Jeff S Wheeler writes:
> Tried to post this to mailing.database.mysql, but earthlink's news servers
> suck, and it seems the message got dropped. Bleh. Anyway..:
>
> Jeff S Wheeler <[EMAIL PROTECTED]> wrote in message news:...
> Below is a filled-out mysqlbug form. Indexes on HEAP tables are ignored in
> numerous queries in which I think they should be utilized, but this is the
> first I've noticed where mysql actually _does_ use the index, and as a
> result it produces wrong query results.
>
> Description:
> Adding an index to a HEAP table breaks WHERE col LIKE "502-%"
>
> How-To-Repeat:
> mysql> SELECT COUNT(*) FROM t4 WHERE BillN LIKE "502-%"\G
> *************************** 1. row ***************************
> COUNT(*): 4378
> 1 row in set (0.03 sec)
>
> mysql> CREATE INDEX BillN ON t4 (BillN);
> Query OK, 42854 rows affected (0.15 sec)
>
>
> mysql> SELECT COUNT(*) FROM t4 WHERE BillN LIKE "502-%"\G
> *************************** 1. row ***************************
> COUNT(*): 0
> 1 row in set (0.00 sec)
>
> Fix:
> Do not use indexes on HEAP tables. Of course, I really would like to
> be able to use them, as I have a nasty LEFT JOIN that would be really
> fast in comparison, if it wouldn't improperly return zero rows.
>
> Submitter-Id:
> Originator: Jeff S Wheeler <[EMAIL PROTECTED]>
> Organization: Five Elements, Inc.
> MySQL support: none
> Synopsis: Indexes break some queries on HEAP tables
> Severity: serious
> Priority: low
> Category: mysql
> Class: sw-bug
> Release: mysql-3.23.33-pc-linux-gnu-i686 (Binary distribution)
>
> Environment:
>
> System: Linux neptune 2.4.2 #2 SMP Tue Mar 13 22:15:19 EST 2001 i686 unknown
> Architecture: i686
>
> Some paths: /usr/bin/perl /usr/bin/make /usr/bin/gcc /usr/bin/cc
> GCC: Reading specs from /usr/lib/gcc-lib/i386-linux/2.95.2/specs
> gcc version 2.95.2 20000220 (Debian GNU/Linux)
> Compilation info: CC='gcc' CFLAGS='-O2 -fomit-frame-pointer' CXX='g++'
> CXXFLAGS='-O2 -fomit-frame-pointer -felide-constructors -fno-exceptions -fno
> -rtti' LDFLAGS=''
> Configure command:
> ./configure --enable-shared --without-readline --enable-assembler --with-my
> sqld-user=mysql --with-unix-socket-path=/var/run/mysqld/mysqld.sock --prefix
> =/usr --exec-prefix=/usr --libexecdir=/usr/sbin --sysconfdir=/etc/mysql --da
> tadir=/usr/share --localstatedir=/var/lib/mysql --infodir=/usr/share/info --
> includedir=/usr/include --mandir=/usr/share/man
> Perl: This is perl, version 5.005_03 built for i386-linux
>
>
Hi!
Our manual specifies very clearly that indices in HEAP tables can be
used only for = and !=.
Therefore, for the case like above, you are better without it.
Regards,
Sinisa
____ __ _____ _____ ___ == MySQL AB
/*/\*\/\*\ /*/ \*\ /*/ \*\ |*| Sinisa Milivojevic
/*/ /*/ /*/ \*\_ |*| |*||*| mailto:[EMAIL PROTECTED]
/*/ /*/ /*/\*\/*/ \*\|*| |*||*| Larnaca, Cyprus
/*/ /*/ /*/\*\_/*/ \*\_/*/ |*|____
^^^^^^^^^^^^/*/^^^^^^^^^^^\*\^^^^^^^^^^^
/*/ \*\ Developers Team
---------------------------------------------------------------------
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
