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Bug #20662 "Infinite loop in CREATE TABLE IF NOT EXISTS ... SELECT with locked tables" Bug #20903 "Crash when using CREATE TABLE .. SELECT and triggers" Bug #24738 "CREATE TABLE ... SELECT is not isolated properly" Bug #24508 "Inconsistent results of CREATE TABLE ... SELECT when temporary table exists" Deadlock occured when one tried to execute CREATE TABLE IF NOT EXISTS ... SELECT statement under LOCK TABLES which held read lock on target table. Attempt to execute the same statement for already existing target table with triggers caused server crashes. Also concurrent execution of CREATE TABLE ... SELECT statement and other statements involving target table suffered from various races (some of which might've led to deadlocks). Finally, attempt to execute CREATE TABLE ... SELECT in case when a temporary table with same name was already present led to the insertion of data into this temporary table and creation of empty non-temporary table. All above problems stemmed from the old implementation of CREATE TABLE ... SELECT in which we created, opened and locked target table without any special protection in a separate step and not with the rest of tables used by this statement. This underminded deadlock-avoidance approach used in server and created window for races. It also excluded target table from prelocking causing problems with trigger execution. The patch solves these problems by implementing new approach to handling of CREATE TABLE ... SELECT for base tables. We try to open and lock table to be created at the same time as the rest of tables used by this statement. If such table does not exist at this moment we create and place in the table cache special placeholder for it which prevents its creation or any other usage by other threads. We still use old approach for creation of temporary tables. Also note that we decided to postpone introduction of some tests for concurrent behaviour of CREATE TABLE ... SELECT till 5.1. The main reason for this is absence in 5.0 ability to set @@debug variable at runtime, which can be circumvented only by using several test files with individual .opt files. Since the latter is likely to slowdown test-suite unnecessary we chose not to push this tests into 5.0, but run them manually for this version and later push their optimized version into 5.1 mysql-test/r/create.result: Extended test coverage for CREATE TABLE ... SELECT. In particular added tests for bug #24508 "Inconsistent results of CREATE TABLE ... SELECT when temporary table exists" and bug #20662 "Infinite loop in CREATE TABLE IF NOT EXISTS ... SELECT with locked tables". mysql-test/r/trigger.result: Added test case for bug #20903 "Crash when using CREATE TABLE .. SELECT and triggers" mysql-test/t/create.test: Extended test coverage for CREATE TABLE ... SELECT. In particular added tests for bug #24508 "Inconsistent results of CREATE TABLE ... SELECT when temporary table exists" and bug #20662 "Infinite loop in CREATE TABLE IF NOT EXISTS ... SELECT with locked tables". mysql-test/t/trigger.test: Added test case for bug #20903 "Crash when using CREATE TABLE .. SELECT and triggers" sql/lock.cc: Now for creation of name-lock placeholder in lock_table_name() we use auxiliary function table_cache_insert_placeholder(). sql/mysql_priv.h: Made build_table_path() function available outside of sql_table.cc file. reopen_name_locked_table() now has 3rd argument which controls linking in of table being opened into THD::open_tables (this is useful in cases when placeholder used for name-locking is already linked into this list). Added declaration of auxiliary function table_cache_insert_placeholder() which is used for creation of table placeholders for name-locking. Added declaration of table_cache_has_open_placeholder() function which can be used for checking if table cache contains an open placeholder for the table and if this placeholder was created by another thread. (This function is needed only in 5.0 where we use it in various versions of CREATE TABLE in order to protect it from concurrent CREATE TABLE ... SELECT operations for the table. Starting from 5.1 we use different approach so it is going to be removed there). Made close_old_data_files() static within sql_base.cc file. Added auxiliary drop_open_table() routine. Moved declaration of refresh_version to table.h header to make it accessible from inline methods of TABLE class. MYSQL_OPEN_IGNORE_LOCKED_TABLES flag is no longer used. Instead MYSQL_OPEN_TEMPORARY_ONLY option was added. sql/sql_base.cc: Added support for the new approach to the handling of CREATE TABLE ... SELECT for base tables. Now we try to open and lock table to be created at the same time as the rest of tables used by this statement. If such table does not exist at this moment we create and place in the table cache special placeholder for it which prevents its creation or any other usage by other threads. Note significant distinctions of this placeholder from the placeholder used for normal name-lock: 1) It is treated like open table by other name-locks so it does not allow name-lock taking operations like DROP TABLE or RENAME TABLE to proceed. 2) it is linked into THD::open_tables list and automatically removed during close_thread_tables() call. open_tables(): Implemented logic described above. To do this added auxiliary check_if_table_exists() function. Removed support for MYSQL_OPEN_IGNORE_LOCKED_TABLES option which is no longer used. Added MYSQL_OPEN_TEMPORARY_ONLY which is used to restrict search for temporary tables only. close_cached_tables()/close_thread_table()/reopen_tables()/ close_old_data_files()/table_is_used()/remove_table_from_cache(): Added support for open placeholders (note that we also use them when we need to re-open tables during flush). Added auxiliary drop_open_table() routine. reopen_name_locked_table(): Now has 3rd argument which controls linking in of table being opened into THD::open_tables (this is useful in cases when placeholder used for name-locking is already linked into this list). Added auxiliary table_cache_insert_placeholder() routine which simplifies creation of placeholders used for name-locking. Added table_cache_has_open_placeholder() function which can be used for checking if table cache contains an open placeholder for the table and if this placeholder was created by another thread. (This function is needed only in 5.0 where we use it in various versions of CREATE TABLE in order to protect it from concurrent CREATE TABLE ... SELECT operations for the table. Starting from 5.1 we use different approach so it is going to be removed there). sql/sql_handler.cc: Adjusted mysql_ha_mark_tables_for_reopen() routine to properly handle placeholders which now can be linked into open tables list. sql/sql_insert.cc: Introduced new approach to handling of base tables in CREATE TABLE ... SELECT statement. Now we try to open and lock table to be created at the same time as the rest of tables used by this statement. If such table does not exist at this moment we create and place in the table cache special placeholder for it which prevents its creation or any other usage by other threads. By doing this we avoid races which existed with previous approach in which we created, opened and locked target in separate step without any special protection. This also allows properly calculate prelocking set in cases when target table already exists and has some on insert triggers. Note that we don't employ the same approach for temporary tables (this is okay as such tables are unaffected by other threads). Changed create_table_from_items() and select_create methods to implement this approach. sql/sql_parse.cc: The new approach to handling of CREATE TABLE ... SELECT for base tables assumes that all tables (including table to be created) are opened and (or) locked at the same time. So in cases when we create base table we have to pass to open_and_lock_tables() table list which includes target table. sql/sql_prepare.cc: The new approach to handling of CREATE TABLE ... SELECT for base tables assumes that all tables (including table to be created) are opened and (or) locked at the same time. So in cases when we create base table we have to pass to open_and_lock_tables() table list which includes target table. sql/sql_table.cc: Now mysql_create_table_internal(), mysql_create_like_table() and mysql_alter_table() not only check that destination table doesn't exist on disk but also check that there is no create placeholder in table cache for it (i.e. there is no CREATE TABLE ... SELECT operation in progress for it). Note that starting from 5.1 we use different approach in order to to protect CREATE TABLE ... SELECT from concurrent CREATE TABLE (ALTER TABLE ... RENAME) operations, the latter simply take name-locks on table before its creation (on target table name before renaming). Also made build_table_path() available from other files and asjusted calls to reopen_name_locked_table(), which now takes extra argument, which controls linking of open table into THD::open_tables list. sql/sql_trigger.cc: reopen_name_locked_tables() now has one more argument which controls linking of opened table into the THD::open_tables list. sql/sql_yacc.yy: The new approach to handling of CREATE TABLE ... SELECT statement for base tables assumes that all tables including table to be created are open and (or) locked at the same time. Therefore we need to set correct lock for target table. sql/table.h: Moved declaration of refresh_version variable from mysql_priv.h to make it accessible from inline methods of TABLE class. Renamed TABLE::locked_by_flush member to open_placeholder since now it is also used for taking exclusive name-lock and not only by flush. Introduced TABLE::is_name_opened() helper method which can be used to distinguish TABLE instances corresponding to open tables or placeholders for them from closed instances (e.g. due to their old version). Also introduced TABLE::needs_reopen_or_name_lock() helper which allows to check if TABLE instance corresponds to outdated version of table or to name-lock placeholder. Introduced TABLE_LIST::create member which marks elements of table list corresponds to the table to be created. Adjusted TABLE_LIST::placeholder() method to take into account name-lock placeholders for tables to be created (this, for example, allows to properly handle such placeholders in lock_tables()). |
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| .. | ||
| include | ||
| lib | ||
| misc | ||
| ndb | ||
| r | ||
| std_data | ||
| suite | ||
| t | ||
| create-test-result | ||
| fix-result | ||
| install_test_db.sh | ||
| Makefile.am | ||
| mysql-stress-test.pl | ||
| mysql-test-run-shell.sh | ||
| mysql-test-run.pl | ||
| purify.supp | ||
| README | ||
| README.gcov | ||
| README.stress | ||
| resolve-stack | ||
| valgrind.supp | ||
This directory contains a test suite for the MySQL daemon. To run the currently existing test cases, simply execute ./mysql-test-run in this directory. It will fire up the newly built mysqld and test it. Note that you do not have to have to do "make install", and you could actually have a co-existing MySQL installation. The tests will not conflict with it. All tests must pass. If one or more of them fail on your system, please read the following manual section for instructions on how to report the problem: http://dev.mysql.com/doc/mysql/en/mysql-test-suite.html If you want to use an already running MySQL server for specific tests, use the --extern option to mysql-test-run. Please note that in this mode, the test suite expects you to provide the names of the tests to run. For example, here is the command to run the "alias" and "analyze" tests with an external server: mysql-test-run --extern alias analyze To match your setup, you might also need to provide --socket, --user, and other relevant options. With no test cases named on the command line, mysql-test-run falls back to the normal "non-extern" behavior. The reason for this is that some tests cannot run with an external server. You can create your own test cases. To create a test case, create a new file in the t subdirectory using a text editor. The file should have a .test extension. For example: xemacs t/test_case_name.test In the file, put a set of SQL statements that create some tables, load test data, and run some queries to manipulate it. We would appreciate it if you name your test tables t1, t2, t3 ... (to not conflict too much with existing tables). Your test should begin by dropping the tables you are going to create and end by dropping them again. This ensures that you can run the test over and over again. If you are using mysqltest commands (like result file names) in your test case, you should create the result file as follows: mysql-test-run --record test_case_name or mysqltest --record < t/test_case_name.test If you only have a simple test cases consisting of SQL statements and comments, you can create the test case in one of the following ways: mysql-test-run --record test_case_name mysql test < t/test_case_name.test > r/test_case_name.result mysqltest --record --record-file=r/test_case_name.result < t/test_case_name.test When this is done, take a look at r/test_case_name.result - If the result is incorrect, you have found a bug. In this case, you should edit the test result to the correct results so that we can verify that the bug is corrected in future releases. To submit your test case, put your .test file and .result file(s) into a tar.gz archive, add a README that explains the problem, ftp the archive to ftp://support.mysql.com/pub/mysql/secret/ and send a mail to bugs@lists.mysql.com