Lambda vs Proc Vs Blocks


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The difference between these three is one of the most baffling concepts to grasp while anyone starts to learn ruby. Since at Red Panthers we recruit and build our own team from freshers, we too will be blogging about it here to make it easy for the beginners.

But before we state the difference between the three, let me explain what all these three does to make it easy for you.

Blocks: They are called closures in other languages, it is a way of grouping code/statements. In ruby single line blocks are written in {} and multi-line blocks are represented using do..end

An interesting fact about ruby is that all methods in ruby accept a block, even if you don’t declare a variable to accept it. So for example, take the method below

It can accept a block as below

The code is valid, but the output will have only puts “Hello World”.

Why? because we passed in the block but it is not getting called. To run the block passed within your method you need to use the yield command.

Now it will print

But since we placed yield, it would now be expecting a block to be always passed in. So we need to …

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Optimising PostgreSQL database query using indexes


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At Red Panthers PostgreSQL is our go to database we use it everywhere. So thinking about how to optimize our database performance is one of the most talked about topic at our office. The best way to speed up report generation and data retrieval within a rails application is to leave it to the database, as they have algorithms and optimizations build just for that. We always felt that most Ruby on Rails projects out there, do not use the full potential of a database and they usually just limit it to a data store. PostgreSQL or any database for that matter is much more than that.

We would be blogging on how we use PostgreSQL in our projects to speed up our client’s applications. This particle is the first part of a series of article we would be writing on database optimization.

Database Indexes:

Indexes are a special lookup table that the database search engine can use to speed up data retrieval. An Index is similar to a pointer to a particular row of a table. As a real world example, consider a Britannica Encyclopedia with 22 volumes of books, and an extra book listing  the index,with which you can find out the …

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Database transaction in Rails


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A transaction is a sequence of operations performed as a single logical unit of work. A logical unit of work must exhibit four properties called the atomicity, consistency, isolation and durability (ACID) properties, to qualify as a transaction.

We use database transactions to make sure that all the instructions we send to database are successful, and would cause changes to the database only if they are successful. Let’s say that you are working on a banking application which would withdraw money from one account and deposit into another account. The code for it would look like below

But for some reason, the withdrawal was successful but the deposit was not, the amount was taken out but never deposited to the other user.To avoid these kind of issues, database has a functionality called transactions, in which you can  build up each sql query. But if for any reason, any of the sql statements fails or an exception rises in the block, all the transactions are rolled back to their original form.

In rails, the transaction method is available as class method and instance method, but the functionality for both is same. There is no difference when you will use.

and

The …

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