Thursday, June 26, 2008


Yes, i have GTA 4. I have been playing on xbox for some time. Halo 3 was good. Awesome visuals - though my TV is not a HDTV and is just 20 inches - around 6 years old cheap one. But still the thrill of playing Halo 3, watching the visuals was good.

Mass Effect was still better. The amount of information associated with each character. How each character reacts to which situation. The power to choose between two different decisions. It was good in its own way.

And now it is GTA 4. I had played the original gta which was a 2d game on my home pc. But that time i was in college and the game was a simple demo. So, though i enjoyed it a lot, but still i wanted more. But, at that time purchasing a game was like a throwing money away. So, i simply enjoyed the 15 minute demo version of GTA.

And then on this sunday, i got the GTA-IV to run on my xbox. I was looking for Gears Of War. But it was not available. The shop keeper instead shoved a GTA-4 under my nose. And i was surprised to see a copy of the most wanted game available so easily. I jumped on it. Checked the seals to ensure that it was orignial and then got it for a hefty 2500/-. That is 2 months salary to my maid. Or 20-25 movies. Or a 80 GB HDD. And instead i spent so much on a single DVD of game.

Anyways, playing GTA is a good experience. In addition to stealing cars and beating up people for money, i could call and fix up meetings and dates with my friend and girl-friend. I could go to strip clubs and play pool. I could go on the internet inside GTA and search for information online. It is like a city where i could do whatever i want.

I have just completed 3-4 missions and am looking forward to more time to spend on it.

Few intersting links:

Missions :
Official Cheats :
Other cheats :

Wednesday, June 18, 2008

QA Tester Versus Developer

How Roshan D'Mello (QA Tester) frustrates developer (Mukesh Thakur)

Roshan D'Mello: Hey Mukesh, there is a bug in your code. Type a text in user name text box and press enter. Beep sound doesn't appear.

Mukesh Thakur: How can that be a bug? There is no requirement that beep sound should come. Anyway, I will assign it to offshore and get it fixed.

After 2 days,

Mukesh Thakur: Roshan, bug is fixed. Please verify.

After another 2 days,

Roshan D'Mello: I have re-opened the bug because sound is not coming in some PCs. Sound is coming in my machine, but my colleague Rajat Choudhry is not getting the sound.

After another 2 days,

Mukesh Thakur: Not a bug. I observed that your friend Rajat Choudhry has old IBM machine. Unlike your DELL machine, IBM machines do not have inbuilt speakers. So, to hear the sound in Rajat Choudhry's machine, please use head phones and then get the bug closed soon.

Another 2 days,

Roshan D'Mello: I have re-opened the bug because sound tone is different across different machines. Sound is coming as 'BEEP' in my machine, but my colleague Rajat Choudhry who is having IBM machine is getting the sound as 'TONG'.

Mukesh Thakur: Not a bug. Get lost man. What can we do for the bug? The two machines are built in such a way that they produce different sounds. Do you expect the developers to rebuild the IBM processors to make them uniform? Please close it.

Another 2 days,

Roshan D'Mello: I have re-opened the bug because intensity of beep sound produced on 2 different DELL machines is different. My machine produces beep sound of intensity 10 decibels whereas my friend's machine produces sound worth 20 decibels. Fix your code to make the sound uniform across all machines.

Another 2 days later,

Mukesh Thakur: Once again it is not a bug. I have noticed that the volume set is different on the two machines. Ensure that volume is same in both the machines before I get mad and then close the bug.

Another 2 days,

Roshan D'Mello: I have re-opened the bug.

Mukesh Thakur: What ?? Why? What more stupid reasons can be there for re-opening?

Roshan D'Mello: Sound intensity is different for machines placed at different locations (different buildings). So, I have re-opened it.

After 2 days,

Mukesh Thakur: I have made some scientists do an acoustical analysis of the two buildings you used for testing. They have observed that the acoustics in the two buildings varies to a large extent. That is why sound intensity is different across the 2 buildings. So, I beg you to please close the bugs.

After 1 year

Roshan D'Mello: I am re-opeing the bug. During the year, I requested the clients to arrange architects to build two buildings with same acoustical features, so that I can test it again. Now, when I tested, I found that intensity of sound still varying. So, I am re-opening the defect.

Mukesh Thakur: GROWLLLL.....I am really mad now. I am sure that the sound waves of the two buildings are getting distorted due to some background noise or something. Now I need to waste time to prove that it is because of background noise.

Roshan D'Mello: No need for that. We will put the machines and run them in vacuum and see.

Mukesh Thakur: (not alive)

Friday, June 13, 2008

vim configuration basic

Have you ever thought about configuring vim? The same vim that you use for editing your files (you should be very familiar with vi editor if you are using unix-like systems). Yes, the editor is highly configurable.

Here are some of the basic tips for vim - Vi Improved 7.1

The global configuration file resides at /etc/vim/vimrc. And the local configuration file resides at your home folder. So if you are logged in as jayant and your home folder is /home/jayant, then your local configuration file would be /home/jayant/.vimrc. If you do not see color in your vi editor, you can do the following

syntax on
set background = dark

I have set the following as my default configuration

jayant@jayantbox:~$ cat .vimrc
set autoindent
set cmdheight=2 "command bar is 2 high
set backspace=indent,eol,start "set backspace function
set hlsearch "highlight searched things
set incsearch "incremental search
set ignorecase "ignore case
set textwidth=0
set autoread "auto read when file is changed from outside
set ruler "show current position
" set nu "show line number
set showmatch "show maching braces
set shiftwidth=2
set tabstop=2
set gfn=Courier\ 12
set t_Co=256
colorscheme oceandeep

This sets the tab width to 2 chars instead of the default 8. Color Scheme is changed to oceandeep. You can get Color schemes for vim from Your color schemes have to be put in <home>/.vim/colors folder. Auto indenting has been turned on, so you dont need to press tab to indent your code.

Check out my vim using the oceandeep color scheme

Wednesday, June 04, 2008

MySQL versus PostgreSQL - part II

My earlier post mysql versus postgresql brought me lots of negative comments - that i did not compare the transactional database of pgsql with the transactional engine (innodb) of mysql. The main reason why i did not do that was because i had found InnoDB to be very slow as compared to MyISAM.

But after all those comments i ran the benchmarks again using the same scripts and the same technology on the same machine (my laptop) and here are the results. I created a new table in both Mysql (using InnoDB engine) and pgsql. And i disabled the binary logging in mysql to speed up insert/update/delete queries. Please refer to the earlier post for the setup information.

Following notification would be used :

<operation(select/insert/update/delete)> : <no_of_threads> X <operations_per_thread>

  • Firstly i ran single thread with inserts both before and after disabling binary logging in mysql
    Mysql Insert : 1 X 100000
    Time : 65.22 Sec (binary logging enabled)
    Time : 32.62 Sec (binary logging disabled)
    So disabling binary logging in mysql would make your insert/update/delete queries take half the time.
    Pgsql Insert : 1 X 100000
    Time : 53.07 Sec
    Inserts in mysql are very fast.

  • Selects : 2 X 100000
    Mysql time : 30.1 Sec
    Pgsql time : 29.92 Sec
    Both are same

  • Updates : 2 X 50000
    Mysql time : 29.38 Sec
    Pgsql time : 36.98 Sec
    Mysql updates are faster

  • Ran 4 threads with different no_of_operations/thread
    Run 1 [Select : 1 X 100000, Insert : 1 X 50000, Update : 1 X 50000, Delete : 1 X 20000]
    Mysql time : 40.86 Sec
    Pgsql time : 45.03 Sec
    Run 2 [Select : 1 X 100000, Insert : 1 X 100000, Update : 1 X 50000, Delete : 1 X 10000]
    Mysql time : 49.91 Sec
    Pgsql time : 63.38 Sec
    Run 3 [Select : 1 X 100000, Insert : 1 X 20000, Update : 1 X 20000, Delete : 1 X 1000]
    Mysql time : 29.83 Sec
    Pgsql time : 29.3 Sec
    It could be seen that increasing the amount of insert/update/delete queries affects the performance of pgsql. Pgsql would perform better if number of selects are very high. Whereas mysql-innodb performs better in all cases

  • Had 4 runs with different no of threads.
    Run 1: 12 threads [Select : 2X30000 + 3X20000, Insert : 1X20000 + 2X10000, Update : 2X10000, Delete : 2X1000]
    Mysql time : 31.16 Sec
    Pgsql time : 30.46 Sec
    Run 2: 12 threads [Select : 2X50000 + 2X40000 + 1X30000, Insert : 1X20000 + 2X15000, Update : 2X15000, Delete : 2X2000]
    Mysql time : 52.25 Sec
    Pgsql time : 53.03 Sec
    Run 3: 20 Threads [Select : 4X50000 + 4X40000 + 2X30000, Insert : 2X20000 + 3X15000, Update : 2X20000 + 1X15000, Delete : 2X5000]
    Mysql time : 169.81 Sec
    Pgsql time : 136.04 Sec
    Run 4: 30 Threads [Select : 2X50000 + 3X40000 + 3X30000 + 3X20000 + 4X10000, Insert : 1X30000 + 2X20000 + 3X10000, Update : 3X20000 + 3X10000, Delete : 1X10000 + 2X5000]
    Mysql time : 200.25 Sec
    Pgsql time : 156.9 Sec
    So, it can be said that for a small system with less concurrency, mysql would perform better. But as concurrency increases, pgsql would perform better. I also saw that while running the pgsql benchmark, the system load was twice than while running mysql benchmark.

Enabling mysql binary logging for replication would ofcourse add an over head. Similarly enabling trigger based replication in pgsql would be another overhead. The fact that replication in mysql is very closely linked with the database server helps in making a high availability system easier. Whereas creating slaves using replication in pgsql is not that easy. All available products for replication in pgsql are external - 3rd party softwares. Still, for a high concurrency system pgsql would be a better choice.

Tuesday, June 03, 2008

MySQL versus PostgreSQL

I created and ran some simple tests on mysql and postgresql to figure out which one is faster. It is already known that postgresql is more stable and reliable than mysql. pgsql has a rich set of features. It is a complete RDBMS and also supports fulltext search.

All benchmarks were done on my laptop - Intel core 2 duo (2.0 GHz) with 4MB L2 cache & 2 GB ram. I have 64 Bit ubuntu system loaded with MySQL 5.1.24-rc (64 bit binary) and PostgreSQL 8.3.1 (compiled from source).

I used python as a scripting language for writing down my benchmark scripts. I used psycopg2 as a connector from python to postgres and mysql-python as a connector from python to mysql.

The benchmarking was done in phases. Firstly simple Insert, update and select queries were run to check the raw speed of these queries. Then threads were created to run simultaneous insert, update, select and delete queries. I checked the benchmark times for different number of concurrent threads.

I created a simple table on both mysql and pgsql. I used the MyISAM database engine to create table in mysql. :

ABC(id int not null auto_increment primary key, value varchar(250));

Queries that were run are:

Insert(I) : Insert ignore into ABC (id, value) ...(For pgsql, a rule has to be created to ignore duplicate inserts)
Update(U) : Update ABC set value=<something> where id=<random_id>
Select(S) : Select * from ABC where id=<random_id>
Delete(D) : Delete from ABC where id=<random_id>

  • Insert - 100000 rows in 1 thread
    Time taken for Mysql : 20.8 seconds
    Time taken for Pgsql : 58.1 seconds
    So, raw insert speed of mysql is much better as compared to pgsql

  • 100000 selects in 1 thread
    Time taken for Mysql : 21.76 seconds
    Time taken for Pgsql : 20.15 seconds
    Raw selects are better in pgsql as compared to mysql

  • Selects - 2 threads of 100000 selects
    Time taken for Mysql : 40.46 seconds
    Time taken for Pgsql : 27.38 seconds
    So, if i increase the concurrency of selects, pgsql perfors much than mysql

  • Update - 2 threads of 50000
    Time taken for Mysql : 23.97 seconds
    Time taken for Pgsql : 34.03 seconds
    Mysql looks better in handling updates here.

  • 4 Threads
    Run 1 : [100000 Selects, 50000 Inserts, 50000 Updates, 20000 Deletes]
    Time taken for Mysql : 45.25 seconds
    Time taken for Pgsql : 54.58 seconds
    Run 2 : [100000 Selects, 100000 Inserts, 50000 Updates, 10000 Deletes]
    Time taken for Mysql : 59.05 seconds
    Time taken for Pgsql : 69.38 seconds
    Run 3 : [100000 Selects, 20000 Inserts, 20000 Updates, 1000 Deletes]
    Time taken for Mysql : 35.54 seconds
    Time taken for Pgsql : 31.23 seconds
    These runs show that Mysql is good when you have very large no of inserts/updates/deletes as compared to selects. But pgsql's performance surpasses that of mysql when the number of selects are much higher.

  • Finally, lets approach the real life scenario where generally the number of selects are much more than the number of inserts and there are multiple threads performing selects and inserts.
    I will use the following notification here - <no_of_threads> X <no_of_operations(select/insert/update/delete)_per_thread>
    So, for example 3 X 20 Selects = 3 threads of 20 Selects in each thread

    Run 1 : [2 X 30000 selects, 3 X 20000 selects, 1 X 20000 inserts, 2 X 10000 inserts, 2 X 100000 updates, 2 X 1000 deletes] Total - 12 threads
    Time taken for Mysql : 42.28 seconds
    Time taken for Pgsql : 44.28 seconds
    Both Mysql and Pgsql are almost at par.

    Run 2 : [2 X 50000 selects, 2 X 40000 selects, 1 X 30000 selects, 1 X 20000 inserts, 2 X 15000 inserts, 2 X 15000 updates, 2 X 2000 deletes] Total - 12 threads but number of selects are quite high
    Time taken for Mysql : 61.02 seconds
    Time taken for Pgsql : 48.60 seconds
    So, as we increase the number of operations (specially selects) mysql's performance degrades, whereas pgsql's performance remains almost the same

    Run 3 : [4 X 50000 selects, 4 X 40000 selects, 2 X 30000 selects, 2 X 20000 inserts, 3 X 15000 inserts, 3 X 15000 updates, 2 X 3000 deletes] Total - 20 threads (10 threads for select, 5 for insert, 3 for update and 2 for delete) Which is the normal trend in database servers.
    Time taken for Mysql : 169.31 seconds
    Time taken for Pgsql : 128.7 seconds
    Bingo, so as concurrency increases pgsql becomes faster than mysql.

My earlier benchmarks with pgsql 7.x was not as good as this one. With postgresql 8.3.1, the speed of serving concurrent requests has increased a lot. So, in a high concurrency environment, i would generally recommend to go ahead with using postgresql rather than mysql.

Please check the comments section. We have some really interesting comments there...