[
https://issues.apache.org/jira/browse/OLINGO-1183?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16641761#comment-16641761
]
Patrick Haller commented on OLINGO-1183:
----------------------------------------
*Analysis*
If using the paging with $top, $skip and $inlinecount=allpages the class
JPAPage load all entities ...
* *JPAProcessorImpl.handlePaging( Query, GetEntitySetUriInfo )* is only
setting query.setFirstResult() and query.setMaxResult() if no $inlinecount is
present at all. Hence if an $inlinecount is present, it potentially reads
hundreds of thousands of entities into memory. This has massive impact on
database performance and JVM memory consumption.
* *ODataJPAResponseBuilderDefault.getInlineCountForNonFilterQueryEntitySet()*
is using that non-paged list of all entities of a query to determine the count.
Only after that, the returned result is reduced to page size.
This is a quite inefficient way to count entities. This inefficiency is
unexpected to calling clients and, even if it was, cannot always be
circumvented.
A proposal would be that the JPAProcessorImpl is actually issuing a 2^nd^
database call during GetEntitySet in conjunction with $inlinecount to just
count the entities, without reading them.
> JPAPage - Load all entities from DB, no paging on DB query
> ----------------------------------------------------------
>
> Key: OLINGO-1183
> URL: https://issues.apache.org/jira/browse/OLINGO-1183
> Project: Olingo
> Issue Type: Bug
> Components: odata2-jpa
> Affects Versions: V2 2.0.8, V2 2.0.9
> Reporter: Francesco longhitano
> Priority: Major
>
> If i using the paging with $top, $skip and $inlinecount=allpages the class
> JPAPage load all entities from DB (howewer filtered by the where), no setting
> on top and skip for paginated query directly from db. That's a problem if the
> query return many result (in our case ~100000 of complex entity).
> I'm looking into the code and the problem is not so easy to resolve. The
> inlinecount is managed by ODataJPAResponseBuilderDefault, as an size() called
> on the result of query. Then if there is top or skip the class do a filter on
> the result list, to return to client only the correct entities. So even if i
> correct set top and skip on JPAPage modifing the method handlePaging using an
> custom implementation of JPAProcessor, then the result __count show an wrong
> result.
> Example URL
> Entities?$skip=10&$top=10&$inlinecount=allpages
--
This message was sent by Atlassian JIRA
(v7.6.3#76005)
