[
https://issues.apache.org/jira/browse/CASSANDRA-1956?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13256992#comment-13256992
]
Vijay commented on CASSANDRA-1956:
----------------------------------
>>> Does this support caching head/tail queries? Or do X and Y have to be
>>> existing column values?
No X and Y doesn't need to existing, they are just markers in the RowCacheKey
(for example if the query has x* -> y* we will have that in the RCK instead of
xeon -> yum)... It does support head and tail queries.
>>> it sounds like this always invalidates on update. Would it be possible to
>>> preserve the current row cache behavior?
Yeah the prototype does the update on write, but the problem is that when there
are a lot of updates block size will increase then initially cached, at some
point we need to split/re-partition it...
> 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-commiting-block-cache.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?
--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators:
https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa
For more information on JIRA, see: http://www.atlassian.com/software/jira
