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https://issues.apache.org/jira/browse/JCR-3537?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13622435#comment-13622435
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Marcel Reutegger commented on JCR-3537:
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Thanks for the test and the instructions. This is very helpful.
The child nodes in question are part of the version storage content structure.
E.g. a version history node may have a path like this:
{{/jcr:system/jcr:versionStorage/40/ed/38/40ed38c9-cb13-41dc-8602-0249e2c1b4c2}}
Now, whenever a new versionable node is created, a new version history is
created and it may happen that a new intermediate node must be created. Todd
identified this already in {{InternalVersionManagerBase#getParentNode}}. With
the current implementation and the recursive behavior also all siblings of the
added node are checked whether they are modified. This may lead to up to 255
additional calls, until all intermediate nodes are present (from '00' to 'ff'
on the three levels).
The provided patch looks good and IMO addressed the problem correctly. There
may be other cases where the recursive call is unnecessary, but we can address
those also later.
> Large number of SQL queries when adding nodes with version history
> ------------------------------------------------------------------
>
> Key: JCR-3537
> URL: https://issues.apache.org/jira/browse/JCR-3537
> Project: Jackrabbit Content Repository
> Issue Type: Bug
> Components: versioning
> Affects Versions: 2.5
> Environment: Windows 2008, tomcat application server, SQL Server 2008
> database server
> Reporter: Todd Pagni
> Labels: newbie, patch
> Attachments: jackrabbit-core-2.5.0-version-history.patch,
> jackrabbit-debug.rar
>
>
> We are adding a large number of documents to a jackrabbit 2.5 database
> repository. We are using the bundle.MSSqlPersistenceManager and we are
> seeing a large number of SQL queries (300+) when adding a single folder,
> file, and file content. This appears to create a significant performance
> bottleneck when adding documents when the repository size is over 300k
> documents/nodes. The repository structure is a hierarchy with less than 1000k
> child nodes per parent. The following is an example structure of the repo
> with the (New child folder) representing the new content being added.
> -- Root node
> -- Parent node
> --New child folder (mix:versionable,mix:lockable)
> --new file (mix:versionable,mix:lockable)
> --new document content
> --Existing Child Folder
> -- Parent node
> The vast majority of the 200-300+ queries that execute when adding a node
> look like the following:
> exec sp_execute 2,0x5740D9A36F2E4032BFF0BA652D89FFB8
> exec sp_execute 2,0xBBFE059BF7E44947A8B0858F3CE33DB8
> exec sp_execute 2,0xC2AD22DBE1DB43A083BCA1B2C94E07CC
> The majority of the queries that are executed appear to be related to
> versioning. When a node is added the version history for the node
> stored/saved, the parent node is saved, which ultimately cascades and saves
> all children of the parent, so adding a child node saves the parent and all
> other children.
> We have created a patch for jackrabbit-core 2.5.0 to prevent the cascade to
> store all other child nodes when saving/storing the version history of a new
> node. This cuts the number of queries that are executed in half. Does
> anyone see a problem with this technique? All unit tests are still passing.
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