#prestodb

A weeks ago, Facebook released a new open source project called PrestoDB which they billed as a market improvement over Hive and Hadoop. According to the PrestoDB site, Presto is a real time query engine that supports a SQL like syntax, similar to Hive. However, unlike Hive, Presto doesn’t execute queries using MapReduce jobs but instead uses its own internal distribution mechanism. According to the Presto site and current users, most queries will see an order of magnitude speedup compared to Hive. And the best part? PrestoDB can read metadata from Hive’s metastore and read files off HDFS just like Hive – pretty wild.

Anyway, since I love new toys (who doesn’t!?) I decided to try setting up PrestoDB on Amazon EMR to see how difficult it was and also experience the speedups. Turns out, once you have an Amazon EMR cluster running getting PrestoDB up is almost trivial. Just follow the PrestoDB deploying directions to get yourself situated. Make sure you create *all* the files or you’ll get some necessarily cryptic errors along the way.

The config files I ended up using were:

You’ll need to create the “/mnt/presto” directory and also make it accessible to whatever user you plan to run the daemon under.

The one huge gotcha I ran into was that I couldn’t figure out what port Hive’s Thrift service was running on. For some reason, it’s notably absent from Amazon’s documentation and I couldn’t find the hive-site.xml file on the EMR EC2. Completely randomly, I ran across this manual page from Jaspersoft enumerating which ports different versions of Hive run Thrift on when you use EMR. Turns out, its different per Hive version but 0.11.0 will use 10004.

Once you have everything configured, just follow the docs to start the server and you’ll be ready to query. One thing to note though is that you’ll need to setup PrestoDB manually on the rest of your machines and also enable the discovery service for this to “really” work.

Anyway, happy querying!

Posted In: Big Data

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