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Posted to issues@hbase.apache.org by "Lars Hofhansl (JIRA)" <ji...@apache.org> on 2014/11/03 06:57:34 UTC

[jira] [Commented] (HBASE-12411) Avoid seek + read completely?

    [ https://issues.apache.org/jira/browse/HBASE-12411?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14194280#comment-14194280 ] 

Lars Hofhansl commented on HBASE-12411:
---------------------------------------

We do have "small scan", which force a pread.

> Avoid seek + read completely?
> -----------------------------
>
>                 Key: HBASE-12411
>                 URL: https://issues.apache.org/jira/browse/HBASE-12411
>             Project: HBase
>          Issue Type: Brainstorming
>            Reporter: Lars Hofhansl
>
> In the light of HDFS-6735 we might want to consider refraining from seek + read completely and only perform preads.
> For example currently a compaction can lock out every other scanner over the file which the compaction is currently reading for compaction.
> At the very least we can introduce an option to avoid seek + read, so we can allow testing this in various scenarios.
> This will definitely be of great importance for projects like Phoenix which parallelize queries intra region (and hence readers will used concurrently by multiple scanner with high likelihood.)



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