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From "Mark Waschkowski" <mwaschkow...@gmail.com>
Subject Re: Jackrabbit = Kick Ass Tool (was: Jackrabbit = Big Trouble??)
Date Tue, 07 Aug 2007 15:45:47 GMT
Hi David,

I would like to update the wiki with the below information, as I think its
quite valuable and would help new users without having to scour the mailing
list. If you verify the following, I will update the wiki.

-----For wiki:
Using DBFileSystem as specified in the repository.xml:
<Repository>
        <FileSystem ...>

and using the same database any of the PersistenceManager entries, the only
things that need to be backed up are:
1) repository.xml
2) the database

Then, to restore from a backup, all that would need to be done is to use the
backed up repository.xml, restore the database using the backup, and the
indexes will rebuild themselves when the system restarts. This will properly
handle versioning as well.

Note: rebuilding of indexes may take a significant amount of time
----end

If all that looks correct, I'll fill in an example FileSystem and update the
wiki. As well, any suggestions for the 'significant amount of time part'?

Thanks,

Mark

On 7/30/07, David Nuescheler <david@day.com> wrote:
>
> Hi Bruce,
>
> thanks for your comment.
>
> > I am not fired by index problems. -)
> > I just want to everybody realize it is very critical issue to back up
> your repository.
> > Currently, the solution is:
> > 1) Backup DB data.
> > 2) Backup your file system and you can delete all indexes of them.
> > However, it is still a bug that JackRabbit v1.3 can not rebuild
> everything from DB, in
> > case your hard driver dies with all your repository file system.
> Shouldn't that be solved by the DBFileSystem.
> http://yukatan.fi/2007/1.4/org/apache/jackrabbit/core/fs/db/DbFileSystem.html
>
>
> This allows you to store everything that is necessary for a complete
> restore
> in the DB, which means your DB backup is the only thing (beyond the
> repository.xml) that you need to restore a complete JR instance.
>
> > My concerns are two:
> > 1) Performance of navigation of Nodes which relates cache manager
> resizing
> I appreciate the performance issue. I am still not convinced that this
> is related
> with the cache manager resizing...
>
> > 2) Logic backup repository using JCR export/import API.
> I agree that it would be desirable to have a built-in backup/restore
> mechanism on a higher level.
>
> The JCR export/import is probably not the right layer,
> since it only covers the content in a single workspace and has no
> means to address things like nodetypes, versions or the
> namespace registry.
> And I think your most pressing issue should be addressed
> by the DBFileSystem.
>
> regards,
> david
>
> > -----Original Message-----
> > From: bdelacretaz@gmail.com [mailto:bdelacretaz@gmail.com] On Behalf Of
> Bertrand Delacretaz
> > Sent: Friday, July 27, 2007 3:15 AM
> > To: users@jackrabbit.apache.org
> > Subject: Jackrabbit = Kick Ass Tool (was: Jackrabbit = Big Trouble??)
> >
> > Hi,
> >
> > I hate to play grumpy old man once again, but the recent trend towards
> > Loud Subjects That Catch Peoples Attention does not really help the
> > discussion, so let's rename this thread ;-)
> >
> > Bruce, if I read your message correctly, it looks like you have three
> > problems with Jackrabbit:
> >
> > 1) Cache Manager resizes seem to slow your app down
> > 2) You're going to be fired because you lost your index (or Jackrabbit
> did)
> > 3) You're not sure about which application pattern/content model to use
> >
> > So let's please tackle these one at a time, ideally in separate
> > threads so that people can contribute efficiently to the discussion.
> >
> > Sorry if I'm being a bit harsh, but IMHO you started it with the
> > choice of your message's subject ;-)
> > -Bertrand
> >
> >
> > On 7/27/07, Bruce Li < bli@tirawireless.com> wrote:
> > > I have been in this Jackrabbit Community for a couple of months since
> I joined repository project two months ago.
> > >
> > >
> > >
> > > First, I respect and appreciate all hard works contributed in current
> JackRabbit project and definitely I am sure a lot of developers benefit from
> this project. There are some people contribute their JackRabbit working
> experience like David Nuescheler, who collects "7 DR Rules", which is
> precious since current lack of document of JackRabbit, and they are "real"
> working experiences.
> > >
> > >
> > >
> > > However, I also heard some negative voice from this community like
> "JackRabbit is dead (for us)" from Frédéric Esnault. I suffer some troubles
> from JackRabbit and it seems foundational problems. I would like to share
> all my experience with you, and any feedback or good suggestion is
> definitely what I want.
> > >
> > >
> > >
> > > Since these troubles are "big" troubles for enterprise use of
> JackRabbit 1.3, let's discuss it from beginning.
> > >
> > >
> > >
> > > Question 1:
> > >
> > > Why do you select JackRabbit rather than Database as your repository
> solution?
> > >
> > >
> > >
> > > There are a lot of answers for this question and it seems that
> everybody who joins this community has already known the answers (It may be
> formal document which was approved by your CTO).  However, my opinion, this
> is the basic question really need to be discussed here.
> > >
> > >
> > >
> > > To answer this question, some technical key words to support
> Jackrabbit may be "JCR API", "Lucene Search Engine" and so on. However, as
> the user of JackRabbit, I would like to list the two key concerns why I
> select JackRabbit as repository solution from Product Point of View:
> > >
> > >
> > >
> > > 1.      Quick and effective data search/fetch from volume content
> repository
> > > 2.      Build-in content version/revision control without extra code
> > >
> > >
> > >
> > > Now let me describe the big troubles I met in my use:
> > >
> > > 1.      Quick and effective data search or fetch from volume content
> repository
> > >
> > >
> > >
> > > Experience: There are not many data on my repository which contains
> hundreds of two major object nodes, each node (object) contains less than 20
> properties (fields), including the other 5 child nodes (nested small
> objects) and one of two major nodes(object) has one binary data (up to 1
> megabyte). Unfortunately, the performance is not acceptable when I navigate
> nodes of the major nodes. The main problem is the build-in Cache Manager of
> JackRabbit resizes which costs uncertain time, which result the operation
> very slow sometimes.  It is not easy to read those codes when debugging
> Jackrabbit for performance tuning because there is no document about the
> logic behind the index resizing.
> > >
> > >
> > >
> > > 2.      Content version/revision control
> > >
> > > Experience: This function works well on Jackrabbit v1.3. The main
> problem is that all revision (except base revision) of node are lost when
> export/import data from one repository to another repository. I am
> discussing this issue because it concerns the repository backup.
> > >
> > >
> > >
> > > I just found in JackRabbit v1.3, there is no way to backup repository
> using DB as persistence manager. I mean that there is no way to re-index
> based on data on DB. The following is my case:
> > >
> > >
> > >
> > > In one repository server, the index (in file system) is corrupt which
> causes all search failure. However, all data (in DB) is still alive, where
> you can iterate all of them. After clean the whole repository file system
> (most of them are index information), Jackrabbit can not correctly re-build
> index based on the data on DB. If it happens on production repository, it
> means: "My God, I am going to be fired". As I know, Jackrabbit v1.1 can
> successfully re-index (creating totally new repository index (file system)
> based on DB data).
> > >
> > >
> > >
> > > As the alternative solution to backup repository, I try to
> export/import all nodes from repository to another repository using JCR
> Export API (exportSystemView). The good news is that JackRabbot v1.3successfully builds
index (the whole file system) during the importing
> process; the bad news is that it lost all revision of all versioning nodes.
> Can you image how frustrate I am when I realize there is no way to backup
> repository based on DB data?
> > >
> > >
> > >
> > > I just got the answer for the re-index issue for Jackrabbit v1.3: You
> CAN NOT delete all file system. Only delete all indexes but keep the other
> folders. Jackrabbit can re-index successfully when it starts up.
> > >
> > >
> > >
> > > Question 2:
> > >
> > > How can developer correctly use Jackrabbit (JCR) as their repository
> solution?
> > >
> > >
> > >
> > > The expert of jackrabbit may see that I use object to describe node
> and you may think it is not the pattern you are using Jackrabbit. So the
> question is raised as "Which is the best practices (pattern) to use
> Jackrabbit (JCR) as repository solution."
> > >
> > >
> > >
> > > From this community, I see a lot of developers use Jackrabbit by
> fetching contents by path. It means that they do not need treat node as
> object, instead, they put content on repository as asset, which can be
> easily and effectively retrieved by a given path. This pattern exactly meets
> the truth of "The simplicity is the best".
> > >
> > >
> > >
> > > My use of Jackrabbit is based on the business requirement, which need
> to navigate most of nodes and reference nodes, check child nodes and
> properties to find the proper content by a couple of business rules. I would
> like to say that all performance issues are raised by nodes iteration
> process. Even more, I have created generic classes using java reflect
> package for bi-directory mapping between nodes and objects. For performance
> improvement, the mapping supports generic child nodes lazy loading. However,
> it seems all these jobs do not solve the performance problem although they
> sound pretty "professional".  You may ask me: if you have such business
> requirement, why not go to DB and build the full relationship for your
> business model? J2EE developers all know how powerful java-db world is: the
> mature ORM tool ( e.g. Hibernate), transaction management, batch data
> fetching, performance tuning and so on. However, my question is: "Is there
> any good pattern in current jackrabbit to effectively handle data fetching
> with week relationship?"
> > >
> > >
> > >
> > > Now it is time to say some words to the jackrabbit developers and
> contributors what I really want to say for the whole community:
> > >
> > >
> > >
> > > My begs:
> > >
> > > Guide, document and sample code is the king for any open source. How
> frustrating for Jackrabbit developers find the incorrect pattern is applied
> by users on their projects. On the other hand, how frustrating for
> JackRabbit users can not find the good pattern to follow, which can save
> their bunch of time. From product point of view, the search by XPath or
> XQuery or SQL is not foundational issue. The foundational issue is one
> effective search means covers most of important requirements from real world
> and the document can be found in jackrabbit web site.
> > >
> > >
> > >
> > >
> > >
> > > I do believe Jackrabbit is qualified project and I really hope all
> "best features" are documented, demoed and used by the whole community.
> > >
> > >
> > >
> > > Thanks
> > >
> > >
> > >
> > > Bruce
> >
>



-- 
Best,

Mark Waschkowski

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