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Posted to issues@hbase.apache.org by "stack (JIRA)" <ji...@apache.org> on 2016/03/15 00:55:33 UTC

[jira] [Commented] (HBASE-15457) [performance] Save-a-seek; hint HFileReader when Scan is a "Get" Scan

    [ https://issues.apache.org/jira/browse/HBASE-15457?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15194416#comment-15194416 ] 

stack commented on HBASE-15457:
-------------------------------

HFIleBlock has notion of a block 'range'. HFileReaderImpl gets an iterator on the block range on construction. The range is set to be the whole file using offset to start of data minus the tail. It looks hard plumbing in an iterator that was constrained by index content.. Something to consider when doing a Get on a row.... could do an index-based calculation up front.

> [performance] Save-a-seek; hint HFileReader when Scan is a "Get" Scan
> ---------------------------------------------------------------------
>
>                 Key: HBASE-15457
>                 URL: https://issues.apache.org/jira/browse/HBASE-15457
>             Project: HBase
>          Issue Type: Bug
>            Reporter: stack
>
> Have the Scan hint the lower-level Reader when its a 'Get' Scan. Reader is currently doing checks for EOF and when time to load next block on each next invocation. Seems easy enough to return null/end-of-scan if a get-scan and the next block is a different row.
> Prompted by @daniel pol questions/suggestions over on HBASE-15392; see towards the end.



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