![]() If you view the native explanation of a SQL UNNEST, you'll notice that Druid uses j0.unnest as a virtual column to perform the unnest.Specifically, it is not needed when you're unnesting an inline array since the array itself is the datasource. This is needed in most cases of the UNNEST function. Notice the comma between the datasource and the UNNEST function.You can unnest multiple source expressions in a single query.You must include the context parameter "enableUnnest": true.Keep the following things in mind when writing your query: If you don't provide this, Druid uses a nondescriptive name, such as EXPR$0. Replace table_alias_name and column_alias_name with a table and column name you want to alias the unnested results to. Use it to specify the output, which can be an existing column or a new one. The AS table_alias_name(column_alias_name) clause is not required but is highly recommended.ARRAY_CONCAT(dim1,dim2) if you want to concatenate two multi-value dimensions.ARRAY if you want to make an array out of two dimensions.For example, you can call UNNEST on the following: You can also specify any expression that has an SQL array datatype. If the dimension you are unnesting is a multi-value dimension, you have to specify MV_TO_ARRAY(dimension) to convert it to an implicit ARRAY type. The source_expression for the UNNEST function must be an array and can come from any expression.For example, FROM (SELECT columnA,columnB,columnC from a_table). A subset of a table based on a query, a filter, or a JOIN.The datasource for UNNEST can be any Druid datasource, such as the following:.The following is the general syntax for UNNEST, specifically a query that returns the column that gets unnested: SELECT column_alias_name FROM datasource, UNNEST(source_expression1) AS table_alias_name1(column_alias_name1), UNNEST(source_expression2) AS table_alias_name2(column_alias_name2). The source for UNNEST can be an array or an input that's been transformed into an array, such as with helper functions like MV_TO_ARRAY or ARRAY. It's the SQL equivalent to the unnest datasource. It is not recommended to use this feature in production at this time. They exist only in the SQL layer.įor more information about table, lookup, query, and join datasources, refer to the Datasources Unlike the other options for theįROM clause, metadata tables are not considered datasources. Metadata tables from the INFORMATION_SCHEMA or sys schemas.The join condition must be an equality between expressions from the left- and right-hand side Joins between anything in this list, except between native datasources (table, lookup,.Note that lookups canĪlso be queried using the LOOKUP function. Lookups from the lookup schema, for example untries.This is the default schema, so Druid tableĭatasources can be referenced as either druid.dataSourceName or simply dataSourceName. Table datasources from the druid schema.The FROM clause can refer to any of the following: SQL query context for information about the query context parameters that affect SQL planning.ĭruid SQL supports SELECT queries with the following structure:.SQL JDBC driver API for information about the JDBC driver API.Druid SQL API for information on the HTTP API.Query translation for information about how Druid translates SQL queries to native queries before running them.SQL multi-value string functions for operations you can perform on string dimensions containing multiple values.Scalar functions for Druid SQL scalar functions including numeric and string functions, IP address functions, Sketch functions, and more.Aggregation functions for a list of aggregation functions available for Druid SQL SELECT statements.Data types for a list of supported data types for Druid columns. ![]() Set Broker runtime properties to configure the query plan and JDBC querying.įor information on permissions needed to make SQL queries, see Defining SQL permissions.įor more information and SQL querying options see: To learn about translation and how to get the best performance from Druid SQL, see SQL query translation. Druid translates SQL queries into its native query language. You can query data in Druid datasources using Druid SQL. This document describes the SQL language. Moment Sketches for Approximate Quantiles moduleĪpache Druid supports two query languages: Druid SQL and native queries.Key/Value Stores (HBase/Cassandra/OpenTSDB) ![]()
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