InnoDB does purge deleted rows from the ibdata files. Certain
PostgreSQL advocates have been spreading a claim that InnoDB would not
do that, but the claim is false.
If your ibdata file keeps growing indefinitely, please check with SHOW
INNODB STATUS that you do commit all your transactions. If a
transaction stays open for months, then the purge cannot remove
deleted rows.
If you convert ALL your tables from InnoDB to MyISAM, then you can
remove the ibdata files and ib_logfiles. If you put skip-innodb to
my.cnf, then those files will not be created again.
I don't think there is a question as to whether or not InnoDB will purge
data and re-use space, the question is whether or not the ibdata files
will be "shrunk" when that space is purged.
My understanding (and experience) has always shown that ibdata files -
while they may purge and re-use unused space, will not shrink themselves
based on the actual space usage. Is that not correct?
I.e., if I have 100 MB of table data, and say - delete 6 tables (which
would result in InnoDB recovering all that space), that results in only
10MB of space being "used", the file will be re-sized to 10MB - or
something smaller than 100 MB.
The practical example would be if I were to accidentally add 1GB of data
to my InnoDB tablespace, and then remove it. Would my total ibdata file
sizes total less than 1GB of space (now I'm just using 100MB)?
If that were the case it would be a simple matter of switching to
'tablespace per table', migrating the data to the individual tables
(which would shrink the ibdata files), re-structuring the ibdata files
(to use other partitions, etc.) an the moving the data back into the
tablespace.
Thanks
--
Chander Ganesan
Open Technology Group, Inc.
One Copley Parkway, Suite 210
Morrisville, NC 27560
Phone: 877-258-8987/919-463-0999
http://www.otg-nc.com
Best regards,
Heikki
Oracle Corp./Innobase Oy
InnoDB - transactions, row level locking, and foreign keys for MySQL
InnoDB Hot Backup - a hot backup tool for InnoDB which also backs up
MyISAM tables
http://www.innodb.com/order.php
----- Original Message ----- From: "Alex" <[EMAIL PROTECTED]>
Newsgroups: mailing.database.myodbc
Sent: Tuesday, January 03, 2006 6:55 AM
Subject: Re: removing ibdata1 if some/all tables are not InnoDB?
HI Carl,
The ibdata file growth can be stopped by removing the autoextend
keyword in the my.cnf file.
In your my.cnf file the entry might be
innodb_data_file_path = ibdata1:256M:autoextend
If you want to stop the growth of that file and add another file then
this
is what you want to do.
1. Stop the mysql server
2. Get the size of the ibdata1 file in MB (Lets say its 5600MB in size)
3. edit the my.cnf file and replace
innodb_data_file_path = ibdata1:256M:autoextend
with
innodb_data_file_path = ibdata1:5600M;ibdata2:256M:autoextend
4. Start the server.
This will stop that file from growing and a new file will be added that
can pushed on to a different disk and symlinked into the ibdata
directory.
Data growth is a problem in all table types. Even if you migrate to
MyISAM
you need space.
See whether there is log_bin turned on the server. If so there might be
lots of bin log files that you can do a cleanup on. Bin logs occupy a
great deal of space.
Thanx
Alex,
MySQL DBA
Yahoo!
On Tue, 03 Jan 2006 08:28:24 +0530, Carl Brewer <[EMAIL PROTECTED]>
wrote:
Hello,
I'm stuck with a rapidly decreasing amount of available disk space and
a requirement to keep a lid on the size of our databases. We're
using MySQL 4.1.12 as bundled with RHEL ES 4. We do a lot of
transactions keeping short term track of webserver sessions, which
we don't need to keep logs of for very long.
I have a number of databases, almost all of which are using MyISAM or
HEAP, and one database using InnoDB. As such (or at least, as I
understand it) we have a ibdata1 file that will grow forever and
AFAIK there's no way to stop it growing forever for as long
as we have that InnoDB database. Am I correct? I'm no MySQL
guru, my parsing of TFM and googling around and finding bug and feature
requests for ibdata1 purging suggests that this is the case.
If so, if I drop the InnoDB database, stop mysqld, delete (UNIX
filesystem) the imdata1 file, restart mysqld and import a
(modified to be MyISAM) dumped copy of the InnoDB database,
will that work without damaging anything and then not leave me
with another infinatly growing imdata1 file?
Am I correct in assuming that InnoDB databases are meant
for sites where disk space is not ever likely to be an
issue, and MyISAM is a more suitable database engine for
our much tighter disk space situation? I may have missed
a section of the doco that discusses why one would choose an
engine over another?
Thanks for any advice,
Carl
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