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https://issues.apache.org/jira/browse/TRAFODION-2282?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15612377#comment-15612377
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ASF GitHub Bot commented on TRAFODION-2282:
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GitHub user DaveBirdsall opened a pull request:
https://github.com/apache/incubator-trafodion/pull/792
[TRAFODION-2282] Update hive/TEST018 expected results, second attempt
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/DaveBirdsall/incubator-trafodion
Trafodion2282b
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/incubator-trafodion/pull/792.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 #792
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commit 0cc156df73eb366a68ee85de3b4c25f03d1bd32c
Author: Dave Birdsall <[email protected]>
Date: 2016-10-27T16:14:32Z
[TRAFODION-2282] Update hive/TEST018 expected results, second attempt
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> Optimizer histogram cache is sometimes never refreshed
> ------------------------------------------------------
>
> Key: TRAFODION-2282
> URL: https://issues.apache.org/jira/browse/TRAFODION-2282
> Project: Apache Trafodion
> Issue Type: Bug
> Components: sql-cmp
> Affects Versions: 2.1-incubating
> Environment: All
> Reporter: David Wayne Birdsall
> Assignee: David Wayne Birdsall
> Fix For: 2.1-incubating
>
>
> Here's the scenario:
> In session 1, create a table T1 and populate it with, say, 200000 or more
> rows.
> In session 2, prepare a query that selects from T1. For example, select
> A,COUNT(*) FROM T1 GROUP BY A. The query should compile fine, but you should
> see missing statistics warning messages (warning codes 6007 and 6008).
> In session 1, do "update statistics for table t1 on every column"
> In session 2, prepare other queries over a period of time. What should happen
> is that after about an hour, the Optimizer decides to refresh the histograms.
> However, due to a bug, it might never do so. So, the missing statistics
> warnings (6007, 6008) never go away. Worse, the prepares never benefit from
> the statistics so plan choice may be poor.
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