mariadb/mysql-test
unknown baae7a97d9 BUG#18068: SELECT DISTINCT (with duplicates and covering index)
When converting DISTINCT to GROUP BY where the columns are from the covering
index and they are quoted twice in the SELECT list the optimizer is creating
improper processing sequence. This is because of the fact that the columns
of the covering index are not recognized as such and treated as non-index
columns.

Generally speaking duplicate columns can safely be removed from the GROUP
BY/DISTINCT list because this will not add or remove new rows in the
resulting set. Duplicates can be removed even if they are not consecutive
(as is the case for ORDER BY, where the duplicate columns can be removed
only if they are consecutive).

So we can safely transform "SELECT DISTINCT a,a FROM ... ORDER BY a" to
"SELECT a,a FROM ... GROUP BY a ORDER BY a" instead of 
"SELECT a,a FROM .. GROUP BY a,a ORDER BY a". We can even transform 
"SELECT DISTINCT a,b,a FROM ... ORDER BY a,b" to
"SELECT a,b,a FROM ... GROUP BY a,b ORDER BY a,b".

The fix to this bug consists of checking for duplicate columns in the SELECT
list when constructing the GROUP BY list in transforming DISTINCT to GROUP
BY and skipping the ones that are already in.


mysql-test/r/distinct.result:
  test case for the bug without loose index scan
mysql-test/r/group_min_max.result:
  test case for the bug
mysql-test/t/distinct.test:
  test case for the bug without loose index scan
mysql-test/t/group_min_max.test:
  test case for the bug
sql/sql_select.cc:
  duplicates check and removal
2006-05-09 18:13:01 +03:00
..
include Add test to mysql-test-run.pl to see if the udf_example.so is availble. Set envioronment variable UDF_EXAMPLE_LIB if it is. 2006-04-27 16:32:40 +02:00
lib Return empty string if file does not exist 2006-04-27 21:26:24 +02:00
misc
ndb Fix bug in ndbcluster.sh on Solaris (now that line is the same as in 5.1) 2006-04-26 20:50:27 -07:00
r BUG#18068: SELECT DISTINCT (with duplicates and covering index) 2006-05-09 18:13:01 +03:00
std_data Fix for BUG#16266: Definer is not fully qualified error during replication. 2006-03-01 14:13:07 +03:00
suite/jp
t BUG#18068: SELECT DISTINCT (with duplicates and covering index) 2006-05-09 18:13:01 +03:00
create-test-result
fix-result
init_db.sql
install_test_db.sh
Makefile.am Merge 2006-04-03 03:52:22 +02:00
my_create_tables.c
my_manage.c
my_manage.h
mysql-stress-test.pl mysql-stress-test.pl, README.stress: 2006-03-03 12:15:01 -06:00
mysql-test-run.pl Merge bk-internal:/home/bk/mysql-5.0 2006-04-28 08:30:49 +02:00
mysql-test-run.sh Merge tulin@bk-internal.mysql.com:/home/bk/mysql-5.0 2006-04-21 14:02:21 +02:00
mysql_test_run_new.c
README README: 2006-03-01 18:37:41 -06:00
README.gcov README.gcov: 2006-03-01 17:55:10 -06:00
README.stress mysql-stress-test.pl, README.stress: 2006-03-03 12:15:01 -06:00
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