[jira] [Closed] (TRAFODION-2376) Improve UPDATE STATISTICS performance for varchar columns

["liu ming (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/TRAFODION-2376?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

liu ming closed TRAFODION-2376.
-------------------------------
    Resolution: Fixed

> Improve UPDATE STATISTICS performance for varchar columns
> ---------------------------------------------------------
>
>                 Key: TRAFODION-2376
>                 URL: https://issues.apache.org/jira/browse/TRAFODION-2376
>             Project: Apache Trafodion
>          Issue Type: New Feature
>          Components: sql-cmp
>    Affects Versions: 2.1-incubating
>         Environment: All
>            Reporter: David Wayne Birdsall
>            Assignee: David Wayne Birdsall
>             Fix For: 2.2-incubating
>
>
> Today when UPDATE STATISTICS uses internal sort, varchar columns are expanded out to their maximum length with blank padding. This can be quite wasteful both of memory and CPU cycles, as often the average length of a varchar is much less (even orders of magnitude less) than the maximum length. We can do much better performance wise by not doing this expansion, at the cost of some complexity in comparison.



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