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Date: Wed, 3 Feb 2010 04:53:18 +0000 (UTC)
From: "Catalina Wei (JIRA)" <jira@apache.org>
To: dev@openjpa.apache.org
Subject: [jira] Updated: (OPENJPA-1493) Performance improvement in
 SelectImpl.getTableIndex() for JPQL without subselect
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     [ https://issues.apache.org/jira/browse/OPENJPA-1493?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Catalina Wei updated OPENJPA-1493:
----------------------------------

          Description: 
OPENJPA-1185 introduced query context for table alias resolution that improved JPQL subquery processing.
However, JPQL queries without subselect pay  performance penalty because of the alias resolution by query context. In fact, if JPQL or QueryExpression do not contain subselect, then the table alias resolution can be simplified.
This can be done by checking if a SelectImpl is involved in a subquery:
If SelectImpl is not a subquery (it has no parent) or SelectImpl does not have any subselects, then the alias resolution by query context can be by-passed.

  was:
OPENJPA-1185 introduced query context that fixes JPQL subquery problems.
JPQL queries without subselect pay some performance penalty because of the alias resolution by query context
This can be avoided with a simple test which checks to see if the SelectImpl is involved in a subquery.
If SelectImpl is not a subquery (it has a parent) or SelectImpl does not have any subselects, then the alias resolution 
by query context can be by-passed.

    Affects Version/s: 2.1.0
                       2.0.1
                       2.0.0

> Performance improvement in SelectImpl.getTableIndex() for JPQL without subselect
> --------------------------------------------------------------------------------
>
>                 Key: OPENJPA-1493
>                 URL: https://issues.apache.org/jira/browse/OPENJPA-1493
>             Project: OpenJPA
>          Issue Type: Improvement
>          Components: query
>    Affects Versions: 2.0.0, 2.0.1, 2.1.0
>            Reporter: Catalina Wei
>            Assignee: Catalina Wei
>
> OPENJPA-1185 introduced query context for table alias resolution that improved JPQL subquery processing.
> However, JPQL queries without subselect pay  performance penalty because of the alias resolution by query context. In fact, if JPQL or QueryExpression do not contain subselect, then the table alias resolution can be simplified.
> This can be done by checking if a SelectImpl is involved in a subquery:
> If SelectImpl is not a subquery (it has no parent) or SelectImpl does not have any subselects, then the alias resolution by query context can be by-passed.

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