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https://issues.apache.org/jira/browse/CASSANDRA-1956?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13180093#comment-13180093
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Daniel Doubleday commented on CASSANDRA-1956:
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Nice try :-)
I was Mr I dont believe in magic from the very beginning. I thought that there
are some common cases like tail and head caching or exclusion of columns that
could be implemented. But never mind - maybe the proposed cache is all
greatness. All I'm trying to say is that it's pretty easy to end up in
propagation failure hell here or change something else that blows things up for
use cases that are not foreseen.
So to prevent a rude awakening for some users it might be cool to provide some
means (config or whatever) that works similar as the current version. Or at
least schedule this for a release which allows for a downgrade.
Just saying ...
> Convert row cache to row+filter cache
> -------------------------------------
>
> Key: CASSANDRA-1956
> URL: https://issues.apache.org/jira/browse/CASSANDRA-1956
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Reporter: Stu Hood
> Assignee: Vijay
> Priority: Minor
> Fix For: 1.2
>
> Attachments: 0001-1956-cache-updates-v0.patch,
> 0001-re-factor-row-cache.patch, 0001-row-cache-filter.patch,
> 0002-1956-updates-to-thrift-and-avro-v0.patch, 0002-add-query-cache.patch
>
>
> Changing the row cache to a row+filter cache would make it much more useful.
> We currently have to warn against using the row cache with wide rows, where
> the read pattern is typically a peek at the head, but this usecase would be
> perfect supported by a cache that stored only columns matching the filter.
> Possible implementations:
> * (copout) Cache a single filter per row, and leave the cache key as is
> * Cache a list of filters per row, leaving the cache key as is: this is
> likely to have some gotchas for weird usage patterns, and it requires the
> list overheard
> * Change the cache key to "rowkey+filterid": basically ideal, but you need a
> secondary index to lookup cache entries by rowkey so that you can keep them
> in sync with the memtable
> * others?
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