Interesting Database Management Systems

Recently I was looking for highly scalable database management systems (other than RDBMS) and the following ones caught my attention. 

Object database management systems:
ODBMS products like Cache claim that it can run SQL 5 times faster than relational databases. They also enable extraordinary transaction processing speed, massive scalability, and real-time queries against transactional data with minimal maintenance and hardware requirements.Have a look at Cache ODBMS @http://www.intersystems.com/cache/index.html
There are also other good ODBMS products like Gemstone, Cerebrum, db4o of which db4o is an open source, fully functional ODBMS with nice documentation. Have a look at it @ http://www.db4o.com

NoSQL database management systems:
 These databases are referred as structured database management systems, which scale horizontally and don’t need fixed table schemas. They can service heavy read/write workloads when compared to traditional RDBMS.   Some of the popular NoSQL database management systems include Google’s BigTable, Amazon’s Dynamo, and Apache Cassandra.
http://labs.google.com/papers/bigtable.html
http://www.allthingsdistributed.com/2007/10/amazons_dynamo.html
http://cassandra.apache.org/

Interesting Myths about C# : 1) Not everything in C# derives from Object 2) Does value types always allocated on the stack ??

Here are the links for some of the nice articles written by Eric Lippert.. The design engineer at Microsoft's developer Division

Not Everything in C# derives from System.Object

http://blogs.msdn.com/b/ericlippert/archive/2009/08/06/not-everything-derives-from-object.aspx

Does Value types always allocated on the stack ?

http://blogs.msdn.com/b/ericlippert/archive/2009/04/27/the-stack-is-an-implementation-detail.aspx

Another Important article by Alexandra Rusina which explains the difference between dynamic and object keywords usage

http://blogs.msdn.com/b/csharpfaq/archive/2010/01/25/what-is-the-difference-between-dynamic-and-object-keywords.aspx

Interesting Questions - Expert Answers Part 3

This is the question i posed to Jeffery Ritcher on 6th March 2010

Question ( Gopala ) :
As per your words i got to know that, when  CLR intializes the threadpool gets initialized with  zero threads ..Also, the the threads are created and used but they are not destroyed instead retained in the threadpool for later use.
But in some articles( For ex : In " C# Threading handbook" by Tobil Titus) i have found out that CLR Intializes the theadpool with 25 ( defalut, and we can change this value) threads
To Verify this i tried the following code on VS2010 ( .NET 4.0)

int workerThreads1, completionPortThreads1; int workerThreads2, completionPortThreads2; int workerThreads3, completionPortThreads3;

ThreadPool.GetAvailableThreads(out workerThreads1, out completionPortThreads1);
 //workerThreads1 = 1023 completionPortThreads1 = 1000

ThreadPool.GetMaxThreads(out workerThreads2, out completionPortThreads2);
// workerThreads2 = 1023 completionPortThreads2 = 1000

ThreadPool.GetMinThreads(out workerThreads3, out completionPortThreads3);
//workerThreads3 = 2 completionPortThreads3 = 2

The results seems to be contradictary.Please Advise.

Answer ( Jeffery Ritcher) :
 
Initially the thread pool has 0 threads in it.
However, the number of worker threads in the pool can grow to 25 per CPU (by default). 25 was the number for earlier versions of the CLR.
In .NET 4.0 the default is 1023 worker threads (instead of 25) and 1000 I/O threads.
The CLR doesn’t like to create threads but, if there are work items queued up, it will quickly create up to min threads (2) and then it will slowly create more threads up to the max threads (1023).
GetAvailableThreads returns the number of threads that the thread pool could use for doing work if work gets queued up. This number changes all the time. This number does not include thread pool threads are currently doing work but these threads could return and more thread pool threads could initate doing work and this is why the number changes all the time.

Microsoft patent on " The idea of zero"

This  is an interesting patent filed by Microsoft :
 "“an operator that returns true when two memory addresses are not equal”!
Have a look at it @

http://appft1.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PG01&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.html&r=1&f=G&l=50&s1=%2220040230959%22.PGNR.&OS=DN/20040230959&RS=DN/20040230959

Also, have a look at the "INTELLIGENT CONTAINER INDEX AND SEARCH" patent filed by microsoft 3 days back @

http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=120&f=G&l=50&d=PG01&s1=microsoft&p=3&OS=microsoft+search&RS=microsoft

Moving E-mails from one account to another

Often we need to move e-mails from one mail account to another. Here is the way.

1) Source : YahooMail, AOL, Gmail       Destination : HotMail

    Use TrueSwitch

2) Source : HotMail, AOL, Gmail    Destination : YahooMail

    Use TrueSwitch

3) Source : HotMail, AOL       Destination : Gmail

    Use Google’s built-in MailFetcher

4) Source : YahooMail     Destination : Gmail

     First Transfer all your yahoo mails to hotmail using TrueSwitch

    Then transfer mails from HotMail to Gmail using Google’s built-in MailFetcher

Also you can use products like Yippie Move for moving emails from account to another  but it is a paid service.

Cheers!