Aggregate using Python Spark (pyspark)

Finally I am getting hands on with data processing and here I am posting a simple aggregate task using Python Spark. The task is to calculate the aggregate spend by customer and display the data in sorted order. Aggregation is a simple reduce job on the key value pairs of customer ID and each individual spend. 

 Spark provides sorting by key [sortByKey()] out of the box, but to sort by value, one needs to provide a lambda to the more generic sortBy() function. 

Comments

Post a Comment

Popular posts from this blog

Connect to MySQL 5.7 from Python using SSL

In the previous blog we saw how to connect to MySQL Server 5.7 from PHP using SSL. In this entry I will describe the steps I took to connect to MySQL Server 5.7 from Python code. I used mysql-connector as the Python library. The default install (version 2.2.3) failed, so I had to install the previous version (v. 2.1.6). sudo pip install mysql-connector==2.1.6 The code to connect using Python is similar to PHP with similar parameters which have to be set. I did run into a few issues with my query not getting parsed if I passed query parameters as parameters. So I had to prepare the whole query and send it as a single complete query with no parameters in the 'execute' function. Below is my piece of working code. As I went further and tried to put data fetched from WoW API, I faced further problems with text encoding. I also had problems with creating multi line queries. I could not find a lot of discussion material on Stackoverflow. I found out though that Python 2...
Read more

Performance improvement of MySQL inserts in Python using batching

In this blog entry we will see how much performance improvement we can get by using batching for inserts in MySQL 5.7 from a Python3 client. In this example the number of rows to be inserted is around 140K. The json blob for this data has a size of around ~25MB. First we will insert them one by one. Note even in this case, I am inserting all of them and finally doing a single commit. The default behavior of the mysql-connector library is that autocommit is false. This is good for performance. If we commit after each insert, the performance will be even worse. Below are the code and performance details. Number of auctions: 139770 Number of rows affected : 139770 Time taken for insert: 34.17 s For my use case, I was okay with around 30 seconds of insert time for the bulk update, but thought of trying out the batch insert. I ran into a problem because of the default max packet size for MySQL execute statements. I had to change it in my.cnf file by adding max packet siz...
Read more

Connect to MySQL Server 5.7 from PHP 7.0 using SSL

It took me from late morning to evening to be able to connect to MySQL Server 5.7 from PHP 7.0 over SSL on an EC2 machine with Amazon Linux OS image. There were many steps and each had its own challenge. Below I am mentioning the steps and how I worked around the problems. Step 1: Upgrading PHP from 5.6 to 7.0. First one has to remove the existing version of PHP and then install a newer version. I tried installing version 7.1 first but I ran into dependency issues like libpng15 for which the easiest way to install is to build from source. To avoid falling into this dependency cycle, I tried installing version 7.0 and this one installed smoothly. # Remove PHP 5.6 [ec2-user@ ~]$ sudo yum remove php5* # Install PHP 7.0 [ec2-user@ ~]$ sudo yum install php70 php70-mysqlnd php70-imap php70-gd \ php70-pecl-memcache php70-pecl-apcu Step 2: Upgrading MySQL server from 5.6 to 5.7. The default repos did not have MySQL 5.7. I also could not install it by adding repos, as ev...
Read more