Catalyst — Tree Manipulation Framework
Catalyst is an execution-agnostic framework to represent and manipulate a dataflow graph, i.e. trees of relational operators and expressions.
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Note
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The Catalyst framework were first introduced in SPARK-1251 Support for optimizing and executing structured queries and became part of Apache Spark on 20/Mar/14 19:12. |
The main abstraction in Catalyst is TreeNode that is then used to build trees of Expressions or QueryPlans.
Spark 2.0 uses the Catalyst tree manipulation framework to build an extensible query plan optimizer with a number of query optimizations.
Catalyst supports both rule-based and cost-based optimization.