IQ truncate transaction log file

This page describes how you can truncate the transaction log file in Sybase IQ (so not for ASE !). The procedure is only described for a simplex environment.

According to the Sybase documentation you should truncate the IQ transaction log file once a month or when it's size is more than 100 Mb.

There are a couple of methods available to do this task and two are described here.

Adding -m to the .cfg file (with IQ downtime)

This method requires some down-time, although it's just a few minutes.

Find the location of the transaction log file by looking in the server log file. An example of the name of that file is "IQ1.025.srvlog". Look for the text "Transaction log:".

(The location of the transaction log is specified with the "create database" command.)

Go to the directory where the cfg file for IQ is located, for example:

cd /opt/sybase/admin/IQ1

Shutdown IQ

stop_asiq

Modify the configuration file for the IQ server (example: IQ1.cfg) and add the -m flag to it. You should put that flag somewhere in the top of the file, not at the end.

-n IQ1
-m

-c 48M
-s none
<cut>

Start IQ as you normally do

start_asiq @IQ1.cfg IQ1.db

Then shut it down again.

stop_asiq

You will now notice that the transaction log file no longer exists. Modify the cfg file and remove the -m flag.

Restart IQ. A new transaction log file is automatically created.

With the dbdbackup utility (no downtime)

First create a directory where you would like to keep the transaction log dumpfiles.

mkdir /var/dbbackups/IQ1

Run the dbbackup utility as in the following example

dbbackup -c "uid=<username>;pwd=<password>;eng=<engine name>;dbn=<database name>" -x dump -t
Adaptive Server Anywhere Backup Utility Version 9.0.2.2041
 (2 of 2 pages, 100% complete)
Transaction log truncated
Transaction mirror log truncated
Database backup completed

The next invocation of the dbbackup utility will ask if you would like to replace the previous backup, so it makes sense to rename the backup files and add a timestamp to it.

You can also use -xo in stead of -x to truncate the transaction log, without making a backup.

WARNING: This method should not be used on IQ version 12.5, it may lead to a situation that no checkpoints can be done on the database. You will get the message "checkpoint already in progress".

Note: Sybase recommends that you keep a copy of the old transaction log file around for diagnostic purposes.