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https://issues.apache.org/jira/browse/DERBY-4422?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Dag H. Wanvik updated DERBY-4422:
---------------------------------
Urgency: Normal
Labels: derby_triage10_8 (was: )
> Extremely slow subqueries when subquerying on strings
> -----------------------------------------------------
>
> Key: DERBY-4422
> URL: https://issues.apache.org/jira/browse/DERBY-4422
> Project: Derby
> Issue Type: Bug
> Components: SQL
> Affects Versions: 10.5.3.0
> Environment: Suse Unix 10.3.
> Reporter: Tony Brusseau
> Labels: derby_triage10_8
> Attachments: SQLFile1.sqlaa.gz, SQLFile1.sqlab.gz, SQLFile2.sqlaa.gz,
> SQLFile2.sqlab.gz, SQLFile2.sqlac.gz, badqp.txt, derby.log,
> fixed-time-derby.log, goodqp.txt, tmp2.sql, unlimited-time-derby.log
>
>
> SELECT DISTINCT C.INTERNAL_ID
> FROM OC_CONCEPTS C
> WHERE
> (C.INTERNAL_ID IN (SELECT DISTINCT OCS.CONCEPT_ID FROM OC_CONCEPT_STRINGS
> OCS WHERE OCS.CONCEPT_ID=1))
> Both queries above are trivial and they are both acting on fully indexed
> primary key columns. This query runs just fine.
> However, when I make the small modification of searching on an indexed text
> column in the sub query, it takes over 6 seconds to run, even though both
> queries independently take < 1ms run.
> SELECT DISTINCT C.INTERNAL_ID
> FROM OC_CONCEPTS C
> WHERE
> (C.INTERNAL_ID IN (SELECT DISTINCT OCS.CONCEPT_ID FROM OC_CONCEPT_STRINGS
> OCS WHERE OCS.NL_LC = 'dash'))
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