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Date: Mon, 13 Jan 2014 14:29:05 +0000 (UTC)
From: "Sylvain Lebresne (JIRA)" <jira@apache.org>
To: commits@cassandra.apache.org
Message-ID: <JIRA.12637544.1363617645910.86723.1389623345394@arcas>
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Subject: [jira] [Commented] (CASSANDRA-5357) Query cache / partition head
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    [ https://issues.apache.org/jira/browse/CASSANDRA-5357?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13869575#comment-13869575 ] 

Sylvain Lebresne commented on CASSANDRA-5357:
---------------------------------------------

bq. Isn't "all rows" just "one row" for a static CF, or did you mean something else?

I guess I'm talking about user convenience. I'm fine making that "all" option just syntactic sugar for Integer.MAX_VALUE. However,  1 row wouldn't work for all queries (you'd need to cache at least 2 rows, so that if you get a "get me all the partition" query, you can say "well, I'm caching the first 2 rows and I have only 1, so I have the full partition in cache"). But wanting to cache a full table (being it static or not btw) is not entirely uncommon so it just feels cleaner to have a 'all' option, rather than requiring user to pick a random big number (it does mean that rows_per_partition can't be just an integer, but since we plan on having an 'auto' mode in the future anyway...). This also give us a good value to default to when upgrading from 2.0 and row cache was enabled on the table.

> Query cache / partition head cache
> ----------------------------------
>
>                 Key: CASSANDRA-5357
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-5357
>             Project: Cassandra
>          Issue Type: New Feature
>            Reporter: Jonathan Ellis
>            Assignee: Marcus Eriksson
>             Fix For: 2.1
>
>         Attachments: 0001-Cache-a-configurable-amount-of-columns-v2.patch, 0001-Cache-a-configurable-amount-of-columns.patch
>
>
> 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.


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