Presto
Last updated
Last updated
is an open source distributed SQL query engine for running interactive analytic queries on data at a large scale. This guide describes how to run queries against Presto with Alluxio as a distributed caching layer, for any data storage systems that Alluxio supports (AWS S3, HDFS, Azure Blob Store, NFS, and more). Alluxio allows Presto access data regardless of the data source and transparently cache frequently accessed data (e.g., tables commonly used) into Alluxio distributed storage. Co-locating Alluxio workers with Presto workers improves data locality and reduces the I/O access latency when other storage systems are remote or the network is slow or congested.
Setup Java for Java 8 Update 161 or higher (8u161+), 64-bit.
. This guide is tested with PrestoDB 0.247.
Alluxio has been set up and is running.
Make sure that the Alluxio client jar is available. This Alluxio client jar file can be found at {{site.ALLUXIO_CLIENT_JAR_PATH}} in the tarball downloaded from Alluxio .
Make sure that Hive Metastore is running to serve metadata information of Hive tables.
Presto gets the database and table metadata information (including file system locations) from the Hive Metastore, via Presto's Hive connector. Here is a example Presto configuration file ${PRESTO_HOME}/etc/catalog/hive.properties, for a catalog using the Hive connector, where the metastore is located on localhost.
In order for Presto to be able to communicate with the Alluxio servers, the Alluxio client jar must be in the classpath of Presto servers. Put the Alluxio client jar {{site.ALLUXIO_CLIENT_JAR_PATH}} into the directory ${PRESTO_HOME}/plugin/hive-hadoop2/ (this directory may differ across versions) on all Presto servers. Restart the Presto workers and coordinator:
Ensure your Hive Metastore service is running. Hive Metastore listens on port 9083 by default. If it is not running, execute the following command to start the metastore:
Create an external Hive table pointing to the Alluxio file location.
View the Alluxio WebUI at http://master_hostname:19999 and you can see the directory and files that Hive creates:
Start your Presto server. Presto server runs on port 8080 by default (configurable with http-server.http.port in ${PRESTO_HOME}/etc/config.properties ):
Run a single query (replace localhost:8080 with your actual Presto server hostname and port):
And you can see the query results from console:
You can also find some of the Alluxio client log messages in the Presto Server log:
Alternatively, add Alluxio properties to the Hadoop configuration files (core-site.xml, hdfs-site.xml), and use the Presto property hive.config.resources in the file ${PRESTO_HOME}/etc/catalog/hive.properties to point to the Hadoop resource locations for every Presto worker.
If the Alluxio HA cluster uses internal leader election, set the Alluxio cluster property appropriately in the alluxio-site.properties file which is on the classpath.
Alternatively you can add the property to the Hadoop core-site.xml configuration which is contained by hive.config.resources.
For example, change alluxio.user.file.writetype.default from default ASYNC_THROUGH to CACHE_THROUGH.
Specify the property in alluxio-site.properties and distribute this file to the classpath of each Presto node:
Alternatively, modify conf/hive-site.xml to include:
Presto's Hive connector uses the config hive.max-split-size to control the parallelism of the query. For Alluxio 1.6 or earlier, it is recommended to set this size no less than Alluxio's block size to avoid the read contention within the same block. For later Alluxio versions, this is no longer an issue because of Alluxio's async caching abilities.
It is recommended to increase alluxio.user.streaming.data.timeout to a bigger value (e.g 10min) to avoid a timeout failure when reading large files from remote workers.
After completing the basic configuration, Presto should be able to access data in Alluxio. To configure more advanced features for Presto (e.g., connect to Alluxio with HA), please follow the instructions at .
Here is an example to create an internal table in Hive backed by files in Alluxio. You can download a data file (e.g., ml-100k.zip) from . Unzip this file and upload the file u.user into /ml-100k/ in Alluxio:
Follow to download the presto-cli-<PRESTO_VERSION>-executable.jar, rename it to presto, and make it executable with chmod +x (sometimes the executable presto exists in ${PRESTO_HOME}/bin/presto and you can use it directly).
To configure additional Alluxio properties, you can append the conf path (i.e. ${ALLUXIO_HOME}/conf) containing to Presto's JVM config at etc/jvm.config under Presto folder. The advantage of this approach is to have all the Alluxio properties set within the same file of alluxio-site.properties.
For information about how to connect to Alluxio HA cluster using Zookeeper-based leader election, please refer to .
When you see error messages like the following, it is likely that Alluxio client jar is not on the classpath of the Presto worker. Please follow to fix this issue.
