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
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