is written
plugin/handler_socket/handlersocket/handlersocket.cpp:
Use maria_declare_plugin
plugin/handler_socket/handlersocket/mysql_incl.hpp:
Fixed compiler warning
plugin/handler_socket/libhsclient/auto_addrinfo.hpp:
Fixed compiler warning
sql/handler.h:
Fixed typo
sql/sql_plugin.cc:
Fixed bug that caused plugin library name twice in error message
storage/maria/ma_checkpoint.c:
Fixed compiler warning
storage/maria/ma_loghandler.c:
Fixed compiler warning
unittest/mysys/base64-t.c:
Fixed compiler warning
unittest/mysys/bitmap-t.c:
Fixed compiler warning
unittest/mysys/my_malloc-t.c:
Fixed compiler warning
Fix is done by doing an autocommit in truncate table inside Aria
storage/maria/ha_maria.cc:
Force a commit for TRUNCATE TABLE inside lock tables
Check that we don't call TRUNCATE with concurrent inserts going on.
Make ha_maria::implict_commit faster when we don't have Aria tables in the transaction.
(Most of the patch is just re-indentation because I removed an if level)
- make make_cond_after_sjm() correctly handle OR clauses where one branch refers to the semi-join table
while the other branch refers to the non-semijoin table.
The cause for this bug is that the method JOIN::get_examined_rows iterates over all
JOIN_TABs of the join assuming they are just a sequence. In the query above, the
innermost subquery is merged into its parent query. When we call
JOIN::get_examined_rows for the second-level subquery, the iteration that
assumes sequential order of join tabs goes outside the join_tab array and calls
the method JOIN_TAB::get_examined_rows on uninitialized memory.
The fix is to iterate over JOIN_TABs in a way that takes into account the nested
semi-join structure of JOIN_TABs. In particular iterate as select_describe.
The patch enables back constant subquery execution during
query optimization after it was disabled during the development
of MWL#89 (cost-based choice of IN-TO-EXISTS vs MATERIALIZATION).
The main idea is that constant subqueries are allowed to be executed
during optimization if their execution is not expensive.
The approach is as follows:
- Constant subqueries are recursively optimized in the beginning of
JOIN::optimize of the outer query. This is done by the new method
JOIN::optimize_constant_subqueries(). This is done so that the cost
of executing these queries can be estimated.
- Optimization of the outer query proceeds normally. During this phase
the optimizer may request execution of non-expensive constant subqueries.
Each place where the optimizer may potentially execute an expensive
expression is guarded with the predicate Item::is_expensive().
- The implementation of Item_subselect::is_expensive has been extended
to use the number of examined rows (estimated by the optimizer) as a
way to determine whether the subquery is expensive or not.
- The new system variable "expensive_subquery_limit" controls how many
examined rows are considered to be not expensive. The default is 100.
In addition, multiple changes were needed to make this solution work
in the light of the changes made by MWL#89. These changes were needed
to fix various crashes and wrong results, and legacy bugs discovered
during development.
The optimizer chose a less efficient execution plan due to the following
defects of the code:
1. the generic handler function handler::keyread_time did not take into account
that in clustered primary keys record data is included into each index entry
2. the function make_join_readinfo erroneously decided that index only scan
could not be used if join cache was empoyed.
Added no additional test case.
Adjusted some of the test results.
Changed HA_EXTRA_NORMAL to HA_EXTRA_NOT_USED (more clean)
mysql-test/suite/maria/lock.result:
More extensive tests of LOCK TABLE with FLUSH and REPAIR
mysql-test/suite/maria/lock.test:
More extensive tests of LOCK TABLE with FLUSH and REPAIR
sql/sql_admin.cc:
Fix that REPAIR TABLE ... USE_FRM works with LOCK TABLES
sql/sql_base.cc:
Ensure that transactions are closed in ARIA when doing flush
HA_EXTRA_NORMAL -> HA_EXTRA_NOT_USED
Don't call extra many times for a table in close_all_tables_for_name()
Added test if table_list->table as this can happen in error situations
sql/sql_partition.cc:
HA_EXTRA_NORMAL -> HA_EXTRA_NOT_USED
sql/sql_reload.cc:
Fixed comment
sql/sql_table.cc:
HA_EXTRA_NORMAL -> HA_EXTRA_NOT_USED
sql/sql_trigger.cc:
HA_EXTRA_NORMAL -> HA_EXTRA_NOT_USED
sql/sql_truncate.cc:
HA_EXTRA_FORCE_REOPEN -> HA_EXTRA_PREPARE_FOR_DROP for truncate, as this speeds up truncate by not having to flush the cache to disk.
mysql-test/suite/maria/maria-partitioning.result:
New test case
mysql-test/suite/maria/maria-partitioning.test:
New test case
sql/sql_base.cc:
Ignore HA_EXTRA_NORMAL for wait_while_table_is_used()
More DBUG
sql/sql_partition.cc:
Don't use HA_EXTRA_FORCE_REOPEN for wait_while_table_is_used() as the table is opened multiple times (in prep_alter_part_table)
This fixes the assert in Aria where we check if table is opened multiple times if HA_EXTRA_FORCE_REOPEN is issued
