[jira] Created: (HBASE-2468) Improvements to prewarm META cache on clients

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

Improvements to prewarm META cache on clients
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                 Key: HBASE-2468
                 URL: https://issues.apache.org/jira/browse/HBASE-2468
             Project: Hadoop HBase
          Issue Type: Improvement
          Components: client
            Reporter: Todd Lipcon
             Fix For: 0.20.5


A couple different use cases cause storms of reads to META during startup. For example, a large MR job will cause each map task to hit meta since it starts with an empty cache.

A couple possible improvements have been proposed:
 - MR jobs could ship a copy of META for the table in the DistributedCache
 - Clients could prewarm cache by doing a large scan of all the meta for the table instead of random reads for each miss
 - Each miss could fetch ahead some number of rows in META


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