taupirho / read-file-with-s3-select

How to read a text file on S3 using AWS S3 SELECT

read-file-with-s3-select

How to read a file on S3 using standard SQL

Recently Amazon realeased their S3 Select product on General Availabilty. This is an exciting new tool for data engineers to use so I thought I'd write up an example showing its use. AWS S3 Select is a way for users to query data in-place on Amazon S3. One of its main uses is being able to allow users to get sub-sets of data from S3 without having to download whole - and potentially huge - data files. You should note that S3 Select is intended as a query tool not an analytic tool and as such the SQL statements allowed are limited to SELECT / FROM / WHERE / LIMIT although you can use aggregates such as SUM/MIN/MAX/COUNT/AVG and certain STRING,DATE, CONVERSION and CONDITIONALS functions.

At the time of writing you can only read delimited text files like CSV and JSON text files although these can be in compressed GZIP format

The file I'm querying is the same one I've used in the rest of my series on reading big data files that you can find in my other repositories. This is a 21 Gbyte pipe separated text file containing approx 366 million records. I used python to call the S3 Select API and tested it using an AWS Lambda.