The Correlated subquery in a Spark SQL is a query within a query that refer the columns from the parent or outer query table. These kind of subquery contains one or more correlations between its columns and the columns produced by the outer query. Spark SQL supports the regular and correlated subqueries. You can use the subqueries to improve the performance of the Spark SQL queries such as limiting the number of records returned by the subquery. Spark SQL Correlated Subquery Spark SQL supports many types of subqueries. However, it…

A subquery in Spark SQL is a select expression that is enclosed in parentheses as a nested query block in a query statement. The subquery in Apache Spark SQL is similar to subquery in other relational databases that may return zero to one or more values to its upper select statements. In this article, we will check Apache Spark SQL supported subqueries and some examples. Spark SQL Supported Subqueries Spark SQL subqueries are another select statement or expression enclosed in parenthesis as a nested query block. You can use these…