>Description:
This very basic UPDATE command is very slow in 4.02 :
UPDATE lang2 SET ref_id = 0; (could be also = 1, = 2, etc)
It takes several minutes to run on a 235,000 records table, with high disk
activity (fs_usage reveals many seek/read/write accesses).
For comparison, it takes about 5 seconds to execute with mysql 4.01 with the
exact same database (properly installed on both servers from a dump text
file).
>How-To-Repeat:
A) create this table:
CREATE TABLE lang2 (
code int(11) NOT NULL default '0',
ref_id int(11) unsigned NOT NULL default '0',
infos varchar(200) NOT NULL default '',
motexp varchar(200) NOT NULL default '',
lang_source tinyint(4) default NULL,
lang_target tinyint(4) default NULL,
id int(11) NOT NULL auto_increment,
PRIMARY KEY (id),
KEY code (code),
KEY lang_source (lang_source),
KEY lang_target (lang_target)
) TYPE=MyISAM;
B) Insert > 100,000 rows
C) run this :
UPDATE lang2 SET ref_id = 0;
>Fix:
<how to correct or work around the problem, if known (multiple
lines)>
>Submitter-Id: <submitter ID>
>Originator: Dominique Peretti
>Organization:
La Chose Interactive
>MySQL support: none
>Synopsis: UPDATE table SET column = n extremely slow
>Severity: serious
>Priority: high
>Category: mysql
>Class: sw-bug
>Release: mysql-4.0.2-alpha (basic compilation without stop words)
>Environment:
<machine, os, target, libraries (multiple lines)>
System: Darwin localhost 5.5 Darwin Kernel Version 5.5: Thu May 30 14:51:26
PDT 2002; root:xnu/xnu-201.42.3.obj~1/RELEASE_PPC Power Macintosh powerpc
Some paths: /usr/bin/perl /usr/bin/make /usr/bin/gcc /usr/bin/cc
GCC: Reading specs from /usr/libexec/gcc/darwin/ppc/2.95.2/specs
Apple Computer, Inc. version gcc-937.2, based on gcc version 2.95.2 19991024
(release)
Compilation info: CC='gcc' CFLAGS='' CXX='g++' CXXFLAGS='' LDFLAGS=''
LIBC:
lrwxr-xr-x 1 root wheel 15 Jul 13 13:00 /usr/lib/libc.dylib ->
libSystem.dylib
Configure command: ./configure --prefix=/usr/local/mysql
'--with-comment=Dominique Peretti / no stop words'
--with-extra-charsets=complex --disable-shared
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