EntityQuery components hold the whole untruncated resultset if maxResults property is set
and the underlying dialect does not support limits
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Key: JBSEAM-2590
URL:
http://jira.jboss.com/jira/browse/JBSEAM-2590
Project: JBoss Seam
Issue Type: Bug
Components: Framework
Affects Versions: 2.0.1.GA
Reporter: vargadan
If the dialect supports limits then query objects only hold the number of rows set by the
maxResults property.
So i.e. if the search results 10000 rows but the page size is 10, only 10 objects are
kept.
But if the dialect does not support limits (like derby) then truncation of the result list
in done in EntityQuery.getResultList() which in the previous example results in the
following:
- 10000 objects are kept in EntityQuery.resultList
- only 10 of them is displayed in one page
- EntityQuery.getResultList() returns EntityQuery.resultList the sublist every time when
invoked
- when paginating the query is executed for every page, so there is no point in holding
all the rows.
It causes quite a big overhead when query components are kept in conversation scope, which
is the case most of the times.
If the truncation was done just after querying against the DB, there would not be such an
overhead.
I.e. Query.truncResultList gets invoked in EntityQuery.initResultList and
EntityQuery.resultList holds only the truncated list of results.
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