Troubleshooting

If you experience an issue with SQream DB, there are a few steps to take.

Troubleshooting common issues

Troubleshoot cluster setup and configuration

  1. Note any errors - Make a note of any error you see, or check the logs for errors you might have missed.

Note

Logs are generated per-worker, so you will need to identify the worker on which the error occured, or collect logs from all nodes.

  1. If SQream DB can’t start, start SQream DB on a new storage cluster, with default settings. If it still can’t start, there could be a driver or hardware issue. Contact SQream support.
  2. Reproduce the issue with a standalone SQream DB - starting up a temporary, standalone SQream DB can isolate the issue to a configuration issue, network issue, or similar.
  3. Reproduce on a minimal example - Start a standalone SQream DB on a clean storage cluster and try to replicate the issue if possible.

Troubleshoot connectivity issues

  1. Verify the correct login credentials - username, password, and database name.
  2. Verify the host name and port
  3. Try connecting directly to a SQream DB worker, rather than via the load balancer
  4. Verify that the driver version you’re using is supported by the SQream DB version. Driver versions often get updated together with major SQream DB releases.
  5. Try connecting directly with the built in SQL client. If you can connect with the local SQL client, check network availability and firewall settings.

Troubleshoot query performance

  1. Use SHOW_NODE_INFO to examine which building blocks consume time in a statement. If the query has finished, but the results are not yet materialized in the client, it could point to a problem in the application’s data buffering or a network throughput issue..
  2. If a problem occurs through a 3rd party client, try reproducing it directly with the built in SQL client. If the performance is better in the local client, it could point to a problem in the application or network connection.
  3. Consult the:ref:sql_best_practices guide to learn how to optimize queries and table structures.

Troubleshoot query behavior

  1. Consult the SQL statements and syntax reference to verify if a statement or syntax behaves correctly. SQream DB may have some differences in behavior when compared to other databases.
  2. If a problem occurs through a 3rd party client, try reproducing it directly with the built in SQL client. If the problem still occurs, file an issue with SQream support.

File an issue with SQream support

To file an issue, follow our Gathering information for SQream support guide.

Examining logs

See the Collecting logs and metadata database section of the Gathering information for SQream support guide for information about collecting logs for support.

Start a temporary SQream DB for testing

Starting a SQream DB temporarily (not as part of a cluster, with default settings) can be helpful in identifying configuration issues.

Example:

$ sqreamd /home/rhendricks/raviga_database 0 5000 /home/sqream/.sqream/license.enc

Tip

  • Using nohup and & sends SQream DB to run in the background.

  • It is safe to stop SQream DB at any time using kill. No partial data or data corruption should occur when using this method to stop the process.

    $ kill -9 $SQREAM_PID