Documentum on PostgreSQL

September 17, 2013 at 3:53 pm | Posted in Performance | Leave a comment
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Great news from Lee Dallas reporting from the Documentum Developer Conference: Documentum Developer Edition is back and now runs on PostgreSQL. I discussed this a few months back and I thought that maybe EMC didn’t have the stomach for something so technical, but I was wrong. So kudos to EMC.

Lee mentions it’s not yet production ready, so hopefully that is in the pipeline. After that how about certifying it to run on Greenplum, EMC’s massively scalable PostgreSQL. Then the sky is the limit for large-scale NLP and machine learning tasks. For example last year I wanted to run a classification algorithm on document content to identify certain types of document that couldn’t be found by metadata. There are plenty of other uses I can think. 

I’ll be downloading the edition as soon as possible to see how it runs.

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Documentum and Databases

July 3, 2013 at 4:11 pm | Posted in Performance | 4 Comments
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Here’s a quick thought on Documentum and databases. For a long time Documentum used to support a variety of databases however these days support is just for 2 in D7 (Oracle and SQL Server) down from 4 in D6.7 (the previous 2 plus DB2 and Sybase).

The clear reason for narrowing down the choice of database server is (I suspect) the cost of developing for and supporting a large number of choices, particularly since most of the database/OS combinations were used by only a handful of customers.

So why doesn’t EMC port the application to postgres and cut that choice down to 1? Why postgres? Well because EMC owns Greenplum (well actually it’s now part of Pivotal but that just complicates the story) and Greenplum is an enhanced postgres.

The logic for this is clear: EMC would like people to move to OnDemand and it makes sense for them to have ownership of the whole technical stack. At the very least they must be shelling out money to one of the database vendors. I’m not sure which one – if you have access to an OnDemand installation try running ‘select r_server_version from dm_server_config’ and see what’s returned, someone let me know the results if you could.

There are a couple of reasons why EMC might be reluctant. First it’s a big change and people (including EMCs own development and support teams) have a big skills base in the legacy databases. Taking a medium-term strategic view this is not a great reason and is just a product of FUD – Documentum has taken brave technical steps in the past such as eliminating the dmcl layer with great success.

Second we’ve been hearing a lot over the last few years about the NG server that runs on XHive xml database that is touted to replace the venerable Content Server in the longer term. Perhaps EMC is reluctant to work on 2 such radical changes.

Who knows? It’s just a thought …

 

Taking the EMC Data Science associate certification

May 13, 2013 at 10:06 am | Posted in Big Data, Performance | 12 Comments
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In the last couple of weeks I’ve been studying for the EMC data science certification. There are a number of ways of studying for this certificate but I chose the virtual learning option,which comes as a DVD that installs on a Windows PC (yes Macs are no good!).

The course consists of six modules and is derived from the classroom-based delivery of the course. Each module is dedicated to a particular aspect of data science and big data with each following a similar pattern: a number of video lectures and followed by a set of lab exercises. There are also occasional short interviews with professional data scientists focusing on various topical areas. At the end of each module there is a question and answer multiple-choice to test your understanding of the subjects.

The video lectures are a recording of the course delivered to some EMC employees. This has some pros and cons. Occasionally we veer off from the lecture to a group discussion. Sometimes this is enlightening and provides a counterpoint to the formal material, however sometimes microphones are switched off or the conversation becomes confused and off-topic (just like real life!). Overall this worked pretty well and make if easier to watch.

The labs are more problematic. You get the same labs as delivered in the classroom course however you simply get to watch a camtasia studio recording of the lab with a voiceover by one of the presenters. Clearly the main benefits of labs is to enable people to experience the software hands-on, an essential part of learning practical skills. Most of the labs use either the open source R software or EMCs own Greenplum which is available as a community software download. There is nothing to stop you from downloading your own copies of these pieces of software and in fact that is what I did with R. However many of the labs assume there are certain sets of data available on the system; in some cases this is CSV files which are actually provided with the course. However relational tables used in Greenplum are not provided. It would have been nice if a dump of the relational tables had been provided on the DVD. A more ambitious idea would have been to provide some sort of online virtual machine in which subscribers to the course could run the labs.

Since the lab guide was provided I was able in many cases to follow the labs exactly, where the data was provided, or something close to it by generating my own data. I also used an existing Postgres database as a substitute for some of the Greenplum work. However I didn’t have time to get MADLib extensions working in Postgres (these come as part of out-of-the-box Greenplum). This is unfortunate as clearly one of the things that EMC/Pivotal/Greenplum would like is for more people to use MADLib. By the way, if you didn’t know, MADLib is a way of running advanced analytics in-database with the possibility of using Massively Parallel Processing to speed delivery of results.

The first couple of modules are of a high-level nature aimed more at Project Manager or Business Analyst type people. The presenter, David Dietrich, is clearly very comfortable with this material and appears to have had considerable experience at the business end of analytics projects. The material centres around a 6-step, iterative analytics methodology which seemed very sensible to me and would be a good framework for many analytics projects. It emphasises that much of the work will go into the early Discovery phases (i.e. the ‘What the hell are we actually doing?” phase) and particularly the Data Preparation (the unsexy bit of data projects). All in all this seemed both sensible and easy material.

Things start getting technical in Module 3 which provides background technicals on statistical theory and R, the open-source statistics software. The course assumes a certain level of statistical background and programming ability and if you don’t have that this is where you might start to struggle. As an experienced programmer I found R no problem at all and thoroughly enjoyed both the programming and the statistics.

The real meat of the course is Modules 4 and 5. Module 4 is a big beast as it dives into a number of machine learning algorithms: Kmeans clustering, Apriori decision rules, linear and logistic regression, Naive Bayes and Decision Trees. Throw in some introductory Text Analysis and you have a massive subject base to cover. This particular part of the course is exceptionally well-written and pretty well presented. I’m not saying it’s perfect but it is hard to over-state how difficult it is to cover all this material effectively in a relatively short-space of time. Each of these algorithms is presented with use-cases, some theoretical background and insight, pros and cons, and a lab.

It should be acknowledged that analytics and big data projects require a considerable range of skills and this course provides a broad-brush overview of some of the more common techniques. Clearly you wouldn’t expect participation on this course to make you an expert Data Scientist any more than you would employ someone to program in Java or C just based on courses and exams taken. I certainly wouldn’t let someone loose to administer a production Documentum system without being very sure they had the tough experience to back up the certificates. Somewhere in the introduction to this course they make clear that the aim is to enable the you to become an effective participant in a big data analytics project; not necessarily as a data scientist but as someone who needs to understand both the process and the technicals. As far as this is the aim I think it is well met in Module 4.

Module 5 is an introduction to big data processing, in particular Hadoop and MADLib. I just want to make 1 point here. This is very much an overview and it is clear that the stance taken by the course is that a Data Scientist would be very concerned with technical details about which analytics methods to use and evaluate (the subject of module 4), however the processing side is just something that they need to be aware of. I suspect in real-life that this dichotomy is nowhere near as clear-cut.

Finally Module 6 is back to the high-level stuff of modules 1 and 2. Some useful stuff about how to write reports for project sponsors and other non-Data Scientists and dos and don’ts of diagrams and visualisations. If this all seems a bit obvious it’s amazing how often this is done badly. As the presenter points out it’s no good spending tons of time and effort producing great analytics if you aren’t able to effectively convince your stakeholders of your results and recommendations. This is so true. The big takeaways: don’t use 3D charts, and pie charts are usually a waste of ink (or screen real estate).

If I have one major complaint about the content it is that Feature Selection is not covered in any depth. It’s certainly there in places in module 4 but given that coming up with the right features to model on can have a huge impact on the predictive power of your model there is a case for specific focus.

So overall I think this was a worthwhile course as long as you don’t have unrealistic expectations of what you will achieve. Furthermore if you want to get full value from the labs you are going to have to invest some effort in installing software (R and Greenplum/Postgres) and ‘munging’ data sets to use.

Oh, by the way, I passed the exam!

Documentum and Greenplum

January 14, 2013 at 8:30 am | Posted in Big Data | 1 Comment
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@Mikemasseydavis tweeted “will we see #documentum and #greenplum become a ‘platform'”. This aphorism obviously had some attraction since myself and 2 others retweeted it. In a way this is not a completely new idea as Generalli Hellas backed the notion of ‘xCP as the action engine for Big Data‘ which was one of the big ideas that came out of Momentum 2011. In fact EMC seem to have big ideas in this area as evidenced here.

I would ask the following questions:

  • How much effort are EMC going to put into this area? How fast will they be able to deliver?
  • Does a Greenplum connector for xCP and a feed into Greenplum constitute a platform? What else is needed to make it a platform?
  • What are the use cases? Gautam Desai mentions a document with 20 use cases.

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