[jira] [Commented] (HBASE-10247) Client promises about timestamps

["Lars Hofhansl (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HBASE-10247?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13916298#comment-13916298 ] 

Lars Hofhansl commented on HBASE-10247:
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This would also help with:
* scanning: If we scan files in creation order (starting with the memstore) we can stop when we've seen a key (we know there cannot be a newer one in a later file)
* compactions: we can remove delete markers if we compact a tail (again in time order) of the HFiles.
* probably many more optimization that will pop up

> Client promises about timestamps
> --------------------------------
>
>                 Key: HBASE-10247
>                 URL: https://issues.apache.org/jira/browse/HBASE-10247
>             Project: HBase
>          Issue Type: Brainstorming
>            Reporter: Lars Hofhansl
>            Priority: Minor
>
> This is to start a discussion about timestamp promises declared per table of CF.
> For example if a client promises only monotonically increasing timestamps (or no custom set timestamps) and VERSIONS=1, we can aggressively and easily remove old versions of the same row/fam/col from the memstore before we flush, just by supplying a comparator that ignores the timestamp (i.e. two KV just differing by TS would be considered equal).
> That would increase the performance of counters significantly.



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