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[protege-discussion] Performance problems opening ontology in multi-user mode with ChAO

Ulf Licht Ulf.Licht at
Thu Oct 4 08:42:43 PDT 2012

Hello list,

we recently started to use the Change and Annotation Ontology (ChAO) with 
our Protege multi-user installation. It worked fine for a while but now we 
see serious performance degradation. The ChAO is persisted in an Oracle 
database and the table current contains about 195.000 entries after using 
it for a few weeks. Currently opening a project with an attached ChAO is 
impacted the most (up to 70 minutes). The client log file indicates that 
opening the ChAO for the project takes the longest time. We did some 
further analysis and found that a server job called 
"GetSortedTopLevelChangesJob", which is started by the Changes Tab of an 
Protege client, issues many individual prepared database statements, which 
take a lot of time to complete. We created additional indexes to mitigate 
the problem and brought the time for opening a project to about 20 
minutes, which is still not acceptable.

Did anyone experience similar performance problems while using the ChAO 
and has any idea how to improve it? Archiving the ChAO every few weeks is 
not an option since we would have to search for changes over many archived 
ChAOs. An archive interval of once a year would be acceptable. How do 
others handle archiving of ChAO information?

Best regards,

Esprit Europe GmbH
40882 Ratingen

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