[
https://issues.apache.org/jira/browse/CASSANDRA-5357?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13777088#comment-13777088
]
Vijay commented on CASSANDRA-5357:
----------------------------------
{quote}
So the cost is quite high vs having live filters
{quote}
Some synthetic test show very low over head on the filter deserialization
http://pastebin.com/VNREA8fG.
IMHO... Exist check might not be that bad, since 99% (thats a assumption) of
the queries will have the same query filters on them. For those queries which
are discreet and present in the cache (survived the LRU), i think it is fair to
take a hit than letting it live in JVM.
Filters may be big in some cases (like named filters, or filters with long
string names) and even an optimal case of empty strings we still need a minimum
of 2 BB, count and the data structures in memory. Hence a compact storage
off-heap might be good.
One other option which we where discussing little earlier, to optimize the
filters in the cache by trying to find the optimal cache filter entry by
merging similar and overlapping queries will help the above.
{quote}
I'm not concerned about that so much as, do we keep within our total memory
budget?
{quote}
Ahaa got it, so we need an additional parameter for the cache which says how
much memory is available in the JVM for the cached keys... i will add it to the
next revision.
> Query cache
> -----------
>
> Key: CASSANDRA-5357
> URL: https://issues.apache.org/jira/browse/CASSANDRA-5357
> Project: Cassandra
> Issue Type: Bug
> Reporter: Jonathan Ellis
> Assignee: Vijay
>
> I think that most people expect the row cache to act like a query cache,
> because that's a reasonable model. Caching the entire partition is, in
> retrospect, not really reasonable, so it's not surprising that it catches
> people off guard, especially given the confusion we've inflicted on ourselves
> as to what a "row" constitutes.
> I propose replacing it with a true query cache.
--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators
For more information on JIRA, see: http://www.atlassian.com/software/jira
