singlestore

SingleStore Updates and Deletes on reference table


I have a reference column-store table in my single store that have roughly 2 million rows and is running on 7 leaf nodes, everyday we get around 10k updates

Now updates are not good on single-store so I came up with 2 approaches:

  1. Do 10k updates everyday
  2. Insert whole 2 million rows everyday once and maintain a version, and read the latest version while reading and then have a cleanup job to delete the previous versions

Now, since this is a reference table, deletions and updations will occur on all the nodes which may block my partitions, is there any safe threshold, or number that I can use, let's say 2k updates every hour won't cause any issues or 10k deletes every hour won't break the system or block my partitions.


Solution

  • Based on your described scenario and your concern for updates causing potential issues or blockages, I'd recommend tuning the default_columnstore_table_lock_threshold. By default, this variable is set to 0, which means a value of 5000 is used. This default configuration already results in partition-level locking only when over 5000 rows in a partition are affected by the UPDATE or DELETE operations.

    However, you can override this threshold by using the OPTION (columnstore_table_lock_threshold = ) hint in your UPDATE and DELETE queries1. For example:

    UPDATE your_table SET column_name = 'new_value'
    WHERE some_condition OPTION (columnstore_table_lock_threshold = 2000);
    

    As for the safe threshold, it really depends on your specific use case and specs. In your case, I wold start with the default configuration and monitor the system performance. Then, adjust the threshold accordingly based on your observed performance and system requirements.