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From "Todd Pagni (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (JCR-3537) Large number of SQL queries when adding nodes with version history
Date Fri, 22 Mar 2013 01:11:15 GMT

    [ https://issues.apache.org/jira/browse/JCR-3537?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13609768#comment-13609768
] 

Todd Pagni commented on JCR-3537:
---------------------------------

I am adding a single file with a resource node that contains the file content and a few properties.
 There is only one file in the parent folder.   When the version is created on file check
in, 100's of select statements are executed while storing the parent / child version.  The
patch is attempting to reduce the # of queries being executed, but I am not why 100's of queries
are being executed when adding an single file to a folder.  There are not that many actual
child nodes, so am not sure what the childNodeEntries represent in the version code that is
causing the select queries  (see below). 

NodeSateEx.store(NodeState) around line 739 you will find the following: 

// now store all child node entries
for (ChildNodeEntry entry : state.getChildNodeEntries()) {  //this collection has 100's of
items, not sure why.  
  NodeState nstate = (NodeState) stateMgr.getItemState(entry.getId());  //causing select queries


Any help you can provide on this topic is appreciated.  If we cannot improve performance on
saving versions, it does not bode well for the future of jackrabbit in our product.  
                
> 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
>
>
> 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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