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How can I get TDV to recognize existing data in cache table

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There are a few different reasons that data might exist in a cache table but TDV doesn't know about it. For example, I want to switch the cache from one view to a copy of that same view. The cache table exists with data already in it on the original version, I disable the cache on that version, and enable a cache on the copy and point it to the same cache table. The data already exists in the cache table, but the new copy's cache state is "Never loaded". Is there a way to change the cache state to "Up" without actually running the cache?

This becomes a huge problem in instances where ALL our caches claim to be "Never loaded" (for example, a restore caused us to revert to a snapshot, or some other kind of hard reboot sequence of events caused our external cache database to be disconnected from TDV). It takes days to get all the caches back up, some of them require special authentication to run, it's a mess. And all the data is actually still there, TDV just doesn't know about it.

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  • 2 weeks later...

A revert of snapshot or hard reboot of server causes the cache refresh status to show 'Never loaded' because TDV is not sure if data has changed in the datasource since the last refresh. If TDV cache just checks the cached data in the external database and changes the status to 'UP', there are high chances that the data in the cache provides stale data which might be even before the last scheduled refresh.

There are a few suggestions I would recommend:

  1. For caches where you just need to have a delta data load, implement incremental cache load which will refresh the cache with only updated data in datasource in the next scheduled refresh.
  2. Do not define individual caches on every view, instead define cache policies as per requirement of various kind of refreshes(clusters for every hour, a few hours or day etc) and link cached views in line with the requirement. 

First step will help you refresh cache faster. Second will help you with a single area to track manage all your caches in a centralised location. So, next time your caches says 'Never loaded' dues to network failure, snapshot restore, you can just come to the centralise location and refresh them. You will be able to start refresh for multiple caches like this and do not miss any.

You may refer below documents for reference:

Incremental caching: https://docs.tibco.com/pub/tdv/8.6.0/doc/html/en-US/StudioHelp/index.html#page/StudioHelp%2FCh_16_Caching_6.StudioHelp.html

Cache Policy: https://docs.tibco.com/pub/tdv/8.6.0/doc/html/en-US/StudioHelp/index.html#page/StudioHelp%2FCh_16_Caching_30.StudioHelp.html


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