druid/docs/querying/sql-connection-context.md

id	title	sidebar_label
sql-connection-context	SQL connection context	SQL connection context

Apache Druid supports two query languages: Druid SQL and native queries. This document describes the SQL language.

Druid SQL supports setting connection parameters on the client, which affect SQL planning. All other context parameters you provide will be attached to Druid queries and can affect how they run. See Query context for details on the possible options.

The connection context can be specified as a "context" object in the JSON API or as a JDBC connection properties object. See examples for each option below.

Example using JSON API

{
  "query" : "SELECT COUNT(*) FROM data_source WHERE foo = 'bar' AND __time > TIMESTAMP '2000-01-01 00:00:00'",
  "context" : {
    "sqlTimeZone" : "America/Los_Angeles"
  }
}

Example using JDBC

String url = "jdbc:avatica:remote:url=http://localhost:8082/druid/v2/sql/avatica/";

// Set any query context parameters you need here.
Properties connectionProperties = new Properties();
connectionProperties.setProperty("sqlTimeZone", "America/Los_Angeles");
connectionProperties.setProperty("useCache", "false");

try (Connection connection = DriverManager.getConnection(url, connectionProperties)) {
  // create and execute statements, process result sets, etc
}

Connection context parameters

Configure Druid SQL query planning using the parameters in the table below.

Note that to specify an unique identifier for SQL query, use sqlQueryId instead of queryId, described in Query context. Setting queryId for a SQL request has no effect, all native queries underlying SQL will use an auto-generated queryId.

Parameter	Description	Default value
sqlQueryId	Unique identifier given to this SQL query. For HTTP client, it will be returned in X-Druid-SQL-Query-Id header.	auto-generated
sqlTimeZone	Sets the time zone for this connection, which will affect how time functions and timestamp literals behave. Should be a time zone name like "America/Los_Angeles" or offset like "-08:00".	druid.sql.planner.sqlTimeZone on the Broker (default: UTC)
sqlStringifyArrays	When set to true, result columns which return array values will be serialized into a JSON string in the response instead of as an array (default: true, except for JDBC connections, where it is always false)
useApproximateCountDistinct	Whether to use an approximate cardinality algorithm for COUNT(DISTINCT foo).	druid.sql.planner.useApproximateCountDistinct on the Broker (default: true)
useGroupingSetForExactDistinct	Whether to use grouping sets to execute queries with multiple exact distinct aggregations.	druid.sql.planner.useGroupingSetForExactDistinct on the Broker (default: false)
useApproximateTopN	Whether to use approximate TopN queries when a SQL query could be expressed as such. If false, exact GroupBy queries will be used instead.	druid.sql.planner.useApproximateTopN on the Broker (default: true)