Node Properties

The node properties file, /etc/presto/node.properties, contains configuration specific to each node. A node is a single installed instance of Presto on a machine. This file is typically created by the deployment system when Presto is first installed. The following is a minimal node.properties:

node.environment=production
node.id=ffffffff-ffff-ffff-ffff-ffffffffffff
node.data-dir=/var/presto/data

The above properties are described below:

• node.environment: The name of the environment. All Presto nodes in a cluster must have the same environment name.
• node.id: The unique identifier for this installation of Presto. This must be unique for every node. This identifier should remain consistent across reboots or upgrades of Presto. If running multiple installations of Presto on a single machine (i.e. multiple nodes on the same machine), each installation must have a unique identifier.
• node.data-dir: The location (filesystem path) of the data directory. Presto will store logs and other data here.

JVM Config

The JVM config file, /etc/presto/jvm.config, contains a list of command line options used for launching the Java Virtual Machine. The format of the file is a list of options, one per line. These options are not interpreted by the shell, so options containing spaces or other special characters should not be quoted (as demonstrated by the OnOutOfMemoryError option in the example below).

The following provides a good starting point for creating jvm.config:

-server
-Xmx16G
-XX:+UseConcMarkSweepGC
-XX:+ExplicitGCInvokesConcurrent
-XX:+AggressiveOpts
-XX:+HeapDumpOnOutOfMemoryError
-XX:OnOutOfMemoryError=kill -9 %p

Because an OutOfMemoryError will typically leave the JVM in an inconsistent state, we write a heap dump (for debugging) and forcibly terminate the process when this occurs.

Config Properties

The config properties file, /etc/presto/config.properties, contains the configuration for the Presto server. Every Presto server can function as both a coordinator and a worker, but dedicating a single machine to only perform coordination work provides the best performance on larger clusters.

The following is a minimal configuration for the coordinator:

coordinator=true
node-scheduler.include-coordinator=false
http-server.http.port=8080
task.max-memory=1GB
discovery-server.enabled=true
discovery.uri=http://example.net:8080

And this is a minimal configuration for the workers:

coordinator=false
http-server.http.port=8080
task.max-memory=1GB
discovery.uri=http://example.net:8080

Alternatively, if you are setting up a single machine for testing that will function as both a coordinator and worker, use this configuration:

coordinator=true
node-scheduler.include-coordinator=true
http-server.http.port=8080
task.max-memory=1GB
discovery-server.enabled=true
discovery.uri=http://example.net:8080

These properties require some explanation:

• coordinator: Allow this Presto instance to function as a coordinator (accept queries from clients and manage query execution).
• node-scheduler.include-coordinator: Allow scheduling work on the coordinator. For larger clusters, processing work on the coordinator can impact query performance because the machine’s resources are not available for the critical task of scheduling, managing and monitoring query execution.
• http-server.http.port: Specifies the port for the HTTP server. Presto uses HTTP for all communication, internal and external.
• task.max-memory=1GB: The maximum amount of memory used by a single task (a fragment of a query plan running on a specific node). In particular, this limits the number of groups in a GROUP BY, the size of the right-hand table in a JOIN, the number of rows in an ORDER BY or the number of rows processed by a window function. This value should be tuned based on the number of concurrent queries and the size and complexity of queries. Setting it too low will limit the queries that can be run, while setting it too high will cause the JVM to run out of memory.
• discovery-server.enabled: Presto uses the Discovery service to find all the nodes in the cluster. Every Presto instance will register itself with the Discovery service on startup. In order to simplify deployment and avoid running an additional service, the Presto coordinator can run an embedded version of the Discovery service. It shares the HTTP server with Presto and thus uses the same port.
• discovery.uri: The URI to the Discovery server. Because we have enabled the embedded version of Discovery in the Presto coordinator, this should be the URI of the Presto coordinator. Replace example.net:8080 to match the host and port of the Presto coordinator. This URI must not end in a slash.

Log Levels

The optional log levels file, /etc/presto/log.properties, allows setting the minimum log level for named logger hierarchies. Every logger has a name, which is typically the fully qualified name of the class that uses the logger. Loggers have a hierarchy based on the dots in the name (like Java packages). For example, consider the following log levels file:

com.facebook.presto=INFO

This would set the minimum level to INFO for both com.facebook.presto.server and com.facebook.presto.hive. The default minimum level is INFO (thus the above example does not actually change anything). There are four levels: DEBUG, INFO, WARN and ERROR.

Catalog Properties

Presto accesses data via connectors, which are mounted in catalogs. The connector provides all of the schemas and tables inside of the catalog. For example, the Hive connector maps each Hive database to a schema, so if the Hive connector is mounted as the hive catalog, and Hive contains a table clicks in database web, that table would be accessed in Presto as hive.web.clicks.

Catalogs are registered by creating a catalog properties file in the /etc/presto/catalog directory. For example, create /etc/presto/catalog/jmx.properties with the following contents to mount the jmx connector as the jmx catalog:

connector.name=jmx

See Connectors for more information about configuring connectors.