From 5b225518ff2193834804ddb403ac6c0f9a265884 Mon Sep 17 00:00:00 2001 From: Dmitry Lenev Date: Thu, 16 Jun 2011 19:18:16 +0400 Subject: Fix for bug #12641342 - "61401: UPDATE PERFORMANCE DEGRADES GRADUALLY IF A TRIGGER EXISTS". This bug manifested itself in two ways: - Firstly execution of any data-changing statement which required prelocking (i.e. involved stored function or trigger) as part of transaction slowed down a bit all subsequent statements in this transaction. So performance in transaction which periodically involved such statements gradually degraded over time. - Secondly execution of any data-changing statement which required prelocking as part of transaction prevented concurrent FLUSH TABLES WITH READ LOCK from proceeding until the end of transaction instead of end of particular statement. The problem was caused by incorrect handling of metadata lock used in FTWRL implementation for statements requiring prelocked mode. Each statement which changes data acquires global IX lock with STATEMENT duration. This lock is supposed to block concurrent FTWRL from proceeding until the statement ends. When entering prelocked mode, durations of all metadata locks acquired so far were changed to EXPLICIT, to prevent substatements from releasing these locks. When prelocked mode was left, durations of metadata locks were changed to TRANSACTIONAL (with a few exceptions) so they can be properly released at the end of transaction. Unfortunately, this meant that the global IX lock blocking FTWRL with STATEMENT duration was moved to TRANSACTIONAL duration after execution of statement requiring prelocking. Since each subsequent statement that required prelocking and tried to acquire global IX lock with STATEMENT duration got a new instance of MDL_ticket, which was later moved to TRANSACTIONAL duration, this led to unwarranted growth of number of tickets with TRANSACITONAL duration in this connection's MDL_context. As result searching for other tickets in it became slow and acquisition of other metadata locks by this transaction started to hog CPU. Moreover, this also meant that after execution of statement requiring prelocking concurrent FTWRL was blocked until the end of transaction instead of end of statement. This patch solves this problem by not moving locks to EXPLICIT duration when thread enters prelocked mode (unless it is a real LOCK TABLES mode). This step turned out to be not really necessary as substatements don't try to release metadata locks. Consequently, the global IX lock blocking FTWRL keeps its STATEMENT duration and is properly released at the end of statement and the above issue goes away. mysql-test/r/flush.result: Added test for bug #12641342 - "61401: UPDATE PERFORMANCE DEGRADES GRADUALLY IF A TRIGGER EXISTS". mysql-test/t/flush.test: Added test for bug #12641342 - "61401: UPDATE PERFORMANCE DEGRADES GRADUALLY IF A TRIGGER EXISTS". sql/mdl.h: Added comment describing various types of metadata lock duration. sql/sql_class.cc: Since we no longer change duration of metadata locks to EXPLICIT when entering prelocked mode (unless it is a real LOCK TABLES) there is no need to restore proper duration of the locks when leaving prelocked mode. sql/sql_class.h: Do not change duration of metadata locks to EXPLICIT when entering prelocking mode (unless it is a real LOCK TABLES). This allows to avoid problems with restoring correct duration when leaving this mode. It is possible to do this as substatements won't release metadata locks in any case. sql/sql_parse.cc: Added assert checking that we won't release metadata locks when in substatement. --- sql/sql_class.h | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) (limited to 'sql/sql_class.h') diff --git a/sql/sql_class.h b/sql/sql_class.h index a2c622b2326..8a427057d83 100644 --- a/sql/sql_class.h +++ b/sql/sql_class.h @@ -2795,7 +2795,19 @@ public: { DBUG_ASSERT(locked_tables_mode == LTM_NONE); - mdl_context.set_explicit_duration_for_all_locks(); + if (mode_arg == LTM_LOCK_TABLES) + { + /* + When entering LOCK TABLES mode we should set explicit duration + for all metadata locks acquired so far in order to avoid releasing + them till UNLOCK TABLES statement. + We don't do this when entering prelocked mode since sub-statements + don't release metadata locks and restoring status-quo after leaving + prelocking mode gets complicated. + */ + mdl_context.set_explicit_duration_for_all_locks(); + } + locked_tables_mode= mode_arg; } void leave_locked_tables_mode(); -- cgit v1.2.1 From 44135d4725dd3ad6d331c60b0bab1618472b8ae4 Mon Sep 17 00:00:00 2001 From: Kent Boortz Date: Thu, 30 Jun 2011 17:31:31 +0200 Subject: Updated/added copyright headers --- sql/sql_class.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'sql/sql_class.h') diff --git a/sql/sql_class.h b/sql/sql_class.h index 70086e2d944..4413571f2eb 100644 --- a/sql/sql_class.h +++ b/sql/sql_class.h @@ -1,4 +1,4 @@ -/* Copyright (c) 2000, 2010, Oracle and/or its affiliates. All rights reserved. +/* Copyright (c) 2000, 2011, Oracle and/or its affiliates. All rights reserved. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -11,7 +11,7 @@ You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software - Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */ + Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */ /* Classes in mysql */ -- cgit v1.2.1 From 71e0ff64f070b7ebcf9c25d7c9e75a0aa4970163 Mon Sep 17 00:00:00 2001 From: Davi Arnaut Date: Thu, 7 Jul 2011 08:22:43 -0300 Subject: Bug#12727287: Maintainer mode compilation fails with gcc 4.6 GCC 4.6 has new -Wunused-but-set-variable flag, which is enabled by -Wall, that causes GCC to emit a warning whenever a local variable is assigned to, but otherwise unused (aside from its declaration). Since the maintainer mode uses -Wall and -Werror, source code which triggers these warnings will be rejected. That is, these warnings become hard errors. The solution is to fix the code which triggers these specific warnings. In most of the cases, this is a welcome cleanup as code which triggers this warning is probably dead anyway. dbug/dbug.c: Unused but set. libmysqld/lib_sql.cc: Length is not necessary as the converted error message is always null-terminated. sql/item_func.cc: Make get_var_with_binlog private to this compilation unit. If a error was raised, do not attempt to evaluate the user variable as the statement execution will be interrupted anyway. sql/mysqld.cc: Use a void expression to silence the warning. Avoids the use of macros that would make the code more unreadable than it already is. sql/protocol.cc: Length is not necessary as the converted error message is always null-terminated. Remove unnecessary casts and assignment. sql/sql_class.h: Function is only used in a single compilation unit. sql/sql_load.cc: Only use the variable outside of EMBEDDED_LIBRARY. storage/innobase/btr/btr0cur.c: Do not retrieve field, only the record length is being used. storage/perfschema/pfs.cc: Use a void expression to silence the warning. tests/mysql_client_test.c: Unused but set. unittest/mysys/lf-t.c: Unused but set. --- sql/sql_class.h | 8 -------- 1 file changed, 8 deletions(-) (limited to 'sql/sql_class.h') diff --git a/sql/sql_class.h b/sql/sql_class.h index 8a427057d83..fafbab07979 100644 --- a/sql/sql_class.h +++ b/sql/sql_class.h @@ -3642,14 +3642,6 @@ void add_diff_to_status(STATUS_VAR *to_var, STATUS_VAR *from_var, STATUS_VAR *dec_var); void mark_transaction_to_rollback(THD *thd, bool all); -/* - This prototype is placed here instead of in item_func.h because it - depends on the definition of enum_sql_command, which is in this - file. - */ -int get_var_with_binlog(THD *thd, enum_sql_command sql_command, - LEX_STRING &name, user_var_entry **out_entry); - /* Inline functions */ inline bool add_item_to_list(THD *thd, Item *item) -- cgit v1.2.1 From 3468b55a215d1c4b489dbb925f19176e12c9f242 Mon Sep 17 00:00:00 2001 From: Sergey Glukhov Date: Tue, 2 Aug 2011 11:33:45 +0400 Subject: Bug#11766594 59736: SELECT DISTINCT.. INCORRECT RESULT WITH DETERMINISTIC FUNCTION IN WHERE C There is an optimization of DISTINCT in JOIN::optimize() which depends on THD::used_tables value. Each SELECT statement inside SP resets used_tables value(see mysql_select()) and it leads to wrong result. The fix is to replace THD::used_tables with LEX::used_tables. mysql-test/r/sp.result: test case mysql-test/t/sp.test: test case sql/sql_base.cc: THD::used_tables is replaced with LEX::used_tables sql/sql_class.cc: THD::used_tables is replaced with LEX::used_tables sql/sql_class.h: THD::used_tables is replaced with LEX::used_tables sql/sql_insert.cc: THD::used_tables is replaced with LEX::used_tables sql/sql_lex.cc: THD::used_tables is replaced with LEX::used_tables sql/sql_lex.h: THD::used_tables is replaced with LEX::used_tables sql/sql_prepare.cc: THD::used_tables is replaced with LEX::used_tables sql/sql_select.cc: THD::used_tables is replaced with LEX::used_tables --- sql/sql_class.h | 7 ------- 1 file changed, 7 deletions(-) (limited to 'sql/sql_class.h') diff --git a/sql/sql_class.h b/sql/sql_class.h index bf197fee9c3..3c1b2c1330f 100644 --- a/sql/sql_class.h +++ b/sql/sql_class.h @@ -1734,13 +1734,6 @@ public: */ ha_rows examined_row_count; - /* - The set of those tables whose fields are referenced in all subqueries - of the query. - TODO: possibly this it is incorrect to have used tables in THD because - with more than one subquery, it is not clear what does the field mean. - */ - table_map used_tables; USER_CONN *user_connect; CHARSET_INFO *db_charset; /* -- cgit v1.2.1