GitHub user DaveBirdsall opened a pull request:
https://github.com/apache/incubator-trafodion/pull/1044
[TRAFODION-2575] Truncate long strings when computing USTAT aggregates
This change affects the SELECTs that UPDATE STATISTICS generates when
computing aggregates on long character and varchar columns. We now truncate the
string before doing aggregation. (Note: We already do this in other code paths
in UPDATE STATISTICS -- namely internal sorts and sample table population. This
particular code path was overlooked.)
Besides improving performance, this will avoid UPDATE STATISTICS failing
due to lingering engine issues concerning long varchars and sorts.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/DaveBirdsall/incubator-trafodion Trafodion2575
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/incubator-trafodion/pull/1044.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #1044
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commit ca7c9c589eb01497ed7b24a83da812a75361999f
Author: Dave Birdsall <[email protected]>
Date: 2017-04-04T21:14:47Z
[TRAFODION-2575] Truncate long strings when computing USTAT aggregates
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