org.apache.druid.segment.virtual

Class ExpressionPlanner

java.lang.Object

org.apache.druid.segment.virtual.ExpressionPlanner

public class ExpressionPlanner
extends Object

Method Summary

Modifier and Type	Method and Description
static ExpressionPlan	plan(ColumnInspector inspector, Expr expression) Druid tries to be chill to expressions to make up for not having a well defined table schema across segments.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

plan

public static ExpressionPlan plan(ColumnInspector inspector,
                                  Expr expression)

Druid tries to be chill to expressions to make up for not having a well defined table schema across segments. This method performs some analysis to determine what sort of selectors can be constructed on top of an expression, whether or not the expression will need implicitly mapped across multi-valued inputs, if the expression produces multi-valued outputs, is vectorizable, and everything else interesting when making a selector. Results are stored in a ExpressionPlan, which can be examined to do whatever is necessary to make things function properly.