[jira] [Updated] (HBASE-12411) Optionally enable p-reads and private readers for compactions

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

     [ https://issues.apache.org/jira/browse/HBASE-12411?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Lars Hofhansl updated HBASE-12411:
----------------------------------
    Summary: Optionally enable p-reads and private readers for compactions  (was: Avoid seek + read completely?)

> Optionally enable p-reads and private readers for compactions
> -------------------------------------------------------------
>
>                 Key: HBASE-12411
>                 URL: https://issues.apache.org/jira/browse/HBASE-12411
>             Project: HBase
>          Issue Type: Improvement
>          Components: Performance
>            Reporter: Lars Hofhansl
>             Fix For: 2.0.0, 0.98.9, 0.99.2
>
>         Attachments: 12411-v2.txt, 12411-v3.txt, 12411.txt
>
>
> 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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