Hadoop 0.21 update

2011-04-30T17:01:00.000+05:30

This is an update for setting up hadoop. There have been some changes in configuration files and startup/shutdown scripts Following configuration files are to be created in /conf folder hdfs-site.xml hadoop.tmp.dir /home/hadoop/hadoop-${user.name} A base for other temporary directories.

An encounter with Dominos

2011-03-07T23:28:00.000+05:30

I have been ordering dominos pizza since ages - my favourite - mexican green wave - cheese burst. This is the first time that Dominos created an environment where i needed to write a blog to express. At 8:37 today (7-3-2011) i placed an order for mexican green wave - cheese burst. Order no 140 at the Dominos outlet at sector 12, vasundra, Ghaziabad. The pizza was delivered in exactly 30 minutes

how to go about apache-solr

2010-12-12T18:26:00.001+05:30

I had explored lucene for providing full text search engines. I had even gone into the depth of modifying the core classes of lucene to change and also add new functionality into lucene. Being good at lucene, i never looked at solr. I had the notion that Solr was a simple web interface on top of lucene so it will not be very customizable. But recently my belief was broken. I have been going

Carnation - is it really worth getting your car serviced there ??

2010-12-12T14:30:00.000+05:30

Before I go ahead with a walk through of my experience, I would like you to answer some questions 1. Was the cost of your service at carnation higher than the cost of your normal service at your earlier service center? 2. Were some parts found to be faulty? Are you sure they were faulty? 3. Did you ever get a call asking for a feedback? 4. If you were offered tea/coffee and you said yes - did you

Samsung and me

2010-12-12T12:45:00.002+05:30

I and samsung do not have a very long relation, but whatever relation we have is very flawed. I have been trying to "believe" in samsung products, in their "limitless" support. But samsung makes it difficult for me to "believe" in them. Lets take case by case what has happened in the past 4 years. I got a samsung refrigerator and a washing machine around 3 years back. The life of the

Foursquare outage post mortem

2010-10-08T10:59:00.000+05:30

As many of you are aware, Foursquare had a significant outage this week. The outage was caused by capacity problems on one of the machines hosting the MongoDB database used for check-ins. This is an account of what happened, why it happened, how it can be prevented, and how 10gen is working to improve MongoDB in light of this outage. It’s important to note that throughout this week, 10gen and

Database speed tests (mysql and postgresql) - part 3 - code

2010-10-01T12:52:00.001+05:30

Here is the code structure dbfuncs.php : is the file which contains classes and functions for firing queries on mysql and pgsql mysqlinsert.php : creates and fires inserts on mysql mysqlselect.php : creates and fires selects on mysql pgsqlinsert.php : creates and fires inserts on pgsql pgsqlselect.php : creates and fires selects on pgsql benchmark.php : script used to control concurrency and

Database speed tests (mysql and postgresql) - part 2

2010-09-29T17:33:00.000+05:30

Here is the comparison between mysql and postgresql for selects (only). I had used the same table that i had created earlier http://jayant7k.blogspot.com/2010/09/database-speed-tests-mysql-and.html while comparing insertion speed. I have created approximately 1,000,000 records in the table and ran selects on them. I also modified the configuration of both mysql and postgresql to enable faster

Database speed tests (mysql and postgresql) - part 1

2010-09-27T16:48:00.003+05:30

There has been major changes in mysql and postgres over a couple of years. Mysql has been focusing on improving and optimizing innodb. Postgres on the other hand has been focusing on database replication and hot standby. Recently postgres came out with version 9.0 which has built-in replication and hot standby - the two most requested feature in postgresql. Earlier people used to shy away from

Strategies to address scalability

2010-09-14T18:10:00.000+05:30

There are some very fundamental scalability strategies which i will try to list here. These may have detailed and varied implementations. Horizontal scalability - distribute the load : A very basic strategy for scalability is the ability to distribute the load or the requests across multiple processing units. Your code should be modular

Converting myisam tables to innodb

2010-09-10T14:33:00.000+05:30

Why should you convert myisam tables to innodb ? For the perfectly simple reason that innodb tables do not get locked by concurrent selects & inserts. So if you find that your myisam table is suffering for too many locks - due to concurrent selects and inserts, it is time for you to covert the table to innodb. The simple query which does the trick is Alter table myisam_table_name engine =

Hashing algos : Consistent Hashing

2010-09-07T12:14:00.000+05:30

Hashing is a way of mapping keys to locations. Normally you would hash by using a simple Key%n algorithm - which ensures that keys are mapped evenly across n splits. The problem with this algo is that adding or removing a node (or a split) would require a complete rehash of all the keys. And if you have a huge data set, it is ideally not feasable to rehash and re-distribute the keys.

Troubleshooting : mysql server has gone away

2010-08-23T10:48:00.000+05:30

When running query against a database the following error can be generated: ERROR 2006 (HY000) at line NNN: MySQL server has gone away Where "NNN" is the line number of the script currently being run where the error occurred. Possible Causes and Resolution This is a general error which can have a number of possible causes. The one certainty is that the MySQL database is no longer listening on

Linked-in data infrastructure

2010-08-05T10:26:00.000+05:30

Jay Kreps of LinkedIn presented some informative details of how they process data at the recent Hadoop Summit. Kreps described how LinkedIn crunches 120 billion relationships per day and blends large scale data computation with high volume, low latency site serving. Much of LinkedIn's important data is offline - it moves fairly slowly. So they use daily batch processing with Hadoop as an

Cassandra Data model : WTF is a supercolumn

2010-07-29T10:59:00.002+05:30

BTW: this is long. If you’d rather have a PDF version of this you can download it here. The Pieces Let’s first go thru the building blocks before we see how they can all be stuck together: Column The column is the lowest/smallest increment of data. It’s a tuple (triplet) that contains a name, a value and a timestamp. Here’s a column represented in JSON-ish notation: { // this is a column

mysql hack - altering huge tables

2010-06-29T12:31:00.000+05:30

You have a huge mysql table - maybe 100 GB. And you need to run alter on it - to either add an index, drop an index, add a column or drop a column. If you run the simple mysql "alter table" command, you will end up spending ages to bring the table back into production. Here is a simple hack to get the thing done. The benefit of the hack is that the alter runs quite fast. But since this is a hack

How Solar Power Works

2010-06-22T12:18:00.000+05:30

What is solar energy ? Solar energy is radiant energy which is produced by the sun. Each day the sun radiates, or sends out, an immense amount of energy. The sun radiates more energy in a second than people have used since the beginning of time! The energy of the Sun originates from within the sun itself. Like other stars, the sun is mostly a big ball of gases––mostly hydrogen and helium atoms.

Writing your first map-reduce program on hadoop

2010-06-16T17:57:00.000+05:30

Before we go ahead with the actual program, lets have a look at what map-reduce is and its usage. Map-Reduce is a programming model or concept which helps in implementing and processing large scale data sets. MapReduce model consists of two functions map() and reduce(). The map() function is applied to all input items in the input data set converting them to a set of key-value pairs. Multiple

Innodb now supports native AIO on Linux

2010-06-07T16:52:00.000+05:30

With the exception of Windows InnoDB has used ’simulated AIO’ on all other platforms to perform certain IO operations. The IO requests that have been performed in a ’simulated AIO’ way are the write requests and the readahead requests for the datafile pages. Let us first look at what does ’simulated AIO’ mean in this context. We call it ’simulated AIO’ because it appears asynchronous from the

Postgresql tuning - quick tips

2010-06-04T17:03:00.000+05:30

The configuration file for postgresql is located in /data/postgresql.conf You can alter the following settings in the config for better performance of postgresql. # listen to all ip addresses listen_addresses = '*' # should not exceed 1000. Req 400 bytes per connection max_connections = 500 # used for managing connection, active operations # should be 1/4 of the

Quick sort algorithm

2010-05-28T10:26:00.000+05:30

Quicksort follows the simple strategy of dividing the data into parts and sorting it. Simple steps for the algorithm are: Pick an element, called a pivot, from the list. Reorder the list so that all elements with values less than the pivot come before the pivot, while all elements with values greater than the pivot come after it (equal values can go either way). After this partitioning, the

Setting up replication on postgresql9.0 beta

2010-05-19T12:12:00.000+05:30

Eventually postgresql comes out with its inbuilt replication solution in 9.0 beta. Setting up of replication is quite simple. We will look at setting up a simple master-slave replication between two servers of postgresql. The way replication works in postgres is that the master keeps on writing "write ahead log" files (also known as wal files). The slave can be configured to run either in

An intro to Thrift

2010-04-09T12:00:00.001+05:30

What is thrift - a software framework for scalable cross language service development. It combines software stack with a code generation engine to build services that work efficiently and seamlessly between C++, Java, Python, Ruby, Erlang, Perl, Smalltalk etc. Thrift allows you to define data types and service interfaces in a simple definition file. Taking the definition file as input the thrift

Design patterns : Decorator pattern

2010-03-22T17:24:00.000+05:30

A decorator is a class which wraps the original class. This allows the user to extend the functionality of certain objects at runtime. The pattern is designed in a way that multiple decorators can be stacked on top of each other. Decorators are used to avoid the rigidity that subclassing provides. php example

Storing trees in databases

2010-03-05T14:48:00.000+05:30

A tree is a graph which is connected, uni-directed and acyclic. Lets look at different options of storing such trees in databases. Parent - Child Model The most common model for storing hierarchical information is storing the reference of the parent node along with the child node. so for a tree EmployeeBosssalary ANULL1000 BA900 CA950 DC800 EC700 FC600 For this model, the table to be

Options available for heating water

2010-02-28T19:09:00.001+05:30

The simplest and easiest way is to get a big utensil and fill it up with water and heat it on the stove. Remember to cover it up, and it gets hot faster. Another option that we used when we were living as tenants was an electric rod. It costs between 200 to 500 INR and depending upon the wattage heats up water fast - a

Design Patterns : Composite Design Pattern

2010-02-24T10:42:00.000+05:30

A composite design pattern builds complex objects out of simple objects and itself like a tree structure. Its goal is managing a hierarchy of objects where both leaf objects and composition of other objects conform to a common interface. The client sends a message to the head component. The component declares the interface that various parts of the graph should respect. A leaf is a concrete

Design patterns : Bridge Design Pattern

2010-02-10T17:49:00.000+05:30

Bridge pattern decouples the abstraction from its implementation so that both can vary independently. It is quite similar to the adapter pattern. An adapter pattern makes two unrelated, existing classes work together, when the two participants were not thought to be aware of each other during design. A bridge pattern separates concerns and is chosen at the design level before the creation of

Design patterns : Adapter Design Pattern

2010-02-09T18:11:00.000+05:30

Adapter design pattern converts the interface of a class into another interface that the client expects. It lets the classes work together that otherwise could not because of incompatible interfaces. It wraps the existing class in a compatible interface acceptible to the the client. The actors here are the client - which makes use of an object which implements the target interface, the target is

Design Patterns : Prototype pattern

2010-02-09T14:54:00.000+05:30

The prototype pattern specifies the kind of objects to create using a prototypical instance, and creates new objects by copying the prototype. A clone method is available in the class which can be used to create new objects of the same kind. The pattern consists of a prototype - an interface of the cloneable classes. A ConcretePrototype implements the clone operations and a client actually

Design patterns : Factory Method

2010-02-08T17:40:00.000+05:30

Factory method defines an interface for creating an object, but lets the subclasses decide which class to instantiate. Factory method lets a class defer instantiation to subclasses. Factory method makes the design more customizable and only a little more complicated. Other design patterns require new classes whereas factory method requires only a new operation. Factory method is quite similar

Design patterns : Builder

2010-02-05T18:19:00.002+05:30

The purpose of a builder is to separate the construction process of a complex object from its representation so that the same construction process can be used to create different representations. The participating actors are a "director" which interprets the information and invokes the "builder" to get the object built. The builder creates parts of a complex object each time it is called and

Design patterns : Abstract Factory

2010-02-05T15:22:00.000+05:30

The abstract factory pattern provides an interface for creating families of related or dependent objects without specifying their concrete classes. It encapsulates the possibility of creation of a suite of "products" which otherwise would have required a sequence of "if .. then .. else" statements. The abstract factory has the responsibility for providing creation services for the entire family

Restore grub 2 after windows installation

2010-02-02T23:57:00.000+05:30

Here is the step by step guide to recover Grub 2 (with ubuntu 9.10) after windows install. The steps are different than for recovering Grub 1 (as explained in this post: You will need a LIVE cd if you are going to recover an Ubuntu Box. Boot the system with Live CD (I assume you are using Ubuntu Live CD). Press Alt+F2 and enter gnome-terminal command. And continue typing : $sudo fdisk -l This

Design patterns : Singleton pattern

2010-01-29T17:49:00.000+05:30

Singleton design pattern is required when you want to allow only one instance of the class to be created. Database connections and filesystems are examples where singleton classes might be required. You can also use a singleton class to store variables which need global access - thereby limiting the scope of those variables and keeping the global space variable free. With singleton design

How to get your passport made in simple easy steps.

2010-01-29T17:46:00.000+05:30

Prelude : If you have the time, the patience and the ability to coerce and bribe people efficiently, you can save money by going directly to the passport office and interacting with the peon there. It seems that with good interaction skills, the passport can be had in a weeks time with a bribe of only 1000. Preparation : If you lack the time, then, be prepared to spend around 4K. The list of

Forking Vs. Threading

2010-01-11T17:14:00.003+05:30

What is Fork/Forking?Fork is nothing but a new process that looks exactly like the old or the parent process but still it is a different process with different process ID and having it’s own memory. Parent process creates a separate address space for child. Both parent and child process possess the same code segment, but execute independently from each other.The simplest example of forking is

Gearman with php and mysql

2009-12-25T18:17:00.003+05:30

In the earlier post we learned how to push jobs from the client to the worker. What we will try to do here is to use php script - the same worker we developed last time to process queries in the mysql server. That is to use gearman to process requests posted inside mysql client. We would need the mysql UDFs for gearman which could be downloaded from the gearman.org

Using gearman to distribute your work...

2009-12-25T15:44:00.003+05:30

Gearman is a system to farm out work to other machines, dispatching function calls to machines that are better suited to do work, to do work in parallel, to load balance lots of function calls, or to call functions between languages.How does gearman work? Well, a gearman powered app consists of a client, a worker and a job server. The client creats a job and sends it to the job server. The job

Sql Antipatterns Strike Back

2009-12-10T12:34:00.001+05:30

SQL Antipatterns strike back by Bill KarwinSql Antipatterns Strike BackView more documents from Karwin Software Solutions LLC.

Using ssh tunneling to tunnel your browser requests.

2009-12-09T13:35:00.002+05:30

You will need :A ssh server - a machine with access to the net which has ssh server installed on it. We will use this server to forward our requests. You should have access to the server.A ssh client - installed on your machine.A web browser - preferably firefox or internet explorer. Most basic browsers do not support socks proxy.creating the tunnel :The way to create the tunnel isssh -D 8888 <

A brief on using amazon web services.

2009-11-29T14:56:00.003+05:30

Recently we decided to use aws for doing some benchmarks. Why - it is cheaper than getting a system, setting them up and configuring them. But using aws for a long time may prove costly.So, i went to http://aws.amazon.com and signed up with the service. You need to provide a valid credit card no and your phone no before the services are activated. The UI is quite confusing and at times you are

permutation & combination

2009-11-25T09:48:00.001+05:30

Definition: Permutation: An arrangement is called a Permutation. It is the rearrangement of objects or symbols into distinguishable sequences. When we set things in order, we say we have made an arrangement. When we change the order, we say we have changed the arrangement. So each of the arrangement that can be made by taking some or all of a number of things is known as

GPG Error: ... : NO_PUBKEY D739676F7613768D

2009-11-22T17:01:00.002+05:30

You run an apt-get update and it gives some errors which are difficult to comprehend. The output looks some like thisFetched 924B in 2s (352B/s)W: GPG error: http://ppa.launchpad.net karmic Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY D739676F7613768DW: GPG error: http://ppa.launchpad.net karmic Release: The following signatures

Bombay & Delhi - very precise article describing both...

2009-11-10T12:15:00.003+05:30

He is a large amiable boy who smiles at breasts as if they are acquaintances. He suspects he is good looking, and he probably is, especially when he is quiet. A pretty white girl walks into this London pub and he nudges the elbow of a friend. As his eyes follow her to the far corner, his face assumes a sudden seriousness. He then takes her pictures with his phone camera. He tries to meet the eyes

Installing mogilefs for dummies

2009-10-31T12:32:00.002+05:30

MogileFS is an open source distributed filesystem created by Danga Interactive to be used by LiveJournal project. Its features includeNo single point of failureAutomatic file replication - satisfying the number of replica counts specified in the configurationFlat namespace - Files are identified by named keys in a flat, global namespace. You can create as many namespaces as you'd like, so

intro to lucene 2.9

2009-10-06T15:06:00.002+05:30

What crap!!!. Why do they have to come out with a new version every now and then. And make people rewrite their code to upgrade to a new version. How much do they still have to improve their code. Just because of their frequent upgrades, i have to change my code every now and then. Why should i upgrade to lucene 2.9?To answer this question - it could be said that you build something and then you

SHOW ENGINE INNODB STATUS;

2009-10-02T16:10:00.005+05:30

Innodb monitors show information about innodb internal status - which could be used for performance tuning. Lets break down the output of show engine innodb status and get a look at what is happening and how it can be improved. Just fire the "Show engine innodb status" command and check the Output.mysql> show engine innodb status\G*************************** 1. row ***************************

innodb configuration and optimization

2009-09-19T15:54:00.002+05:30

Just thought i should have a quick guide for configuring an optimized for innodb my.cnfuse innodb_data_home_dir & innodb_data_file_path to specify the location and size of the tablespace. innodb_data_home_dir = /path/to/datainnodb_data_file_path = ibdata1:50M;ibdata2:50M:autoextend:max:10Ginnodb_autoextend_increment = 10This asks innodb to create two files ibdata1 & ibdata2 (as tablespace) and

mad world - tears for fears

2009-09-08T22:38:00.003+05:30

All around me are familiar facesWorn out places, worn out facesBright and early for their daily racesGoing nowhere, going nowhereTheir tears are filling up their glassesNo expression, no expressionHide my head I want to drown my sorrowNo tommorow, no tommorowAnd I find it kind of funny, I find it kind of sadThe dreams in which Im dying are the best I've ever hadI find it hard to tell you, I find

moniter and improve lucene search

2009-09-07T20:30:00.002+05:30

How ? Simple - use lucidgaze available at http://www.lucidimagination.com/Downloads/LucidGaze-for-LuceneWith lucidgaze you could analyzeRead/write stats on index utilization, distribution and throughputQuery efficiency stats - show how effectively user input is analyzed and decomposed for processing by the indexMapping of tokenizers, token-streams and analyzers - makes transparent how text is

DB Basics : Types of joins

2009-09-02T12:36:00.004+05:30

Join TypesSo, you have designed a normalized database design for your application. Maybe up to the 3rd normal form. And now, when you need to run queries, you would need to join the tables in the query to get the required information. There has to be some common data that allow those tables to be connected in some meaningful way. Although it’s possible to have more than one common column between

ext4 filesystem

2009-08-24T21:34:00.004+05:30

ext4 is the next "version" of filesystem after ext3. It was released with linux kernel version 2.6.28 which comes with ubuntu 9.04 (Jaunty).Benefits of ext4 over ext3Bigger filesystem and file sizes : ext3 supports 16TB of filesystem size and max file size of 2TB. And ext4 supports 1EB (10^18 bytes = 1024*1024 TB) of filesystem size and max file size of 16TB. Though you would never come across

Eyes!!!

2009-08-15T13:17:00.004+05:30

Jai parked his old yellow bajaj priya scooter in the college's parking lot and took out his polythene containing his books. Since college, he had abandoned taking his books in bags. Bags are for school boys, not for college going big boys. He used to carry a single notebook and a pen in his polybag - simply to scribble during the lectures. He looked at his watch - it was already 11 AM and the

Document oriented data stores

2009-08-11T17:32:00.005+05:30

A document oriented database or data store does not use tables for storing data. It stores each record as a document with certain characteristics. So a multiple documents in this type of store can have different characteristics - which means different number of fields per record and different fields per row. The benefit would be that if you are using a document oriented database for storing a

Why should we watch movies at home

2009-08-08T23:28:00.005+05:30

Because movies@home are free - thanks to piracyYou do not have to adjust your schedule according to the movie timings. The movie timings adjusts to your scheduleYou do not have to drive all the way to the movie hallYou do not have to search for parking and even pay for itYou do not have to stand in queue for ticketsIn case you had not booked the tickets in advance, you do not have to get

12 Angry Men

2009-08-05T09:51:00.004+05:30

I am referring to the movie 12 Angry Men [imdb rating 8.9]. I keep on searching and downloading movies which suit my fancy - mostly horror, comedy, action, thrillers. Lots of times when i had been to the top 250 list on imdb, i had seen this movie at the top. Also when i had searched for top movies, this was on the list.But when i read about the plot and the synopsis of the movie - it told me

Brain vs GF

2009-07-28T09:07:00.001+05:30

BRAIN Vs GF No prices for guessing who won at last. Nice one..........*Akash was waiting for his love ...."30 minutes late!!", his brain shouted at him, "Last time you were 5 mins late and she had literally gobbled u up ... remember??""Yeah yeah", he said to his brain, "You know her ... all moody and stuff .... oh there she is""Scold her OK?", his brain adviced."OK I will try"Sweet Sheetal comes

bill gates in 2nd grade

2009-07-27T21:41:00.001+05:30

A note from Bill Gates' second grade teacher:Billy has been having some trouble behaving in class lately... Last Monday he horded all of the crayons and refused to share, saying that he needed all 160 colors to maximize his 'innovation'. He then proceeded to sell little pieces of paper ("End-User License Agreement for Crayons" he called them) granting his classmates the 'non-transferable right'

Leh Road Trip Saga - kargil to kashmir to delhi

2009-07-18T14:09:00.005+05:30

Disclaimer : The dialogues and characters may be mismatched. Any irregularities are pure co-incidential. There might be some dialogues and scenes to make the tale more spicy.The road from Kargil to srinagar was terrible. All broken up - muddy and gravel. At times we were doing less than 10 Kmph. It seemed that we would be on this road for ever. We crossed Drass - the second coldest inhibited

Leh Road Trip SAGA - Leh to khardung la and to kargil

2009-07-18T11:33:00.006+05:30

Disclaimer : The dialogues and characters may be mismatched. Any irregularities are pure co-incidential. There might be some dialogues and scenes to make the tale more spicy.Next day we decided to tough the highest motorable road in the world - khardung la. We left at around 7 and drove at an easy pace. Everyone seemed tired even after a night's sound sleep.R : Should we do nubra valley? We can

The Leh Road Trip Saga - leh to pangong lake and back

2009-07-15T10:32:00.005+05:30

We checked in our hotel and the slept the whole day. Hotel Manager: Sir, there is hot water. Come down and have some tea, once you are ready. You were supposed to be here last night. J : We got stuck at tanglangla. Please take the luggage to our room. We would like you to arrange for permits to pangong and nubra valley.(We had done some research and knew that permits were required to visit these

The Leh Road Trip SAGA - Keylong to Leh

2009-07-08T09:42:00.010+05:30

Disclaimer : The dialogues and characters may be mismatched. Any irregularities are pure co-incidential. There might be some dialogues and scenes to make the tale more spicy.We leave keylong and proceed towards Jispa. Jispa is beautiful. It only has hotels - no shops or anything. There is the highway - on one side of the highway there are hotels and on the other side is the river with a huge sand

The Leh Road Trip SAGA - Rohtang to Keylong

2009-07-07T17:41:00.005+05:30

By the time we crossed Rohtang, we were tired, exhausted, cold and hungry. It was around 3 in the afternoon and we had not had any lunch. Our originial plan was to reach Sarchu by evening. But covering round about 200 kms on hill in 3-4 hours looked difficult. Another option was a good government resort - The Chandra Bagha at Keylong (around 115 kms from manali) and Hotel IBEX at jispa (140 kms

The Leh Road Trip SAGA - The journey begins

2009-07-04T12:39:00.004+05:30

We all packed our bags with loads of stuff for the 10 day long trip. On 19, i called up the driver again and got the response that he has well rested and would be able to make the journey to leh today eve. At 4 in the evening, i called the driver again and he told me that he is at nehru place and would be here in 15-20 minutes. Finally he arrived here at 5 pm. We all packed our bags inside the

The Leh Road Trip SAGA - Prologue & Preparation

2009-07-02T11:16:00.003+05:30

Prologue:I have been itching to go to Leh on my bike since i bought my bullet around 4 years ago. The problem was that it was difficult to find anyone to accompany me - out of my friend list ofcourse. Around 3-4 months ago - a friend of mine suggested a bike trip that he was trying to materialize. But after trying for a month or so, he finally gave up. But this news had upped my spirits and hopes

optimizing mysql guide

2009-06-11T10:25:00.003+05:30

I had written about this but mostly in parts. Here is a step by step guide to optimizing mysql. Following variables should be looked into for optimizing mysql.Memory consumption: Total memory consumption should be less than the available RAM. You should also leave a small amount of memory for the OS. Total memory consumption can be calculated using this formula (for myisam tables):Key_buffer + (

Trying out windows 7

2009-06-05T10:00:00.002+05:30

So, you have windows xp and linux (preferably ubuntu) installed on your system. And you did not install windows vista because it has issues with running some games and also because it is a resource hog. It chews on your resources until none is left. Well, you saw windows 7, you read its reviews and you figured out that maybe you should try windows 7. Here is a how-to of how i went about

creating opportunity

2009-05-26T09:41:00.002+05:30

If opportunity does not knock on the door, open the door and drag the opportunity inside...

mount linux drive on windows

2009-05-23T10:39:00.004+05:30

Earlier there used to be a software known as explore2fs which used to allow the users to scan all file-systems in read-only mode and copy files from the linux drive to windows. I had used it long time ago...Now-a-days things have changed quite a lot. When i googled for mount ext3 file system on windows, i got tons of links and tons of tools. For some time i was confused how to go about all of it.

The other Stall

2009-05-11T13:50:00.001+05:30

This could happen to you tooo.........I was barely sitting down when I heard a voice from the other stall saying:'Hi, how are you?'I'm not the type to start a conversation in the restroom. I don't know what got into me, but I answered, somewhat embarrassed, 'Doin' just fine!'And the other person says:'So what are you up to?'What kind of question is that? At that point, I'm thinking this is too

How facebook stores billions of photos?

2009-05-01T13:14:00.004+05:30

The new photo infrastructure merges the photo serving tier and storage tier into one physical tier. It implements a HTTP based photo server which stores photos in a generic object store called Haystack. The main requirement for the new tier was to eliminate any unnecessary metadata overhead for photo read operations, so that each read I/O operation was only reading actual photo data (instead of

Prince Of Persia

2009-04-30T20:02:00.001+05:30

Screen shot from Prince Of Persia 2008

Oblivion

2009-04-30T20:00:00.002+05:30

Screenshot from Oblivion - The Elder Scrolls IV

My hunt for air conditioner

2009-04-30T18:00:00.003+05:30

It was monday in mid april. We were running our cooler at full speed. But it was still throwing out hot air. I tried sleeping but the heat was too much to bear. Even the bed was hot and the pillows were wet with sweat. That was the time when i decided that i should be going for an ac. Air conditioning is essential for a good night sleep in india.

Linux to the rescue

2009-04-13T10:01:00.002+05:30

memcached replication

2009-04-07T20:01:00.005+05:30

Wow... finally a solution that provides replication in memcache - repcached.You can have a look at it repcached.lab.klab.org.They provide two types of packages1. a pached memcache source, which can be directly compiled.2. a patch which can be applied to the memcache source and then compiled.So, i downloaded the memcached-(version)-repcached-(version).tar.gz source and simply compiled it../

How my car was mowed down by a truck...

2009-04-02T19:15:00.000+05:30

Actually my car was not mowed down, but it was damaged badly. This is a delayed post. The incident happened on March 08.What happened was that i had gone with my friends and my wife to jaipur. And on the way back, we were in peak traffic. After driving for around 250 kms, We were around 2 kms from home and we were standing at a red light. There was a truck (not the big one, just a small one) on

parking

2009-04-01T10:10:00.003+05:30

Jaipur - the pink city

2009-03-13T17:00:00.004+05:30

Why is jaipur known as the pink city - cause all houses there are colored pink. I had the opportunity of visiting jaipur this on 7th & 8th of this month (March 2009). We started early from New Delhi (Indirapuram to be specific) - around 6 am. We had thought that we will start at 5 but we got delayed. If we had started earlier, we might have got lesser traffic and lesser trucks.The NH8 passing

VIM improvements

2009-02-20T14:32:00.004+05:30

If you have vim 7.x version, you should know that vim supports auto completion for certain languages like c, php, python, html, css, xml, javascript.To enable autocompletion in vim, you need to create a file in your home directory$ vim ~/.vimrcCopy the following code into this fileautocmd FileType python set omnifunc=pythoncomplete#Completeautocmd FileType javascript set omnifunc=

upgrade nvidia drivers on ubuntu 8.10

2009-02-12T09:33:00.003+05:30

So, you have an nvidia graphics card and you want to enjoy the high resolution and smooth graphics that comes with nvidia. You want to see the eye-candy graphics on kde 4.2. Firstly when you install ubuntu, you might not get the nvidia drivers enabled by default. So get and install the default driver available with your ubuntu version install "envyng".$ sudo apt-get install envyng-qtNow this is

installing flash player on ubuntu 64 bit

2009-02-12T09:05:00.003+05:30

Basically you can install flash player on a 32 bit ubuntu machine by using apt$ sudo apt-get install flashplugin-nonfreeIt downloads and installs flash player. And all you have got to do in restart firefox.The issue I faced was how to install flash player on a 64 bit ubuntu machine. As far as i am aware there is no stable release of any flash player for a 64 bit machine. The only way to make the

mount iso image in ubuntu without burning them to disk

2009-02-10T13:58:00.002+05:30

Another thing that could be done in linux is that you can mount the ISO image of any CD and browse/work on it. Following are the simple commands which help you achieve itsuppose you have a downloaded kubuntu-8.10-desktop-amd64.iso, and you want to check its contents.jayant@localhost:~/$ sudo mkdir /tmp/kubuntujayant@localhost:~/$ sudo mount kubuntu-8.10-desktop-amd64.iso /tmp/kubuntu -t iso9660 -

AVL Search Tree

2009-01-14T13:55:00.013+05:30

With BST the problem is that it should be balanced properly so that the height of a tree with node n should be log(2)n. But since BST does not have any balancing algorithm which re-balances the tree on every insert/delete, the tree becomes unbalanced. In this case the height of the tree may go up to n (same as the number of elements n). So the worst case scenario for search is O(n) for a BST.An

Binary Search Tree

2009-01-07T12:07:00.005+05:30

In a tightly packed binary search tree you need at max log(2)n comparisons to find a match for n elements. So, for example to search a list of 1000 elements, you should need max 10 comparisons. Additions and deletions from the BST (binary search tree) require that the sorted order of elements should be maintained.Let us see some pseudo code for creating and maintaining binary search treesFind an

Traversing binary trees

2009-01-03T12:12:00.005+05:30

What are trees? Trees are data structures which contain a node and one or more children. A binary tree is a tree in which each node is either empty or contains at max two children.A binary tree...root --------> R / \ L R / \ / \ l r rl A binary tree of height h<=0 has at max 2^h+1 - 1 nodes. And the height of the tree h = log2(n

Priority Queue & Heapsort

2008-12-30T12:54:00.008+05:30

A priority queue is a queue where each item has a priority associated with it. And the item with the highest priority is at the top of the queue. So, you will be removing the highest priority items from the queue first.A priority queue can be implemented using a heap where the heap is implemented using a complete binary tree. A complete binary tree is supposed to have the heap property if the

Recursive algos

2008-12-24T11:04:00.005+05:30

Few recursive algos:Factorial:function factorial(int n){ if ( n==0 ) return 1; else return n*factorial(n-1);}Fibonacci numbers:function fibo(int n){ if( (n==0) || (n==1) ) return 1; else return fibo(n-1)+fibo(n-2);}Greatest common divisor of 2 numbers :function gcd(int x, int y){ if(y == 0) return x; else return gcd(y, x%y);}Tower of Hanoi: Given 3 pegs, one with a set of N disks of

google chrome on linux

2008-12-15T11:27:00.002+05:30

So, you visit http://www.google.com/chrome every other day with the hope that there would be version of chrome for linux out. And everytime you see the "For Windows Vista/XP only", you feel jealous of windows users and you want to ask google guys why they came out with "chrome for windows" before "chrome for linux".Though, we still do not have any official version of chrome for linux, i looked

postgresql replication using slony-I

2008-11-28T14:19:00.003+05:30

As most postgresql users must be knowing, postgresql does not provide any inbuilt replication solution. There are lots of 3rd party replication products available for postgresql. Slony is one of them. Slony is a trigger based replication solution, that is it used triggers to push data to the slave. Slony is supposed to be one of the most stable replication solutions for postgresql.You can

An auto ride in Delhi

2008-11-04T11:11:00.001+05:30

I have been coming back from baroda and it was around 7 AM in the morning. The train was already 2 hours late and would stop at new delhi railway station in some time. I was ready with my backpack. As soon as the train stopped, i got down and proceeded to the exit (Ajmeri gate side) to catch an auto for noida (my residence).As soon as i came to the road outside the station and almost half a

After Death

2008-10-23T11:30:00.005+05:30

HTML / XML Expert...Networking Expert...Programmers...

setting up hadoop

2008-10-18T14:46:00.006+05:30

Hadoop is a distributes file system similar to google file system. It uses map-reduce to process large amounts of data on a large number of nodes. I will give a brief step by step process to set up hadoop on single and multiple nodes.First lets go with a single node: Download hadoop.tar.gz from hadoop.apache.org. You can setup hadoop to work on any user, but it is preferred that you setup a

Whatever....

Postgresql replication

Nginx with php-fpm versus apache with modphp

why and how to overclock your android phone

opcode cache comparison - xcache versus apc versus no-cache

Data structures - TRIE

Strategies for porting data