Articles

Configuring Databricks for Koalas

koala getting hlep from a Firefighter

The Apache Spark open source organization maintains all of the documentation for Apache Spark, which is a set of APIs which are used in Databricks and other big data processing applications.  The documentation provides the detailed information about the libraries, but the instructions for loading libraries in Databricks are not exactly the same as are used in Databricks, so if you follow the Spark installation instructions, you will get nowhere. If you follow the steps listed you will be up and running in no time.

Installing Options – Cluster or Notebook ?

If you are not using a ML workspace you can add in using dbutils like this.
dbutils.library.installPyPI("koalas")
dbutils.library.restartPython()

Unfortunately if you are using an ML workspace, this will not work and you will get the error message org.apache.spark.SparkException: Library utilities are not available on Databricks Runtime for Machine Learning. The Koalas github documentation  says “In the future, we will package Koalas out-of-the-box in both the regular Databricks Runtime and Databricks Runtime for Machine Learning”.  What this means is if you want to use it now

Most of the time I want to install on the whole cluster as I segment libraries by cluster.  This way if I want those libraries I just connect to the cluster that has them. Now the easiest way to install a library is to open up a running Databricks cluster (start it if it is not running) then go to the Libraries tab at the top of the screen. My cluster is called Yucca, and you can see that it is running because the circle next to the name is green.

After you are on the Libraries table you will see two buttons.  Click on the one labeled Install New.  A window will appear.  Select the library source of PYPI and in the Package text box enter the word koalas.  Then click on the install button.

Install Databricks LibraryThe installation may take a few minutes.  When it is complete you will see a green  status circle and the word installed.

After this you are ready to use the new library, once you import it as shown here.

 

Why do I want to install Koalas in Databricks?

If you have written Python code for Machine Learning, chances are you are using Pandas. Pandas dataframes are practically the standard for manipulating the data in Python.  They are not however part of the Spark API.  While you can move your Python code over to Databricks without making any changes to it, that is not advisable.  Databricks is able to scale pandas, so adding more resources to your code may not improve the performance.  When writing Python code for Databricks you need to use the Spark APIs in order to ensure that your code can scale and will perform optimally.   Prior to April of 2019, that meant that you had to use Spark dataframes and not pandas dataframes, which could involve a bit of rework when porting code as much code was written in pandas.  In April of last year Koalas was added to Spark, meaning that changing code to use a pandas dataframe to a koalas dataframe means that you only have to change one word. Koalas contains all of the functionalities of a pandas dataframe, so if you are familiar with one you can use the other.

More About Koalas

koala getting hlep from a Firefighter

Photo Credit:New York Fox 5

It is impossible for me to load the library without thinking about the Australian Bush Fires which are burning the homes of people and Koalas.  If your finances allow it, please consider donating to the firefighters as I am sure they can use help to save the homes of people and animals in Australia.

 

Regards,

Yours Always

Ginger Grant

Data aficionado et SQL Raconteur

 

Introduction to Databricks

As I have been doing some work on Databricks, I thought that it would make sense that I start writing about it. Databricks is a scalable environment used to run R, Python and Scala code in the cloud. It currently can be run in either AWS or Microsoft’s Azure Cloud. For those of you who are budget-minded when it comes to learning new tools, there is also a free tier, which is available here Community.cloud.databricks.com . It has somewhat limited compute capacity, but if you are just starting out you might find it helpful.

Backstory

Databricks is an implementation of Apache Spark, part of the Hadoop collective and was a replacement for Map Reduce.  Many of the people who worked on that open source project were students at Berkeley, where Apache Spark was created and added to Apache in 2013.  Like many development projects, after it was completed, they had some ideas on how to improve the code.  This time they decided to not make it open source but make it a commercial product so they could make some money for their development efforts. In April of 2017 Databricks was released on AWS and in March 2018 it was released in Azure.

Creating an Azure Databricks Service

Creating a Databricks Service is very straight-forward.  There are only a few things that you need to complete when creating a new Databricks instance. The location becomes very important if you are looking at higher level performing instances which may not be available in all locations. If you are just getting started don’t worry about high level hosting services as you most likely will not need them and most of the compute options are available in most data centers.  As always in Azure you want to make sure that you are hosting your Databricks service in the same location as your data so you will not need to pay to transfer data between data centers.

The Pricing Tier contains three options: Standard, Premium and Trial(Premium 14 Days).  The trial is pretty self-explanatory and is a great way to get started using Databricks. They are of course a few differences between Standard and Premium. Premium has extra features needed for teams including Role-Based rights for the components of Databricks.  And if you want ODBC authentication and Audit logs you will need to use Premium.  For more information on the cost of Databricks pricing tiers, check out Microsoft’s pricing link for more information.

Once you have an instance created, you can start using Databricks.  The application is contained within a managed instance, so once you launch Databricks you will be in their environment, which looks the same as the free edition.

 

Clusters, Notebooks and Data

These three components are the most important parts of Databricks as they include the compute power, where you write code and the information you work with respectively. These components are all separated in Databricks to improve scaling and provide a familiar environment to create and run code.

Cluster

The most important Databrick element, as it contains the compute.  This is also the part of Databricks which will greatly increase your bill as the more resources you use to run code the more money you need to run it.  One nice thing is clusters by default will terminate in 120 minutes of inactivity.  I generally drop this to 20 minutes.  If I am using it naturally it will not terminate, but if I am not using it, I want the charges to stop. You can also automatically spin up clusters to run jobs, so that they will only be in use when the job needs them. More about that in another post.

Notebooks

Databricks Notebook Import

Databricks Notebook Import

There are 3 supported languages in Databricks, R, Scala and Python, and within Databricks all of these languages are written in Notebooks. You don’t have to write your code in the environment.  You can write it locally and then import it. However, if you want to export your Notebook then run it locally, it gets trickier. Natively all of the Notebooks in Databricks are saved as .dbc files.  You can’t read them from anywhere else.  Fortunately there is a workaround to format the Notebook files as .ipynb files which can be read by any notebook.  Dave Wentzel from Microsoft has an elegant solution to convert .dbc to .ipynb which he includes in his blog here.

Data

You have a lot of options with data.  You can import a dataset into your environment to play with or you can connect to just about anything you can think of.  When you start doing data connections is when you stop using the community edition as you will want to use the Azure version to this to connect to various data resources like Azure SQL and blob storage.  More on how to that later in an upcoming post.

If you are interested in hearing more about Databricks and are in Chicago, I am teaching an all day class as part of SQL Saturday Chicago and would love to have you attend. More information on that class is here.

Yours Always

Ginger Grant

Data aficionado et SQL Raconteur

Reviewing Azure Databricks and Data Lake Analytics

Databricks is a recent addition to Azure that is greatly influencing the technology choices that people are making when determining how to process data.  Prior to the introduction of Databricks to Azure in March of 2018, if you had a lot of unstructured data which was stored in HDFS clusters, and wanted to analyze it in a scalable fashion, the choice was Data Lake and using USQL with Data Lake Analytics.  With the introduction of Databricks, there is now a choice for analysis between Data Lake Analytics and Databricks for analyzing data.

Analyzing Data with Data Lake Analytics

Data Lake Analytics offers many of the same features as Databricks.  You can write code to analyze data and the analysis can be automatically parallelized to scale.  Microsoft has released a new version of Data Lake, which they are calling Data Lake Storage Gen2 to improve the performance of analysis performed with Data Lakes.  The difference, between the old version and the new one, is the hierarchical namespace to Azure Blob Storage which provides an indexing capability which means that operations can be performed on a directory rather than enumerating through all of the data.  Data stored within a Data Lake can be accessed just like HDFS and Microsoft has provided a new driver for accessing data in a Data Lake which can be used with SQL Data Warehouse, HDinsight and Databricks.  With Data Lake Analytics, the data analysis is designed to be performed in U-SQL. While it supports R and Python libraries, users of the technology will need to get up to speed on U-SQL which is a lot like C#.  This knowledge needs to be learned. Since U-SQL is so new, only a few years old, there is not a large number of people who are familiar with it.

Analyzing Data with Databricks

When analyzing data with Databricks, there are three different languages which you can use: R, Scala, and Python.  Data can be read in from a variety of different Azure Storage options, including Blob Storage, Data Lake, and by using a JDBC connection. You can also connect to Azure SQL DB, as well as Azure SQL Data Warehouse. Since there are three different languages which can be used, there is no reason to learn a new language as most people are already very familiar with at least one of the three supported languages.

In addition to the ability to develop code, Databricks offers some other features which are not found in Data Lake Analytics.  Many projects anticipate that people are going to be working in teams and will need to have an environment to share code and version it.  This capability is baked into Azure Databricks as it provides an environment for sharing data with others and natively saving the data to a GitHub repository.  The development environment is Jupyter Notebooks which provides a great way to document the code and include data samples, all at the same time.  Databricks also includes a job schedule component so that work created in Databricks can use a native scheduler which has the ability to retry and send configurable messages on error or completion.  These additional features, plus the ability to code in a language which is already widely used in the industry, give Databricks the edge in determining which technology to use going forward.

Yours Always

Ginger Grant

Data aficionado et SQL Raconteur