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From Tarun Dogra <Tarun.Do...@orioncro.com>
Subject FW: Jackrabbits reliability and performance
Date Thu, 14 Nov 2013 16:21:22 GMT
Hi Enrique,

Thanks for the detailed reply. Unfortunately, I am not familiarised with the nodes and the
BTree side of Jackrabbit framework. So I was expecting an answer in terms of the overall picture
of how Jackrabbit as a JCR will fit in to our system.

In brief, we need to integrate Jackrabbit (as advised by our vendor) in to our clinical trial
management system. For this, I have already provided you with the server specification on
which the system will be hosted. So just wanted to know if on such server, Jackrabbit is capable
enough to intake approximately 15GB data per year and be able to manage those many documents/files
(as mentioned before) without being affected in terms of its performance? We already know
it is a much stabilised JCR, but we just wanted to confirm if such system is able to suffice
our organisation’s requirements.

Regards,
Tarun


From: Enrique Medina Montenegro [mailto:e.medina.m@gmail.com]
Sent: 14 November 2013 14:29
To: users@jackrabbit.apache.org<mailto:users@jackrabbit.apache.org>
Cc: Mark Essex
Subject: Re: Jackrabbits reliability and performance

Hi Tarun,

Let me share my findings with you :-)

At my work we are evaluating the use of Jackrabbit to build a JCR repository to store the
register of marks (intellectual property) as documents composed basically of an ID, some metadata
(who created it, when, etc.) and the XML and JSON representation of the mark itself. Currently,
we have all that information spread in several relational DBs and we would like to take advantage
of the versioning and observation features of the JCR repository.

During our initial evaluation, mostly focused on performance, we noticed serious issues when
adding the 1 million marks we have currently in our DBs underneath the same "parent" node,
but we found out that this was actually a known limitation by Jackrabbit, which clearly states
that no more than 10K child nodes should be added to the same "parent "node:

http://wiki.apache.org/jackrabbit/Performance

However, we were still sort of forced to follow that path because we were required to perform
an initial dump of all the data in the DBs, and just adding each mark as a sub-mode proved
to be the fastest way to export all the data in an acceptable window frame.

Nevertheless, we also tried to shard the nodes as a tree, basically splitting the 9-digit
ID of our marks into 3-digit groups, so each node could only have as much as 1K sub-nodes
within itself. For example, mark with ID = 000342865 would be saved into --> root (node)
-> marks (node) -> 000 (node) -> 342 (node) --> 000342865 (node). Theoretically,
this would perform much better than our original approach, but as a downside, it would dramatically
slow down the time it takes to export the 1M marks from the DBs, going further out of our
acceptable window frame (due to the fact that, for each mark, it had to previously look up
the exact node where to store it, and the bigger the JCR repository was growing, the slower
the node lookup times were, therefore impacting the overall export process).

We also took a look at the BTreeManager, but we just couldn't make it work due to the issue
I describe here (which BTW has not been answered yet):

http://mail-archives.apache.org/mod_mbox/jackrabbit-users/201311.mbox/ajax/%3CCA%2BdeSP_weUQ0mtSBjoQGy3jq60jZEo7LtmF9kJZkvF1eyNvu-A%40mail.gmail.com%3E

So getting back to the original approach of storing everything under the same node, how did
we manage to get acceptable read times? Well, it boils down to using Lucene's indexation (configured
properly to only index the "id" property, and not all the XML and JSON stuff - using the IndexingConfiguration
in the Search section of the repository config file) to actually perform the search/retrieval
of marks. So for instance, instead of:

session.getNode("/marks/000342865") --> takes ~2.4segs with 1M marks under the same node

we run this query with SQL2:

SELECT * FROM markType WHERE id = '000342865' --> takes tens of ms with 1M marks under
the same node thanks to Lucene's indexes

(notice that "markType" is a custom node type that we have created to model our domain, in
this case the marks)

LESSONS LEARNED: You need to clearly define the scope of your project in terms of the functionality
you're willing to use from Jackrabbit, and then plan for detailed performance workshops to
prove your approach. There are always trade-offs (for instance, in my case, when I want to
get the specific version of a mark, I cannot use the "official" API through "VersionManager"
because it uses direct path to fetch the node prior to getting the revision --> session.getWorkspace().getVersionManager().getVersionHistory("/marks/000342865").getVersionByLabel("v.6.0"),
and I have to use the "deprecated" API method from the node itself, once I've got it using
the SQL2 statement mentioned above --> markNode.getVersionHistory().getVersionByLabel("v.6.0"),
with the uncertainty on when that deprecated API will be removed...).

Please share your findings in the list as you make progress :-)

Regards,
Enrique Medina.

On Thu, Nov 14, 2013 at 10:40 AM, Tarun Dogra <Tarun.Dogra@orioncro.com<mailto:Tarun.Dogra@orioncro.com>>
wrote:
Respected Sir/Madam,

In the next couple of months, we (ORION Clinical Services Ltd., UK) are about to release a
clinical trial management system as a product to be used in-house by all our employees. We
have bought this product off the shelf from a third party vendor. As suggested by our vendor,
we would implement JackRabbit as the central repository system within this main product. But
we are still not sure whether jackrabbit is an ideal solution to be integrated with our product
and this is where we will need your help and would appreciate if you could share your expertise.

Just to give you an overview of our organisation, we will have around 7500 documents (each
of size 250K approximately on an average) per "study" within our clinical trial management
framework. We usually take on board  around 7-8 such studies per year. So, on the basis of
8 studies per year, the total size of all the documents will grow to 7500 x 250 x 8 = 15GB
approximately per year. So just wanted to know a couple of things from you:

1.       Is Jackrabbit reliable enough as a system to cater to our above mentioned needs?
and

2.       Will the management of so many documents have any adverse effects on jackrabbit's
performance? - considering that Jackrabbit will reside on one of our own hosted server with
the following spec -

Poweredge R710

CPU: 2 x Intel X5550

Memory: 16GB

Operating System: Windows 2008 R2 64bit SP1

Disk capacity: C: 142gb and D: 1.22Tb


Sorry if you are not the correct department to consult to in regards to our above mentioned
concern and if this is the case, it will be much appreciated if you could direct us to the
right department/person? Many thanks.

Look forward to hearing from you.

Regards,
Tarun

________________________________
**********************************Legal & Confidentiality Notice**************************************
This email and attachments hereto are strictly private and confidential. Reading, copying,
disclosure or use by anybody else is not authorised. If you have received this email in error,
please delete it and notify us as soon as possible.
The antivirus software used by ORION is automatically and constantly updated in an effort
to minimise the risk of viruses infecting our systems, However, you should be aware that there
is no absolute guarantee that any files attached to this email are virus free.
ORION may monitor email traffic data and also the content of email for the purposes of security
and staff training.
ORION Clinical Services Limited is a private limited company registered in England. Company
number 3457136. Registered address: 7 Bath Road, Slough, Berkshire, SL1 3UA. ORION Clinical
Services Limited is the parent company of a number of subsidiary companies. For further details
please visit our website at www.orioncro.com<http://www.orioncro.com>
________________________________________


________________________________
**********************************Legal & Confidentiality Notice**************************************
This email and attachments hereto are strictly private and confidential. Reading, copying,
disclosure or use by anybody else is not authorised. If you have received this email in error,
please delete it and notify us as soon as possible.
The antivirus software used by ORION is automatically and constantly updated in an effort
to minimise the risk of viruses infecting our systems, However, you should be aware that there
is no absolute guarantee that any files attached to this email are virus free.
ORION may monitor email traffic data and also the content of email for the purposes of security
and staff training.
ORION Clinical Services Limited is a private limited company registered in England. Company
number 3457136. Registered address: 7 Bath Road, Slough, Berkshire, SL1 3UA. ORION Clinical
Services Limited is the parent company of a number of subsidiary companies. For further details
please visit our website at www.orioncro.com
________________________________________

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