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From Satheesh Bandaram <sathe...@Sourcery.Org>
Subject Re: [jira] Commented: (DERBY-649) Useful indexes not used in UNION ALL
Date Thu, 15 Dec 2005 15:08:05 GMT
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Thanks for reviewing the patch.<br>
<br>
Daniel John Debrunner wrote:<br>
<blockquote cite="mid43A12705.1080407@debrunners.com" type="cite">
  <pre wrap="">Satheesh Bandaram (JIRA) wrote:

  </pre>
  <blockquote type="cite">
    <pre wrap=""> 
I will also enhance this patch to make it more generic for trunk later.
    </pre>
  </blockquote>
  <pre wrap=""><!---->
When you say  &lt;ColumnReference&gt; &lt;RELOP&gt; &lt;constant&gt;,
can the constant be
a parameter?
  </pre>
</blockquote>
Yes, it can.<br>
<blockquote cite="mid43A12705.1080407@debrunners.com" type="cite">
  <pre wrap="">And closely related, in the code (UnionNode.java) you say
'For now, we only push simple
+	 * single column predicates that are binaryOperations.'

Does this need to be clarified? Maybe state explictly what can be pushed
down, maybe 'simple' to you, would be 'complex' to me?
  </pre>
</blockquote>
OK. I will expand the comments on this.<br>
<blockquote cite="mid43A12705.1080407@debrunners.com" type="cite">
  <pre wrap="">Could you explain new the code in pushExpressionsIntoSelect? Since you
have spent time on this, it would be great to capture your thoughts in
the code comments. For example, why do we need a new nodes that
represent '= TRUE', I'm sure it's required but to a reader of the code
it's not obvious why.
  </pre>
</blockquote>
OK. I will add more comments.<br>
<blockquote cite="mid43A12705.1080407@debrunners.com" type="cite">
  <pre wrap="">
Great patch to improve performance!
Dan.



  </pre>
</blockquote>
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