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From "Jonathan Ellis (JIRA)" <j...@apache.org>
Subject [jira] [Comment Edited] (CASSANDRA-5514) Allow timestamp hints
Date Thu, 25 Apr 2013 16:48:16 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-5514?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13641939#comment-13641939
] 

Jonathan Ellis edited comment on CASSANDRA-5514 at 4/25/13 4:46 PM:
--------------------------------------------------------------------

Sylvain suggests that instead of adding extra syntax, we track min and max column values (cell
name components) on a per-sstable basis.  The query then just becomes

{code}
SELECT *
FROM mytimeseries
WHERE key = foo
  AND mytimecolumn > X
{code}

This requires less moving pieces to implement (don't need to touch QueryProcessor) and I'm
generally a fan of less special cases.

A small downside is that we'll need to make SSTableMetadata.Collector cql-aware.  Simplest
approach IMO is to just track all the "clustering" components per-sstable, it's not going
to be a whole lot of extra data consumed.
                
      was (Author: jbellis):
    Sylvain suggests that instead of adding extra syntax, we track min and max column values
(cell name components) on a per-sstable basis.  The query then just becomes "SELECT ... WHERE
mytimecolumn > X."  This requires less moving pieces to implement (don't need to touch
QueryProcessor) and I'm generally a fan of less special cases.

A small downside is that we'll need to make SSTableMetadata.Collector cql-aware.  Simplest
approach IMO is to just track all the "clustering" components per-sstable, it's not going
to be a whole lot of extra data consumed.
                  
> 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
>
>
> 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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