gkodinov@mysql.com
7bae0de398
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.
2006-05-09 18:13:01 +03:00
holyfoot@deer.(none)
a920d0df86
bug #15745 (COUNT(DISTINCT CONCAT(x,y)) returns wrong result
2006-03-05 20:48:31 +04:00
serg@serg.mylan
db896a66ca
bad merge fixed
2005-09-15 21:05:42 +02:00
igor@rurik.mysql.com
8c34d8e578
Merge ibabaev@bk-internal.mysql.com:/home/bk/mysql-5.0
...
into rurik.mysql.com:/home/igor/mysql-5.0
2005-08-22 09:40:10 -07:00
pappa@c-4a09e253.1238-1-64736c10.cust.bredbandsbolaget.se
4084c13605
Merge c-4a09e253.1238-1-64736c10.cust.bredbandsbolaget.se:/home/pappa/mysql-4.1
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into c-4a09e253.1238-1-64736c10.cust.bredbandsbolaget.se:/home/pappa/mysql-5.0
2005-08-20 16:38:55 -04:00
igor@rurik.mysql.com
c4f677feb5
Manual merge
2005-08-19 20:21:09 -07:00
igor@rurik.mysql.com
2d32b77693
distinct.test, distinct.result:
...
Added test cases for bug #12625 .
sql_select.cc:
Fixed bug #12625 .
Fixed invalid removal of constant items from the DISTINCT
list in the function create_distinct_group.
2005-08-19 01:57:22 -07:00
monty@mysql.com
15d48525af
Merge mysql.com:/home/my/mysql-4.1
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into mysql.com:/home/my/mysql-5.0
2005-07-28 17:09:54 +03:00
monty@mysql.com
3c12d0ae54
Added end marker for tests to make future merges easier
2005-07-28 03:22:47 +03:00
hf@deer.(none)
6c148a7969
Fix for bug #9764 (DISTINCT IFNULL truncates data)
2005-06-08 20:35:37 +05:00
pem@mysql.com
975061bb5a
Merge 4.1 to 5.0.
2003-12-16 16:12:28 +01:00
antony@ltantony.rdg.cyberkinetica.homeunix.net
fcf96dbb18
WorkLog#1323
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Deprecate the use of TYPE=... Preferred syntax is ENGINE=
2003-12-10 04:31:42 +00:00
pem@mysql.telia.com
6e55a3428a
Post-merge fixes.
2003-09-24 15:26:20 +02:00
monty@mashka.mysql.fi
04c43fca8e
Optimize thai character handling
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Remove sel000xxxx tests
After merge fixes
2003-09-12 04:18:07 +03:00
monty@mashka.mysql.fi
2263e3e51f
Merge with 4.0.14
2003-08-11 22:44:43 +03:00
monty@mashka.mysql.fi
d495656ac5
Cleanups
2003-07-09 00:55:07 +03:00
Sinisa@sinisa.nasamreza.org
ee9237e0d8
missing test case for DISTINCT .. LEFT ..
2003-07-05 16:29:11 +03:00
monty@mashka.mysql.fi
34919a03c4
Added thread variable max_seeks_for_key
...
Change optimizer to prefer key lookups before table scan
Change table scans to be done after tables with constrains on scanned table
2003-06-27 03:04:54 +03:00
monty@mashka.mysql.fi
1f6ecc0cd3
Changed mysql-test to print warnings for not existing table to DROP TABLE
...
Cleaned up test; Removed wrong DROP TABLE commands and use standard table and database names.
changed store_warning() -> push_warning_print()
2003-01-06 01:48:59 +02:00
monty@hundin.mysql.fi
8830eb4aa9
Change of internal key_field=NULL handling to avoid error messages.
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Optimized SELECT DISTINCT ... ORDER BY ... LIMIT
Fixed reference to uninitalized variable
2002-12-03 13:08:25 +02:00
serg@serg.mysql.com
e8c6e2717d
bugfix: DISTINCT with const_item in ORDER BY
2002-09-10 19:23:59 +00:00
Sinisa@sinisa.nasamreza.org
63fb2232d2
Change of test case
2002-09-04 14:13:31 +03:00
Sinisa@sinisa.nasamreza.org
265a10ff77
a fix for a bug with all_fields.elements not being changed by
...
expansion of the wildcards
2002-09-03 23:00:23 +03:00
monty@hundin.mysql.fi
5773b6504a
Fixed bug in blocking handling when compiling with OPENSSL (caused hangup in client code)
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Fixed bug in SELECT DISTINCT ... ORDER BY not-used-column.
Fixed bug in pthread_mutex_trylock with HPUX 11.0
2002-08-17 00:35:51 +03:00
monty@tik.mysql.fi
9d9bcf25e7
Fix sorting of NULL values (Should always be first)
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Fix problem with HAVING and MAX() IS NOT NULL
2002-03-02 09:51:24 +02:00
monty@hundin.mysql.fi
e7575da7bb
Portability fixes
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Added record_rnd_buffer
Added --safe-user-create
Fix for ALTER TABLE RENAME on windows
2001-08-10 17:37:37 +03:00
monty@donna.mysql.com
ce2260586d
Fixed ALTER TABLE on MERGE tables
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Fixed bug in DISTINCT
2001-01-28 21:35:50 +02:00
monty@donna.mysql.com
c0f40d14cc
Added support for hex strings to mysqlimport
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A lot of new tests to mysqltest
Fixed bug with BDB tables and autocommit
2000-12-28 03:56:38 +02:00
