Details
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New Feature
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Status: Closed
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Major
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Resolution: Fixed
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0.20.0
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None
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Reviewed
Description
There are a number of use cases where exposing the ability to not cache blocks during a scan would be valuable. For example, running row counts.
The LRU is scan-resistant, so it does provide some protection already, but even in that case all you prevent is the eviction of hot blocks. The LRU still runs many evictions and the blocks are referenced for much longer periods of time, so this adds enormous stress to the GC.
Compactions already do this. This issue is about exposing that as a switch to the client-side Scan object (will also enable it for MR jobs then).