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https://issues.apache.org/jira/browse/CASSANDRA-2894?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13071302#comment-13071302
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Byron Clark commented on CASSANDRA-2894:
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[^CASSANDRA-2894.patch] implements this behavior without the global setting for
count_slice_size.
Behavior is based on the paging done in HintedHandoffManager from the 0.8
branch. The maximum page size is 16384 columns, largely because I have no idea
what a good value for that setting would be.
Assumptions made:
- Using the last column returned from get_slice as the starting column for the
next call to get_slice won't skip over any columns.
> add paging to get_count
> -----------------------
>
> Key: CASSANDRA-2894
> URL: https://issues.apache.org/jira/browse/CASSANDRA-2894
> Project: Cassandra
> Issue Type: Improvement
> Components: API
> Reporter: Jonathan Ellis
> Assignee: Vijay
> Priority: Minor
> Labels: lhf
> Fix For: 1.0
>
> Attachments: CASSANDRA-2894.patch
>
>
> It is non-intuitive that get_count materializes the entire slice-to-count on
> the coordinator node (to perform read repair and > CL.ONE consistency). Even
> experienced users have been known to cause memory problems by requesting
> large counts.
> The user cannot page the count himself, because you need a start and stop
> column to do that, and get_count only returns an integer.
> So the best fix is for us to do the paging under the hood, in
> CassandraServer. Add a limit to the slicepredicate they specify, and page
> through it.
> We could add a global setting for count_slice_size, and document that counts
> of more columns than that will have higher latency (because they make
> multiple calls through StorageProxy for the pages).
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