Backtrace Information

This article explains how to generate backtrace logs on your Exasol system.

If you are experiencing performance problems or operations that hang, you need to provide all the backtrace information for the time period when the problem occurred.

Prerequisites

You must have enough free disk space for the logs. For more information, see EXAsupport.

Procedure

The following examples use ConfD through the command-line tool confd_client, which is available on all database nodes. For more information, see ConfD.

Placeholder values are indicated with UPPERCASE characters. Replace the placeholders with your own values.

  1. Connect to EXAClusterOS (COS) on the cluster using c4 connect -t <DEPLOYMENT>[.<NODE>]/cos. For example:

    ./c4 connect -t 1.11/cos

    If you do not specify a node, c4 will connect to the first active node in the deployment.

    For more information about how to use c4 connect, see How to use c4.

  2. To find the name of the database, use the ConfD job db_list. For example:

    confd_client db_list
    - MY_DATABASE

  3. To create a backtrace log, use the EXAsupport tool . Specify the start date (-s) and end date (-t) using the format YYYY-MM-DD. For example:

    exasupport -s 2022-08-11 -t 2022-08-11 -e MY_DATABASE -b1,2,3,4

    If the log file was successfully created, you will see the following message containing the file name:

    Successfully stored debug information into file /exa/tmp/support/exacluster_debuginfo_2022_08_11-23_27_20.tar.gz
  4. Use CTRL+D or type exit to disconnect from COS.

  5. Copy the log file to your local computer by connecting to COS and using the cat command:

    ./c4 connect -t <DEPLOYMENT>.<NODE>/cos -- "cat /exa/tmp/support/$FILENAME" > $FILENAME
    Example: 
    ./c4 connect -t 1.11/cos -- "cat /exa/tmp/support/my_log" > my_log

Verification

To verify that the log was successfully copied, use the ls command in the target folder on your local machine.

Example
ls -lahtr ~/mylogs | grep exacluster_debuginfo
-rwxr-xr-x  1 user group 9.8K Sep 20 17:38 exacluster_debuginfo_2022_08_11-23_27_20.tar.gz