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  1. Phoenix
  2. PHOENIX-6334

All map tasks should operate on the same restored snapshot

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    Details

    • Type: Bug
    • Status: Open
    • Priority: Major
    • Resolution: Unresolved
    • Affects Version/s: 5.0.0, 4.14.3
    • Fix Version/s: None
    • Component/s: core
    • Labels:
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      Description

      Recently we switched an MR application from scanning live tables to scanning snapshots (PHOENIX-3744). We ran into a severe performance issue, which turned out to a correctness issue due to over-lapping scan splits generation. After some debugging we figured that it has been fixed via PHOENIX-4997. 

      We also need not restore the snapshot per map task. The purpose of this Jira is to correct that behavior. Currently, we restore the snapshot once per map task into a temp directory. For large tables on big clusters, this creates a storm of NN RPCs. We can do this once per job and let all the map tasks operate on the same restored snapshot. HBase already did this via HBASE-18806, we can do something similar.

       

      All other performance suggestions here: https://issues.apache.org/jira/browse/PHOENIX-6081

       

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            • Assignee:
              shahrs87 Rushabh Shah
              Reporter:
              saksham.gangwar Saksham Gangwar
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              • Created:
                Updated: