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Block Structure is the terminology we currently use for the framework that manages and caches data collected and transformed by Block Transformers.  This document proposes a solution to address the issues with the current design for updating and invalidating Block Structure data.

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• Multiple versions in memcached. No longer delete the memcached entry as soon as a new version of the course published. With version identifiers, there may now be multiple entries per course at any given time.  

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• Separate Queue. Have a separate celery queue for CBS updates, so they can be monitored and horizontally scaled in isolation. Decided against this.  See 

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  server JIRA (openedx.atlassian.net) serverId 13fd1930-5608-3aac-a5dd-21b934d3a4b4 key TNL-6324

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• The CBS Update task should:
  • Not recompute the CBS if there is already a cached entry for the latest version.
  • Store the CBS in S3 and update the pointer in SQL.
  • Not store Store the CBS in Memcached as it is an and let the LRU cache and should be maintained by the Readersbased on Reader access.

Transformer Version Updates

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