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From "Fay Wang (JIRA)" <j...@apache.org>
Subject [jira] Updated: (OPENJPA-1493) Performance improvement in SelectImpl.getTableIndex() for JPQL without subselect
Date Thu, 04 Feb 2010 07:16:27 GMT

     [ https://issues.apache.org/jira/browse/OPENJPA-1493?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Fay Wang updated OPENJPA-1493:
------------------------------

    Attachment: OPENJPA-1493.patch

Internally OpenJPA will generate a subselect for NotContainsExpression in the where clause.
In this situation, the call to findAliasForQuery in the SelectImpl still must be made. 

> 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
>         Attachments: OPENJPA-1493.patch
>
>
> 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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