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From "Josh Elser (JIRA)" <j...@apache.org>
Subject [jira] [Created] (ACCUMULO-2932) Increased control over write durability
Date Fri, 20 Jun 2014 16:40:26 GMT
Josh Elser created ACCUMULO-2932:
------------------------------------

             Summary: Increased control over write durability
                 Key: ACCUMULO-2932
                 URL: https://issues.apache.org/jira/browse/ACCUMULO-2932
             Project: Accumulo
          Issue Type: Improvement
          Components: tserver
            Reporter: Josh Elser


ACCUMULO-2842 introduced the ability to configure the HDFS method that is use to sync WALs.
This was mainly done as a means to investigate the performance characteristic of hflush and
hsync. As such, it was was trivially done system-wide.

However, there is also practical application to allowing this configuration, in addition to
some internal concerns.

# We should *always* sync WALs involved in {{accumulo.metadata}}
# Data loss may be acceptable on some user tables and not on others (we may want to use hflush
for some tables, hsync for other). The option must have the granularity to specify at least
on the table (if not locality group).

When multiple tablets are using a WAL with differing durability guarantees, we should choose
the higher durability.

If we compare this to HBase, we could also implement it on the per Mutation level, however
that's beyond the scope here.



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