FAQ
Show Block cache hit ratio for requests where cacheBlocks=true
--------------------------------------------------------------

Key: HBASE-2253
URL: https://issues.apache.org/jira/browse/HBASE-2253
Project: Hadoop HBase
Issue Type: Improvement
Reporter: Dave Latham
Priority: Minor


We've been disabling block caching for MR jobs and other big scans. It seems to improve cache performance, but it's difficult to measure the hit ratio because even scans that don't cache blocks still request blocks from the cache (which is good), and those requests affect the hit/miss stats, which makes it difficult to see how the queries where cacheBlocks=true are performing.

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  • Jean-Daniel Cryans (JIRA) at Feb 23, 2010 at 7:57 pm
    [ https://issues.apache.org/jira/browse/HBASE-2253?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12837417#action_12837417 ]

    Jean-Daniel Cryans commented on HBASE-2253:
    -------------------------------------------

    One point of discussion here is whether we should only show the hit rate for cacheBlocks=true or both.
    Show Block cache hit ratio for requests where cacheBlocks=true
    --------------------------------------------------------------

    Key: HBASE-2253
    URL: https://issues.apache.org/jira/browse/HBASE-2253
    Project: Hadoop HBase
    Issue Type: Improvement
    Reporter: Dave Latham
    Priority: Minor

    We've been disabling block caching for MR jobs and other big scans. It seems to improve cache performance, but it's difficult to measure the hit ratio because even scans that don't cache blocks still request blocks from the cache (which is good), and those requests affect the hit/miss stats, which makes it difficult to see how the queries where cacheBlocks=true are performing.
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  • ryan rawson (JIRA) at Feb 23, 2010 at 8:19 pm
    [ https://issues.apache.org/jira/browse/HBASE-2253?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12837425#action_12837425 ]

    ryan rawson commented on HBASE-2253:
    ------------------------------------

    when in doubt... do both things!
    Show Block cache hit ratio for requests where cacheBlocks=true
    --------------------------------------------------------------

    Key: HBASE-2253
    URL: https://issues.apache.org/jira/browse/HBASE-2253
    Project: Hadoop HBase
    Issue Type: Improvement
    Reporter: Dave Latham
    Priority: Minor

    We've been disabling block caching for MR jobs and other big scans. It seems to improve cache performance, but it's difficult to measure the hit ratio because even scans that don't cache blocks still request blocks from the cache (which is good), and those requests affect the hit/miss stats, which makes it difficult to see how the queries where cacheBlocks=true are performing.
    --
    This message is automatically generated by JIRA.
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    You can reply to this email to add a comment to the issue online.

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groupdev @
categorieshbase, hadoop
postedFeb 23, '10 at 7:49p
activeFeb 23, '10 at 8:19p
posts3
users1
websitehbase.apache.org

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ryan rawson (JIRA): 3 posts

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