mirror of
https://github.com/MariaDB/server.git
synced 2025-02-01 11:31:51 +01:00
a475ed7c6b
operations) Before this change, the boolean predicates: - X IS TRUE, - X IS NOT TRUE, - X IS FALSE, - X IS NOT FALSE were implemented by expanding the Item tree in the parser, by using a construct like: Item_func_if(Item_func_ifnull(X, <value>), <value>, <value>) Each <value> was a constant integer, either 0 or 1. A bug in the implementation of the function IF(a, b, c), in Item_func_if::fix_length_and_dec(), would cause the following : When the arguments b and c are both unsigned, the result type of the function was signed, instead of unsigned. When the result of the if function is signed, space for the sign could be counted twice (in the max() expression for a signed argument, and in the total), causing the member max_length to be too high. An effect of this is that the final type of IF(x, int(1), int(1)) would be int(2) instead of int(1). With this fix, the problems found in Item_func_if::fix_length_and_dec() have been fixed. While it's semantically correct to represent 'X IS TRUE' with Item_func_if(Item_func_ifnull(X, <value>), <value>, <value>), there are however more problems with this construct. a) Building the parse tree involves : - creating 5 Item instances (3 ints, 1 ifnull, 1 if), - creating each Item calls my_pthread_getspecific_ptr() once in the operator new(size), and a second time in the Item::Item() constructor, resulting in a total of 10 calls to get the current thread. Evaluating the expression involves evaluating up to 4 nodes at runtime. This representation could be greatly simplified and improved. b) Transforming the parse tree internally with if(ifnull(...)) is fine as long as this transformation is internal to the server implementation. With views however, the result of the parse tree is later exposed by the ::print() functions, and stored as part of the view definition. Doing this has long term consequences: 1) The original semantic 'X IS TRUE' is lost, and replaced by the if(ifnull(...)) expression. As a result, SHOW CREATE VIEW does not restore the original code. 2) Should a future version of MySQL implement the SQL BOOLEAN data type for example, views created today using 'X IS NULL' can be exported using mysqldump, and imported again. Such views would be converted correctly and automatically to use a BOOLEAN column in the future version. With 'X IS TRUE' and the current implementations, views using these "boolean" predicates would not be converted during the export/import, and would use integer columns instead. The difference traces back to how SHOW CREATE VIEW preserves 'X IS NULL' but does not preserve the 'X IS TRUE' semantic. With this fix, internal representation of 'X IS TRUE' booleans predicates has changed, so that: - dedicated Item classes are created for each predicate, - only 1 Item is created to represent 1 predicate - my_pthread_getspecific_ptr() is invoked 1 time instead of 10 - SHOW CREATE VIEW preserves the original semantic, and prints 'X IS TRUE'. Note that, because of the fix in Item_func_if, views created before this fix will: - correctly use a int(1) type instead of int(2) for boolean predicates, - incorrectly print the if(ifnull(...), ...) expression in SHOW CREATE VIEW, since the original semantic (X IS TRUE) has been lost. - except for the syntax used in SHOW CREATE VIEW, these views will operate properly, no action is needed. Views created after this fix will operate correctly, and will preserve the original code semantic in SHOW CREATE VIEW. mysql-test/r/func_if.result: IF(x, unsigned, unsigned) should be unsigned. mysql-test/r/view.result: Preserve the semantic of 'X IS [NOT] (TRUE|FALSE)' boolean predicates. mysql-test/t/func_if.test: IF(x, unsigned, unsigned) should be unsigned. mysql-test/t/view.test: Preserve the semantic of 'X IS [NOT] (TRUE|FALSE)' boolean predicates. sql/item_cmpfunc.cc: Preserve the semantic of 'X IS [NOT] (TRUE|FALSE)' boolean predicates. IF(x, unsigned, unsigned) should be unsigned. sql/item_cmpfunc.h: Preserve the semantic of 'X IS [NOT] (TRUE|FALSE)' boolean predicates. sql/sql_yacc.yy: Preserve the semantic of 'X IS [NOT] (TRUE|FALSE)' boolean predicates. |
||
|---|---|---|
| .. | ||
| include | ||
| lib | ||
| misc | ||
| ndb | ||
| r | ||
| std_data | ||
| suite/jp | ||
| t | ||
| create-test-result | ||
| fix-result | ||
| init_db.sql | ||
| install_test_db.sh | ||
| Makefile.am | ||
| my_create_tables.c | ||
| my_manage.c | ||
| my_manage.h | ||
| mysql-stress-test.pl | ||
| mysql-test-run-shell.sh | ||
| mysql-test-run.pl | ||
| mysql_test_run_new.c | ||
| README | ||
| README.gcov | ||
| README.stress | ||
| resolve-stack | ||
| suppress.purify | ||
| 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