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https://issues.apache.org/jira/browse/ACCUMULO-112?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Keith Turner updated ACCUMULO-112:
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Fix Version/s: 1.5.0
> Investigate partitioning in memory map by locality group
> --------------------------------------------------------
>
> Key: ACCUMULO-112
> URL: https://issues.apache.org/jira/browse/ACCUMULO-112
> Project: Accumulo
> Issue Type: Task
> Components: tserver
> Reporter: Keith Turner
> Assignee: Keith Turner
> Fix For: 1.5.0
>
>
> Currently the in memory map is not partitioned by locality group. This could
> negatively impact scan and minor compaction performance. Would like to run
> some experiments to understand the performance implications. Partitioning by
> locality group could negatively impact insert performance, it could go from
> O(log(R)+log(C)) to O(L * (log(R)+log(C))) in the worst case. L is the
> number of locality groups, R is the number of rows and C is the number of
> columns. The worst case is where each mutation has a change for each
> locality group.
> Currently the in memory map is a map of maps. Like the following.
> {noformat}
> map<row, map<col, val>>
> {noformat}
> Could conceptually change this to one of the following. The first is best
> for scans, that access some locality groups, and minor compactions. The
> second is good for inserts where the mutation covers all locality groups,
> because the row is only looked up once.
> {noformat}
> map<localityGroup, map<row, map<col, val>>>
> {noformat}
> {noformat}
> map<row, map<localityGroup, map<col, val>>>
> {noformat}
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