ConstantFolding Logical Optimization¶

ConstantFolding is a base logical optimization that <>.

ConstantFolding is part of the Operator Optimization before Inferring Filters fixed-point batch in the standard batches of the Logical Optimizer.

ConstantFolding is simply a <> for transforming <>, i.e. Rule[LogicalPlan].

[source, scala]¶

scala> spark.range(1).select(lit(3) > 2).explain(true) ... TRACE SparkOptimizer: === Applying Rule org.apache.spark.sql.catalyst.optimizer.ConstantFolding === !Project [(3 > 2) AS (3 > 2)#3] Project [true AS (3 > 2)#3] +- Range (0, 1, step=1, splits=Some(8)) +- Range (0, 1, step=1, splits=Some(8))

scala> spark.range(1).select('id + 'id > 0).explain(true) ... TRACE SparkOptimizer: === Applying Rule org.apache.spark.sql.catalyst.optimizer.ConstantFolding === !Project [((id#7L + id#7L) > cast(0 as bigint)) AS ((id + id) > 0)#10] Project [((id#7L + id#7L) > 0) AS ((id + id) > 0)#10] +- Range (0, 1, step=1, splits=Some(8)) +- Range (0, 1, step=1, splits=Some(8))

Executing Rule¶

apply(plan: LogicalPlan): LogicalPlan

apply...FIXME

apply is part of the Rule abstraction.