Tuesday, November 23, 2010

Codemotion 2011, the most important Italian conference about programming



Save this date: March 5th 2011! In Rome, Italy there will be the most important conference about programming. The event is totally FREE. About 1,500 attendees. Sessions in English and Italian languages.

For information: http://www.codemotion.it


Tuesday, October 19, 2010

When someone is criticizing something you care...

When someone is criticizing something you care, don't defend it till death, but ask him what's his idea to improve it! Both will growth. Lvc@

Thursday, October 14, 2010

A standard for GraphDB

Yesterday GraphDBs have covered a niche market. In the last period things are changed and they are becoming much more popular than ever. This is due to:
  • The always growing need to have data strongly interconnected. What better than a GraphDB for it?
  • Applications are much more "social" than before. And social means relationships among subjects that perfectly bound to the Graph model
  • Performance on large datasets. You can live without a pure GraphDB, and therefore continue to use a Relational DBMS, until you need a real fast access to your data
  • The NoSQL movement has contributed a lot to change the mind of developers to focus to DBMS different (and sometime very different) from the Relational model.

The GraphDB has few but strong concepts. Graphs are composed by:
  • Vertex or Node, the linked entity. Vertexes can have properties.
  • Edge or Arc, as the link between the Vertexes. Edges can have properties and can be unidirectional or bidirectional
  • Property, is a value to assign to Vertexes and Edges. A property has a name and a value
Each GraphDB product is based upon the above concepts, but features can be very different among them. Furthermore there isn't a standard for them and an application can't migrate from one to another one at zero or low cost.

This is the reason why I want to introduce the Tinkerpop Blueprints. This Open Source project aims to have a shared set of basic interfaces to abstract the concepts of Graph, Vertex, Edge and Property. In this way applications can easily migrate to another available implementation of the specification.

Furthermore Tinkerpop has created a complete stack of tools and framework to work with Graphs. Below the main ones:
  • Gremlin is a Turing-complete, graph-based programming language designed for key/value-pair multi-relational graphs. Gremlin makes use of an XPath-like syntax to support complex graph traversals. This language has application in the areas of graph query, analysis, and manipulation.
  • Rexster is a RESTful graph shell that exposes any Blueprints graph as a standalone server. Extensions support standard traversal goals such as search, score, rank, and, in concert, recommendation. Rexster makes extensive use of Blueprints, Pipes, and Gremlin. In this way its possible to run Rexster over various graph systems.
  • Pipes is a graph-based data flow framework for Java 1.6+. A process graph is composed of a set of process vertices connected to one another by a set of communication edges. Pipes supports the splitting, merging, and transformation of data from input to output.

(1) What do you think about this effort to standardize GraphDB?

(2) What is missed today in Tinkerpop Blueprints API?

(3) Does a .NET porting make sense?

Tuesday, September 28, 2010

Working on large datasets in OrientDB

I was really busy in the last 5 days because I'was working in a huge rewriting of the RB+Tree algorithm that is behind the OrientDB index system. All is started some days ago when in the OrientDB Group the user Mark Harwood was sharing the first experiences in the import of the entire Internet Movie Data Base (IMDB) inside an OrientDB instance. We're talking about 13 millions of Vertices and about 8 millions of Edges.

Well, performance seemed good, specially in comparison with Neo4J, but the insertion time was not-linear and after some millions of records the engine slow down a lot. Furthermore a nasty bug in the management of multiple segments broke the import job after some minutes in his machine while on my PC all went correctly.

This is the reason why I stopped the development of the Cluster feature in favor of a strong review of the RB+Tree algorithm. Indexing has been alway fast, but the Mark Harwood's case stressed the engine as no one did until now. The reason is in the import process itself that executes random reads into the index while the RB+Tree seemed optimized for sequential insertion and retrieval.

I'm fixing all the pending issues but first benchmarks show a speed improvement in Indexing between 100% and 800%! Furthermore times now are really linear. Inserting the first millions of Vertices is the same of the last million. This is a big result to the already super-fast OrientDB engine.

Once finished the test phase (with new Unit tests, of course) I'll commit all the changes in SVN to be reviewed by the community before the next release.

Thursday, September 16, 2010

Started the development of OrientDB clustering

Today is a new day, the day after the official release of OrientDB version 0.9.22. I apologize to all the requesters of the issues planned for this release and not yet finished and postponed to the 0.9.24. What is the reason?

---> Replication, Clustering, Fault-Tolerance <---

Seems that the most missed feature in OrientDB is the support for clustering, and therefore high scalability, high availability and high volume of transactions that a single node can't handle. In the last months I studied the whole different architectures of other NoSQL solutions for clustering.

Today is a new day because I'll start the development of clustering for OrientDB with the following features:
  • Master-Slaves type, where it can be only one Master and N Slaves. If the Master crashes a Slave is elected to be the new Master
  • IP multicast to discover cluster nodes
  • Configuration of nodes using TCP/IP, useful for Clouds that don't allow the IP multicast
  • Two sync modes: full where all the database is compressed and sent over the network, and partial by sending only the changes happened since the last sync
  • New database handled by the Master OrientDB Server instance to store all the pending records until a configurable threshold. Up this threshold the logs are deleted and the node need a full-sync on startup
  • New console commands to display nodes, listen clustering messages and elect the master manually
The release 0.9.23 is planned for the October 15th, 2010. Stay tuned and contribute with comments, ideas or critiques.

Wednesday, September 15, 2010

Released OrientDB 0.9.22

Hi all,
many thanks to all the contributors for this new piece of software. A new version of OrientDB has been released after more than 1 month of work (and holidays).

Starting from this version you can use OrientDB as a pure GraphDB using the custom API (http://code.google.com/p/orient/wiki/GraphDatabase), by the Tinkerpop stack (Blueprints, Gremlin, Pipes, etc.) or again by using the Erlang language with the Cali project (http://github.com/dmitriid/cali).

Direct URL to download: http://orient.googlecode.com/files/orient-database-0.9.22.zip

New features:
- Issue 21: Full text index against schema fields
- Issue 91: SQL UPDATE against collections and maps
- Issue 94: Support for GREMLIN graph language
- Issue 108: Regular expression support in WHERE clause
- Issue 109: Support for memory clusters inside regular persistent database

Bugs:
- Issue 86: Cannot insert record from console
- Issue 87: Cannot query records from OrientDB Studio Command-page
- Issue 100: Transaction does not work as expected
- Issue 101: Error in using orient queries having ' character
- Issue 104: Bulk record creation in cluster with pre-created indices causes ClassCastException
- Issue 105: Error in using UPDATE query
- Fixed other minor bugs

The next release is planned for the end of September 2010 with the first version of Clustering support. Here the details: http://code.google.com/p/orient/issues/list?q=label:v0.9.23

To test the OrientDB Studio go here: http://www.moobilis.com:2480. Users: reader/reader and writer/writer. To manage the server: root/root.

If you'd like to suggest some new feature for the next releases please open a New Issue as "New feature": http://code.google.com/p/orient/issues/entry?template=New%20feature

Saturday, September 11, 2010

Erlang interface for OrientDB and micro-benchmark between NoSQL DBMSs

Dmitrii 'Mamut' Dimandt made a micro benchmark against Neo4J, Redis, ThinkerGraph (in memory only) and OrientDB using the erlang language. These are the results:http://github.com/dmitriid/cali/wiki/Benchmarks-of-sorts.

OrientDB is the fastest implementation (only ThinkerGraph is faster but it's not a DBMS since works only in memory). It's nice to see that OrientDB performance are very close to the in-memory only implementation.


Thursday, September 09, 2010

OrientDB the fastest GraphDB available today?

Two days ago I've finished the integration of the last part of the Blueprints: the Index. Now OrientDB can be used as for Neo4J with the entire ThinkerPop stack. This include the Gremlin language as well.

First tests shows that OrientDB outperforms Neo4J, the market leader of GraphDB, in all the tests but the iteration (and therefore counting). This is due to the implementation of the Blueprints that need to create a new wrapper object to contain the OrientDB's OGraphVertex and OGraphEdge objects. I've some ideas to improve it, but I need more time for it. Maybe in the next weeks or earlier if some users need it. However using native OrientDB Graph APIs this overhead is removed.

These are the results:

Test name Description Time in ms (less is better) OrientDB vs Neo4J
OrientDB 0.9.22 Neo4J + faster, - slower
testVertexEquality 1 vertex added and retrieved in 4.74 2.33 -203,4%
testRemoveVertexNullId 1000 vertices added in 216.73 2,070.74 +955,4%

1000 vertices deleted in 1,093.71 1,910.02 +174,6%
testVertexIterator 5000 vertices added in 476.62 8,314.04 +1.744,4%

5000 vertices counted in 86.94 1.60 -5.433,8% *
testAddManyVertexProperties 750 vertex properties added (with vertices being added too) in 72.34 43,437.29 +60.046,0%
testAddEdges 6 elements added and checked in 0.79 30.70 +3.886,1%
testAddManyEdges 3000 elements added in 2,314.44 8,031.12 +347,0%

1000 edges counted in 8.45 12.54 +148,4%

2000 vertices counted in 31.62 0.51 -6.200,0% *

2000 vertices checked in 98.27 14.05 -699,4% *
testGetEdges 3 edges retrieved in 0.45 0.12 -375,0%
testRemoveManyEdges 200 vertices counted in 167.28 0.14 -119.485,7% *

100 edges counted in 34.92 0.79 -4.420,3% *

100 edges removed and graph checked in 20,555.44 332.54 -6.181,3% *
testStringRepresentation 1 graph string representation generated in 0.01 0.01 100,0%
testClear 75 elements added in 45.89 152.87 +333,1%

75 elements deleted in 30.76 422.05 +1.372,1%
testRemovingEdges 500 vertices added in 133.62 974.37 +729,2%

1000 edges added in 1,130.64 4,521.90 +399,9%

1000 edges deleted (with size check on each delete) in 36,773.66 4,411.69 -833,6% *
testRemovingVertices 500 vertices added in 10.48 1,110.03 +10.591,9%

250 edges added in 132.32 1,089.45 +823,3%

500 vertices deleted (with size check on each delete) in 70,675.74 2,140.07 -3.302,5% *
testTreeConnectivity 1464 vertices added in a tree structure in 1,506.82 5,832.02 +387,0%

1464 vertices iterated in 427.67 0.75 -57.022,7% *

1463 edges iterated in 9.89 5.39 -183,5% *
testTinkerGraphEdges graph-example-1 loaded in 43.75 541.15 +1.236,9%
testTinkerGraphVertices graph-example-1 loaded in 6.81 520.29 +7.640,1%
testTinkerGraphSoftwareVertices graph-example-1 loaded in 5.31 543.02 +10.226,4%
testTinkerGraphVertexAndEdges graph-example-1 loaded in 5.01 544.17 +10.861,7%

* are the tests with iteration

Thursday, August 12, 2010

Yesterday Mike Tallent, via Twitter, made his congratulations to me for my recent "Db4o community award".

Is it a joke? The reason seems to reside in the homepage of TevereFlow that claims to support db4o. After some private messages with a db4o guy I explained that TevereFlow supports db4o since it uses DataNucleus as OR-Mapping and it supports db4o. Therefore TevereFlow can run on top of db4o but the support is indirect. All clear.

But after some days I found my name in the "DB4O MOST VALUES PROFESSIONAL" list:



Thanks a lot, but I never have written a single line of code for/with db4o!

Furthermore I'm the author of OrientDB, a competitor of db4o.

So is it a joke? :-)

Friday, February 19, 2010

Romulus workshop in Madrid

Madrid, February 18th 2010. The day seems to be finished and it has been a pretty long day for me. This morning wake up at 7:30 o'clock, 8:30 breakfast at the Starbucks in front at the hotel and then straightforward to the Universidad Polit├ęcnica de Madrid (UPM) for the Romulus meeting and for the Romulus Workshop in the afternoon.

Today I've presented Roma Meta Framework to a bunch of students and some business IT men interested on the fast developing of Web Applications following the DDD approach, the Meta Framework philosophy and obviously Roma. We have had a hands-on session where almost all the attendees tried to follow me step by step on the building of a simple social application. I hope today the Roma community welcomes some new committers.

Below some photos shooted by Marco.



Anyone is in Madrid until Saturday morning?

Saturday, February 13, 2010

Orient DB almost ready for the show time!

After some weekends of work I've in my hands the first version of Orient DB! I wrote a lot of Unit Tests that helped me a lot on the heavy refactoring in order to achieve the best performance than ever. The main features of Orient are:
  • Full ACID: Optimistic transaction available with recovery of aborted transactions when the engine restarts. Tested with 1 billion of records even with simulated crashes during the commit phase. Pessimistic (with object-level locking) transaction in the next releases.
  • Extremely light: less than 400kb of jar without any dependency with other libraries
  • Super fast: stores 1,000,000 (yes one million) of records in 3.5 seconds on common hardware (my notebook). The KeyValue engine stores 100,000 entries indexed in 9 seconds. Lookups are so fast as memory access.
  • tested up to 1 billion of records, but the limits are up to 9.223.372.036 Billions. Actually I think I'll never will be able to include this test in my Unit tests :-)
  • A lot of cool features such as Asynchronous Queries, SQL language, Partitioning of data, native sharding support, and more
  • Requires: Java5 or major and run on all the most used Operative Systems.
What about the license? I have no choose yet, maybe LGPL?

http://www.orientechnologies.com.