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Constant expressions in WHERE/HAVING/ON clauses aren't cached and evaluated
for each row. This causes slowdown of query execution especially if constant
UDF/SP function are used.
Now WHERE/HAVING/ON expressions are analyzed in the top-bottom direction with
help of the compile function. When analyzer meets a constant item it
sets a flag for the tree transformer to cache the item and doesn't allow tree
walker to go deeper. Thus, the topmost item of a constant expression if
cached. This is done after all other optimizations were applied to
WHERE/HAVING/ON expressions
A helper function called cache_const_exprs is added to the JOIN class.
It calls compile method with caching analyzer and transformer on WHERE,
HAVING, ON expressions if they're present.
The cache_const_expr_analyzer and cache_const_expr_transformer functions are
added to the Item class. The first one check if the item can be cached and
the second caches it if so.
A new Item_cache_datetime class is derived from the Item_cache class.
It caches both int and string values of the underlying item independently to
avoid DATETIME aware int-to-string conversion. Thus it completely relies on
the ability of the underlying item to correctly convert DATETIME value from
int to string and vice versa.
mysql-test/r/func_like.result:
A test case result is corrected after fixing bug#33546.
mysql-test/r/func_time.result:
A test case result is corrected after fixing bug#33546.
mysql-test/r/select.result:
Added a test case for the bug#33546.
mysql-test/r/subselect.result:
A test case result is corrected after fixing bug#33546.
mysql-test/r/udf.result:
Added a test case for the bug#33546.
mysql-test/t/select.test:
Added a test case for the bug#33546.
mysql-test/t/udf.test:
Added a test case for the bug#33546.
sql/item.cc:
Bug#33546: Slowdown on re-evaluation of constant expressions.
The cache_const_expr_analyzer and cache_const_expr_transformer functions are
added to the Item class. The first one check if the item can be cached and
the second caches it if so.
Item_cache_datetime class implementation is added.
sql/item.h:
Bug#33546: Slowdown on re-evaluation of constant expressions.
Item_ref and Item_cache classes now returns basic_const_item
from underlying item.
The cache_const_expr_analyzer and cache_const_expr_transformer functions are
added to the Item class.
sql/sql_select.cc:
Bug#33546: Slowdown on re-evaluation of constant expressions.
A helper function called cache_const_exprs is added to the JOIN class.
It calls compile method with caching analyzer and transformer on WHERE,
HAVING, ON expressions if they're present.
sql/sql_select.h:
Bug#33546: Slowdown on re-evaluation of constant expressions.
A helper function called cache_const_exprs is added to the JOIN class.
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