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https://issues.apache.org/jira/browse/DERBY-7173?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17913112#comment-17913112
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Bryan Pendleton commented on DERBY-7173:
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{quote}with two query clauses, almost all of the time is taken retrieving the
results
{quote}
I'm not sure I understand. Are you saying that the single-clause query and the
two-clause query return different result sets, and that's why their performance
is so different?
> Very poor performance with a = ? AND b = ? OR a = ? AND b = ? in query
> ----------------------------------------------------------------------
>
> Key: DERBY-7173
> URL: https://issues.apache.org/jira/browse/DERBY-7173
> Project: Derby
> Issue Type: Bug
> Components: SQL
> Affects Versions: 10.16.1.1
> Reporter: Richard Evans
> Priority: Major
> Attachments: lkp.java
>
>
> Execute a query like:
> SELECT * FROM table WHERE col1 = ? AND col2 = ? OR col1 = ? AND col2 = ?
> Performance is significantly worse then the simpler:
> SELECT * FROM table WHERE col1 = ? AND col2 = ?
> even though both col1 and col2 are indexed.
> Simple test case attached - run with db directory and number of OR clauses in
> query - use 2 for first example above and 1 for second.
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