Rule¶

Rule is an abstraction of named transformations of TreeNodes.

Rule can be executed on a TreeNode to produce a new TreeNode.

Rule is primarily used to create a batch of rules for a RuleExecutor.

TreeType¶

Rule is a Scala abstract class constructor (generic class) with TreeType type that is a subtype of TreeNode (e.g. LogicalPlan, SparkPlan, Expression).

abstract class Rule[TreeType <: TreeNode[_]]

Contract¶

Executing Rule¶

apply(
  plan: TreeType): TreeType

Applies the rule to a TreeType

Used when:

• QueryExecution utility is used to prepareForExecution
• AdaptiveSparkPlanExec utility is used to applyPhysicalRules

Name¶

ruleName: String

ruleName is the name of a rule that is a class name with no ending $ (that Scala generates for objects).

Notable Use Cases¶

The other notable use cases of Rule are as follows:

• SparkSessionExtensions

• When ExperimentalMethods is requested for extraOptimizations

• When BaseSessionStateBuilder is requested for customResolutionRules, customPostHocResolutionRules, customOperatorOptimizationRules, and the Optimizer

• When Analyzer is requested for extendedResolutionRules and postHocResolutionRules (see BaseSessionStateBuilder and HiveSessionStateBuilder)

• When Optimizer is requested for extendedOperatorOptimizationRules

• When QueryExecution is requested for preparations