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'SELECT DISTINCT a,b FROM t1' should not use temp table if there is unique index (or primary key) on a. There are a number of other similar cases that can be calculated without the use of a temp table : multi-part unique indexes, primary keys or using GROUP BY instead of DISTINCT. When a GROUP BY/DISTINCT clause contains all key parts of a unique index, then it is guaranteed that the fields of the clause will be unique, therefore we can optimize away GROUP BY/DISTINCT altogether. This optimization has two effects: * there is no need to create a temporary table to compute the GROUP/DISTINCT operation (or the temporary table will be smaller if only GROUP is removed and DISTINCT stays or if DISTINCT is removed and GROUP BY stays) * this causes the statement in effect to become updatable in Connector/Java because the result set columns will be direct reference to the primary key of the table (instead to the temporary table that it currently references). Implemented a check that will optimize away GROUP BY/DISTINCT for queries like the above. Currently it will work only for single non-constant table in the FROM clause. mysql-test/r/distinct.result: Bug #16458: Simple SELECT FOR UPDATE causes "Result Set not updatable" error - test case mysql-test/t/distinct.test: Bug #16458: Simple SELECT FOR UPDATE causes "Result Set not updatable" error - test case sql/sql_select.cc: Bug #16458: Simple SELECT FOR UPDATE causes "Result Set not updatable" error - disable GROUP BY if contains the fields of a unique index. |
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.. | ||
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-test-run.pl | ||
mysql-test-run.sh | ||
mysql_test_run_new.c | ||
README | ||
README.gcov | ||
resolve-stack | ||
suppress.purify |
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