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From:Nikolas Samios Date:December 4 2002 8:37pm
Subject:Re: Slow performance using 3.23 on RH 8.0
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Hi Mike,

i'm a newbie in optimizing the inner structure of a db - so i stick to the
os-part where i might have a vague clue ;-)

did you take a look at the memory / swap-space mysqld used when doing the
query?
(maybe use TOP (add swap to the view by hitting "f" and then "o"), look at
the swapspace used by the mysqld threads, usage of kswapd, loadaverage...)

I once had a lot of performance problems with mysqld 3.23.4x on suse-linux 7
when suddenly the os startet to assign hd-swap-space to some of the mysqld
threads, which slowed down the action dramatically. changing my.cnf didn't
really change the situation - but for testing you could just do "swapoff -a"
and compare the results.

goodluck,
niko


----- Original Message -----
From: "Ledet, Mike" <MLedet@stripped>
To: <mysql@stripped>
Sent: Wednesday, December 04, 2002 5:00 PM
Subject: Slow performance using 3.23 on RH 8.0


> I'm running Mysql 3.23.52 on a Redhat 8.0 installation booting to Gnome.
> The machine is a dual AMD 1800, 1 gig of ram, one Ultra ATA IDE drive, and
2
> 18 gig scsi 10,000 RPM drives on a RAID controller running Raid 0.
>
> I've got everything except /db on the IDE drive, /db is the only thing on
> the raid array.
>
> I've got a couple of smallish tables and one larger table with about 7
gigs
> of data.  The larger table is a fixed row format table with each row being
> 462 bytes wide.  I have a primary auto increment int column and a unique
> index on a varchar 60.  Pack keys is off, delayed key writes on.
>
> With this kind of hardware I was expecting pretty good performance, but I
> haven't seen it yet.  I finally decided something was wrong when I had to
> run an alter table on the 7 gig table, adding 3 columns, a varchar 12, a
> varchar 50, and a datetime columm.... and it took over 10 HOURS to
complete.
>
> That seems way too slow to me...
>
> I've included relevant portions (the uncommented portions) from my.cnf,
the
> OS installation was fairly vanilla, using defaults for just about
> everything.  The file system is ext3.
>
> Any suggestions or things I haven't included that you need?  Sorry if I'm
> doing something really stupid here... relatively new to Linux after a lot
of
> years of windoze.
>
> Thanks in advance
>
> Mike
>
> ********** my.cnf *************
>
> [mysqld]
> port            = 3306
> socket          = /var/lib/mysql/mysql.sock
> datadir         = /db/mysql
> skip-locking
> set-variable    = key_buffer=500M
> set-variable    = max_allowed_packet=2M
> set-variable    = table_cache=512
> set-variable    = sort_buffer=22M
> set-variable    = record_buffer=22M
> set-variable    = thread_cache=8
> # Try number of CPU's*2 for thread_concurrency
> set-variable    = thread_concurrency=6
> set-variable    = myisam_sort_buffer_size=64M
> log-bin
> server-id       = 0
> tmpdir          = /tmp/
> [mysqldump]
> quick
> set-variable    = max_allowed_packet=16M
>
> [mysql]
> no-auto-rehash
> # Remove the next comment character if you are not familiar with SQL
> #safe-updates
>
> [isamchk]
> set-variable    = key_buffer=500M
> set-variable    = sort_buffer=8M
> set-variable    = read_buffer=10M
> set-variable    = write_buffer=30M
>
> [myisamchk]
> set-variable    = key_buffer=500M
> set-variable    = sort_buffer=8M
> set-variable    = read_buffer=10M
> set-variable    = write_buffer=30M
> [mysqlhotcopy]
> interactive-timeout
>
>
>
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Thread
Slow performance using 3.23 on RH 8.0Mike Ledet4 Dec
  • Re: Slow performance using 3.23 on RH 8.0Nikolas Samios4 Dec
  • RE: Slow performance using 3.23 on RH 8.0Adam Nelson4 Dec
  • RE: Slow performance using 3.23 on RH 8.0Adam Nelson4 Dec
  • Re: Slow performance using 3.23 on RH 8.0Mirek Novak5 Dec
RE: Slow performance using 3.23 on RH 8.0Mike Ledet4 Dec
  • Re: Slow performance using 3.23 on RH 8.0Michael T. Babcock5 Dec
RE: Slow performance using 3.23 on RH 8.0Mike Ledet4 Dec
RE: Slow performance using 3.23 on RH 8.0Mike Ledet4 Dec
  • RE: Slow performance using 3.23 on RH 8.0Adam Nelson4 Dec
    • Re: Slow performance using 3.23 on RH 8.0Jeremy Zawodny5 Dec
RE: Slow performance using 3.23 on RH 8.0Mike Ledet4 Dec
  • RE: Slow performance using 3.23 on RH 8.0Adam Nelson4 Dec
RE: Slow performance using 3.23 on RH 8.0Mike Ledet4 Dec
RE: Slow performance using 3.23 on RH 8.0Jan Steinman5 Dec