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https://issues.apache.org/jira/browse/HDFS-7174?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Kihwal Lee updated HDFS-7174:
-----------------------------
Description:
When the number of children under a directory grows very large, insertion
becomes very costly. E.g. creating 1M entries takes 10s of minutes. This is
because the complexity of an insertion is O\(n\). As the size of a list grows,
the overhead grows n^2. (integral of linear function). It also causes
allocations and copies of big arrays.
was:
When the number of children under a directory grows very large, insertion
becomes very costly. E.g. creating 1M entries takes 10s of minutes. This is
because the complexity of an insertion is O(n). As the size of a list grows,
the overhead grows n^2. (integral of linear function). It also causes
allocations and copies of big arrays.
> Support for more efficient large directories
> --------------------------------------------
>
> Key: HDFS-7174
> URL: https://issues.apache.org/jira/browse/HDFS-7174
> Project: Hadoop HDFS
> Issue Type: Improvement
> Reporter: Kihwal Lee
> Assignee: Kihwal Lee
> Priority: Critical
>
> When the number of children under a directory grows very large, insertion
> becomes very costly. E.g. creating 1M entries takes 10s of minutes. This is
> because the complexity of an insertion is O\(n\). As the size of a list
> grows, the overhead grows n^2. (integral of linear function). It also causes
> allocations and copies of big arrays.
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