It looks like a bug. I was able to repeat it and I had different results for the same join depending on when index was added and values of actual data in tables.
-----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] Sent: Wednesday, October 09, 2002 6:33 PM To: [EMAIL PROTECTED] Subject: NULL sometimes joins to NULL >Description: After adding a key to a nullable column, null values will successfully join through to null values in other tables. This only seems to happen when the index is added after the row contains null values. This affects both MyISAM and InnoDB table types and both binary versions 3.23.42 and 4.0.4. >How-To-Repeat: Run the following queries. The first select will return 0 rows, which is correct. The second select will return a match - but all that was changed was the adding of an index. mysql> create table foo (id int); Query OK, 0 rows affected (0.01 sec) mysql> insert into foo values (null), (0); Query OK, 2 rows affected (0.01 sec) Records: 2 Duplicates: 0 Warnings: 0 mysql> create table bar (id int); Query OK, 0 rows affected (0.00 sec) mysql> insert into bar values (null); Query OK, 1 row affected (0.00 sec) mysql> select * from foo, bar where foo.id = bar.id; Empty set (0.00 sec) mysql> alter table foo add key id (id); Query OK, 2 rows affected (0.01 sec) Records: 2 Duplicates: 0 Warnings: 0 mysql> select * from foo, bar where foo.id = bar.id; +------+------+ | id | id | +------+------+ | NULL | NULL | +------+------+ 1 row in set (0.00 sec) mysql> >Fix: >Submitter-Id: <submitter ID> >Originator: >Organization: >MySQL support: none >Synopsis: adding key makes null columns join >Severity: >Priority: >Category: mysql >Class: >Release: mysql-4.0.4-beta (Source distribution) >Environment: System: Linux db2 2.4.18-64GB-SMP #1 SMP Wed Mar 27 13:58:12 UTC 2002 i686 unknown Architecture: i686 Some paths: /usr/bin/perl /usr/bin/make /usr/bin/gmake /usr/bin/gcc /usr/bin/cc GCC: Reading specs from /usr/lib/gcc-lib/i486-suse-linux/2.95.3/specs gcc version 2.95.3 20010315 (SuSE) Compilation info: CC='gcc' CFLAGS='-O6 -mpentiumpro -fomit-frame-pointer' CXX='gcc' CXXFLAGS='-O6 -mpentiumpro -fomit-frame-pointer -felide-constructors -fno-exceptions -fno-rtti' LDFLAGS='' LIBC: -rwxr-xr-x 1 root root 1394238 Jul 12 08:29 /lib/libc.so.6 -rw-r--r-- 1 root root 25361424 Jul 12 06:58 /usr/lib/libc.a -rw-r--r-- 1 root root 178 Mar 23 2002 /usr/lib/libc.so Configure command: ./configure --prefix=/opt/mysql --enable-assembler --with-mysqld-ldflags=-all-static --disable-shared -with-extra-charsets=none 'CFLAGS=-O6 -mpentiumpro -fomit-frame-pointer' 'CXXFLAGS=-O6 -mpentiumpro -fomit-frame-pointer -felide-constructors -fno-exceptions -fno-rtti' CXX=gcc --------------------------------------------------------------------- Before posting, please check: http://www.mysql.com/manual.php (the manual) http://lists.mysql.com/ (the list archive) To request this thread, e-mail <[EMAIL PROTECTED]> To unsubscribe, e-mail <[EMAIL PROTECTED]> Trouble unsubscribing? Try: http://lists.mysql.com/php/unsubscribe.php Attention: Any views expressed in this message are those of the individual sender, except where the message states otherwise and the sender is authorized to state them to be the views of any such entity. The information contained in this message and or attachments is intended only for the person or entity to which it is addressed and may contain confidential and/or privileged material. Any review, retransmission, dissemination or other use of, or taking of any action in reliance upon, this information by persons or entities other than the intended recipient is prohibited. If you received this in error, please contact the sender and delete the material from any system and destroy any copies. --------------------------------------------------------------------- Before posting, please check: http://www.mysql.com/manual.php (the manual) http://lists.mysql.com/ (the list archive) To request this thread, e-mail <[EMAIL PROTECTED]> To unsubscribe, e-mail <[EMAIL PROTECTED]> Trouble unsubscribing? Try: http://lists.mysql.com/php/unsubscribe.php
