[jira] [Updated] (HBASE-1938) Make in-memory table scanning faster

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

     [ https://issues.apache.org/jira/browse/HBASE-1938?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

nkeywal updated HBASE-1938:
---------------------------

    Attachment: 20110802_MemStore.patch
                MemStoreScanPerformance.java

Test added to show the impact when the snapshot is not empty.

Patch on MemStore.java, to optimize the "peek()" function by precalculating the next value. Improve the performances by 25% on the test above (i.e. when the two lists are not empty), by saving a call on the comparator.

"reseek" is now synchronized, + minor modifications (@overide added, private added, ...).

> Make in-memory table scanning faster
> ------------------------------------
>
>                 Key: HBASE-1938
>                 URL: https://issues.apache.org/jira/browse/HBASE-1938
>             Project: HBase
>          Issue Type: Improvement
>          Components: performance
>            Reporter: stack
>            Assignee: nkeywal
>            Priority: Blocker
>             Fix For: 0.90.4, 0.92.0
>
>         Attachments: 20110726_1938_KeyValueSkipListSet.patch, 20110726_1938_MemStore.patch, 20110726_1938_MemStoreScanPerformance.java, 20110802_MemStore.patch, MemStoreScanPerformance.java, MemStoreScanPerformance.java, MemStoreScanPerformance.java, caching-keylength-in-kv.patch, test.patch
>
>
> This issue is about profiling hbase to see if I can make hbase scans run faster when all is up in memory.  Talking to some users, they are seeing about 1/4 million rows a second.  It should be able to go faster than this (Scanning an array of objects, they can do about 4-5x this).

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