Category: Spark

We recently implemented a Spark streaming application, which consumes data from from multiple Kafka topics. The data consumed from Kafka comprises different types of telemetry events generated by mobile devices. We decided to host the Spark cluster using the Amazon EMR service, which manages a fleet of EC2 instances to run our data-processing pipelines.
As part of preparing the cluster and application for deployment to production, we needed to implement monitoring so we could track the streaming application and the Spark infrastructure itself. At a high level, we wanted ensure that we could monitor the different components of the application, understand performance parameters, and get alerted when things go wrong.
In this post, we’ll walk through how we aggregated relevant metrics in Datadog from our Spark streaming application running on a YARN cluster in EMR.

Check it out. If this is interesting, Priya’s blog has the full series.

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Pivoting With Spark SQL

Published 2018-11-06 by Kevin Feasel

MaryAnn Xue shows us how to use the PIVOT operator in Spark SQL:

Pivot was first introduced in Apache Spark 1.6 as a new DataFrame feature that allows users to rotate a table-valued expression by turning the unique values from one column into individual columns.
The upcoming Apache Spark 2.4 release extends this powerful functionality of pivoting data to our SQL users as well. In this blog, using temperatures recordings in Seattle, we’ll show how we can use this common SQL Pivot feature to achieve complex data transformations.

The syntax is quite similar to the PIVOT syntax that SQL Server uses.

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Logistic Regression With Apache Spark

Published 2018-11-05 by Kevin Feasel

Manoj Gautam shows how to perform a logistic regression with Apache Spark:

Since we are going to try algorithms like Logistic Regression, we will have to convert the categorical variables in the dataset into numeric variables. There are 2 ways we can do this.
Category Indexing
One-Hot Encoding
Here, we will use a combination of StringIndexer and OneHotEncoderEstimator to convert the categorical variables. The OneHotEncoderEstimator will return a SparseVector.

Click through for the code and explanation.

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Change Data Capture With Databricks Delta

Published 2018-10-31 by Kevin Feasel

Ameet Kini and Denny Lee show how to use Databricks Delta to handle change data capture from different processes:

With Databricks Delta, the CDC pipeline is now streamlined and can be refreshed more frequently: Informatica => S3 => Spark Hourly Batch Job => Delta. In this scenario, Informatica writes change sets directly to S3 using Informatica’s Parquet writer. Databricks jobs run at the desired sub-nightly refresh rate (e.g., every 15 min, hourly, every 3 hours, etc.) to read these change sets and update the target Databricks Delta table.
With minor changes, this pipeline has also been adapted to read CDC records from Kafka, so the pipeline there would look like Kafka => Spark => Delta. In the rest of this section, we elaborate on this process, and how we use Databricks Delta as a sink for their CDC workflows.
With one of our customers, we implemented these CDC techniques on their largest and most frequently refreshed ETL pipeline. In this customer scenario, Informatica writes a change set to S3 for each of its 65 tables that have any changes every 15 minutes. While the change sets themselves are fairly small (< 1000 records), their target tables can become quite large. Out of the 65 tables, roughly half a dozen are in the 50m-100m row range, and the rest are smaller than 50m. In Oracle, this pipeline would have run every 15 minutes, keeping in sync with Informatica. In Databricks Delta, we thought this would take close to an hour due to S3 latencies but ended up being pleasantly surprised with a 30 and even 15-minute refresh period depending on cluster size.

Click through for the rest of the story.

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Using IO Cache To Speed Up Spark Jobs

Published 2018-10-30 by Kevin Feasel

Chris Seferlis looks at what the HDInsight team has done to speed up Apache Spark jobs:

The big news here is the recently released preview of HDInsight IO Cache, which is a new transparent data caching feature that provides customers with up to 9X performance improvement for Spark jobs, without an increase in costs.
There are many open source caching products that exist in the ecosystem: Alluxio, Ignite, and RubiX to name a few big ones. The IO Cache is also based on RubiX and what differentiates RubiX from other comparable caching products is its approach of using SSD and eliminating the need for explicit memory management. While other comparable caching products leverage the reservation of operating memory for caching the data.

Read on for more details.

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Spark Streaming On Azure Databricks

Published 2018-10-25 by Kevin Feasel

Tristan Robinson shows us how to run Spark Streaming within Azure Databricks:

Real-time stream processing is becoming more prevalent on modern day data platforms, and with a myriad of processing technologies out there, where do you begin? Stream processing involves the consumption of messages from either queue/files, doing some processing in the middle (querying, filtering, aggregation) and then forwarding the result to a sink – all with a minimal latency. This is in direct contrast to batch processing which usually occurs on an hourly or daily basis. Often is this the case, both of these will need to be combined to create a new data set.
In terms of options for real-time stream processing on Azure you have the following:

Azure Stream Analytics
Spark Streaming / Storm on HDInsight
Spark Streaming on Databricks
Azure Functions

Click through for more.

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Big Data Clusters In SQL Server 2019

Published 2018-10-23 by Kevin Feasel

James Serra lays out some of the architecture behind SQL Server 2019 Big Data Clusters:

While extract, transform, load (ETL) has its use cases, an alternative to ETL is data virtualization, which integrates data from disparate sources, locations, and formats, without replicating or moving the data, to create a single “virtual” data layer. The virtual data layer allows users to query data from many sources through a single, unified interface. Access to sensitive data sets can be controlled from a single location. The delays inherent to ETL need not apply; data can always be up to date. Storage costs and data governance complexity are minimized. See the pro’s and con’s of data virtualization via Data Virtualization vs Data Warehouse and Data Virtualization vs. Data Movement.
SQL Server 2019 big data clusters with enhancements to PolyBase act as a virtual data layer to integrate structured and unstructured data from across the entire data estate (SQL Server, Azure SQL Database, Azure SQL Data Warehouse, Azure Cosmos DB, MySQL, PostgreSQL, MongoDB, Oracle, Teradata, HDFS, Blob Storage, Azure Data Lake Store) using familiar programming frameworks and data analysis tools:

James covers some of the reasoning behind this and the shift from using Polybase to integrate data with Hadoop + Azure Blob Storage to using SQL Server as a data virtualization engine.

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Looking At Databricks Cluster Pricing

Published 2018-10-19 by Kevin Feasel

Tristan Robinson takes a look at Azure Databricks pricing:

The use of databricks for data engineering or data analytics workloads is becoming more prevalent as the platform grows, and has made its way into most of our recent modern data architecture proposals – whether that be PaaS warehouses, or data science platforms.
To run any type of workload on the platform, you will need to setup a cluster to do the processing for you. While the Azure-based platform has made this relatively simple for development purposes, i.e. give it a name, select a runtime, select the type of VMs you want and away you go – for production workloads, a bit more thought needs to go into the configuration/cost. In the following blog I’ll start by looking at the pricing in a bit more detail which will aim to provide a cost element to the cluster configuration process.

There are a few complicating factors in figuring out cluster price but rest assured that it will be costly.

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Data Science And Data Engineering In HDP 3.0

Published 2018-10-17 by Kevin Feasel

Saumitra Buragohain, et al, show off some of the things added to the Hortonworks Data Platform for data scientists and data engineers:

We leverage the power of HDP 3.0 from efficient storage (erasure coding), GPU pooling to containerized TensorFlow and Zeppelin to enable this use case. We will the save the details for a different blog (please see the video)- to summarize, as we trained the car on a track, we collected about 30K images with corresponding steering angle data. The training data was stored in a HDP 3.0 cluster and the TensorFlow model was trained using 6 GPU cards and then the model was deployed back on the car. The deep learning use case highlights the combined power of HDP 3.0.

Click through for more additions and demos.

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SparkSession Versus SparkContext

Published 2018-10-12 by Kevin Feasel

Abhishek Baranwal explains the differences between the SparkSession object and the SparkContext object when writing Spark code:

Prior to spark 2.0, SparkContext was used as a channel to access all spark functionality. The spark driver program uses sparkContext to connect to the cluster through resource manager.
SparkConf is required to create the spark context object, which stores configuration parameters like appName (to identify your spark driver), number core and memory size of executor running on worker node.
In order to use API’s of SQL, Hive, and Streaming, separate context needs to be created.

Read on to see where SparkSession fits in.

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