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https://issues.apache.org/jira/browse/DERBY-4116?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12688935#action_12688935
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Kathey Marsden commented on DERBY-4116:
---------------------------------------

Well just to see if this was a really easy fix, so I could continue my testing, 
I tried the trivial patch below:

--- java/engine/org/apache/derby/impl/sql/execute/AlterTableConstantAction.java 
(revision 757498)
+++ java/engine/org/apache/derby/impl/sql/execute/AlterTableConstantAction.java 
(working copy)
@@ -744,6 +744,7 @@
                                        rowBufferArray[GROUP_FETCH_SIZE - 1] = 
lastUniqueKey;
                                        lastUniqueKey = tmp;
                                } // while
+                               gsc.setEstimatedRowCount(numRows);
                        } // try
                        finally
                        {


but it doesn't affect my test case.  I verified that with this change the code 
goes through
OpenBTree.setEstimatedRowCount and sets the count to 4000, but there is this 
comment in OpenBTree.setEstimatedRowCount():

     * This call is currently only supported on Heap conglomerates, it
     * will throw an exception if called on btree conglomerates.
     *
It doesn't throw an exception, but it doesn't seem to do too much either. Any 
ideas what's wrong?


> SYSCS_UTIL.SYSCS_UPDATE_STATISTICS should update the store estimated row 
> count for the table
> --------------------------------------------------------------------------------------------
>
>                 Key: DERBY-4116
>                 URL: https://issues.apache.org/jira/browse/DERBY-4116
>             Project: Derby
>          Issue Type: Bug
>          Components: SQL
>    Affects Versions: 10.5.1.0, 10.6.0.0
>            Reporter: Kathey Marsden
>
> When SYSCS_UTIL.SYSCS_UPDATE_STATISTICS is run, it doesn't update the store 
> estimated row count.  The program oldSelectivity.java attached to DERBY-3955 
> shows that the statistics are not updated.
> See discussions in DERBY-3955
> https://issues.apache.org/jira/browse/DERBY-3955?focusedCommentId=12688789&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#action_12688789
> https://issues.apache.org/jira/browse/DERBY-3955?focusedCommentId=12688813&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#action_12688813

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