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From "Sylvain Lebresne (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-5514) Allow timestamp hints
Date Thu, 05 Sep 2013 08:00:56 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-5514?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13758870#comment-13758870
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Sylvain Lebresne commented on CASSANDRA-5514:
---------------------------------------------

bq. Is there any reason we can't extend this to non-clustered columns as well?

I don't a reason why it wouldn't work technically. I'm slightly less sure how useful it will
be in practice. For the partition key columns, I suspect the bloom filter makes it almost
always useless. For non primary-key columns, we only allow conditions on them with either
ALLOW FILTERING or 2ndary indexes. Even for 2ndary indexes, we basically only allow them without
ALLOW FILTERING if there is just one equal condition (on an indexed column). In that latter
case, the index gives us directly rows that does match the condition so the BF should again
remove useless sstables. So if that reasoning is right, it means it would only help with ALLOW
FILTERING. Which doesn't mean we shouldn't do it btw, just trying to think out loud if that's
worth the trouble. 
                
> Allow timestamp hints
> ---------------------
>
>                 Key: CASSANDRA-5514
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-5514
>             Project: Cassandra
>          Issue Type: New Feature
>          Components: API, Core
>            Reporter: Jonathan Ellis
>            Assignee: Marcus Eriksson
>             Fix For: 2.0 beta 1
>
>         Attachments: 0001-CASSANDRA-5514-v1.patch, 0001-CASSANDRA-5514-v2.patch
>
>
> Slice queries can't optimize based on timestamp except for rare cases (CASSANDRA-4116).
 However, many common queries involve an implicit time component, where the application author
knows that he is only interested in data more recent than X, or older than Y.
> We could use the per-sstable max and min timestamps we track to avoid touching cold data
if we could pass a hint to Cassandra about the time range we care about.

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