io.druid.sql.calcite.expression

Class Expressions

java.lang.Object

io.druid.sql.calcite.expression.Expressions

public class Expressions
extends Object

A collection of functions for translating from Calcite expressions into Druid objects.

Method Summary

Modifier and Type	Method and Description
static org.apache.calcite.rex.RexNode	fromFieldAccess(RowSignature rowSignature, org.apache.calcite.rel.core.Project project, int fieldNumber) Translate a field access, possibly through a projection, to an underlying Druid dataSource.
static DimFilter	toFilter(PlannerContext plannerContext, RowSignature rowSignature, org.apache.calcite.rex.RexNode expression) Translates "condition" to a Druid filter, or returns null if we cannot translate the condition.
static String	toMathExpression(List<String> rowOrder, org.apache.calcite.rex.RexNode expression) Translate a row-expression to a Druid math expression.
static long	toMillisLiteral(org.apache.calcite.rex.RexNode literal, org.joda.time.DateTimeZone timeZone) Translates "literal" (a TIMESTAMP or DATE literal) to milliseconds since the epoch using the provided session time zone.
static PostAggregator	toPostAggregator(String name, List<String> rowOrder, List<PostAggregatorFactory> finalizingPostAggregatorFactories, org.apache.calcite.rex.RexNode expression) Translate a Calcite row-expression to a Druid PostAggregator.
static RowExtraction	toRowExtraction(PlannerContext plannerContext, List<String> rowOrder, org.apache.calcite.rex.RexNode expression) Translate a Calcite row-expression to a Druid row extraction.

Methods inherited from class java.lang.Object

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

Method Detail

fromFieldAccess

public static org.apache.calcite.rex.RexNode fromFieldAccess(RowSignature rowSignature,
                                                             org.apache.calcite.rel.core.Project project,
                                                             int fieldNumber)

Translate a field access, possibly through a projection, to an underlying Druid dataSource.

Parameters:

rowSignature - row signature of underlying Druid dataSource

project - projection, or null

fieldNumber - number of the field to access

Returns:

row expression

toRowExtraction

public static RowExtraction toRowExtraction(PlannerContext plannerContext,
                                            List<String> rowOrder,
                                            org.apache.calcite.rex.RexNode expression)

Translate a Calcite row-expression to a Druid row extraction. Note that this signature will probably need to change once we support extractions from multiple columns.

Parameters:

plannerContext - SQL planner context

rowOrder - order of fields in the Druid rows to be extracted from

expression - expression meant to be applied on top of the rows

Returns:

RowExtraction or null if not possible

toPostAggregator

public static PostAggregator toPostAggregator(String name,
                                              List<String> rowOrder,
                                              List<PostAggregatorFactory> finalizingPostAggregatorFactories,
                                              org.apache.calcite.rex.RexNode expression)

Translate a Calcite row-expression to a Druid PostAggregator. One day, when possible, this could be folded into toRowExtraction(PlannerContext, List, RexNode).

Parameters:

name - name of the PostAggregator

rowOrder - order of fields in the Druid rows to be extracted from

finalizingPostAggregatorFactories - post-aggregators that should be used for specific entries in rowOrder. May be empty, and individual values may be null. Missing or null values will lead to creation of FieldAccessPostAggregator.

expression - expression meant to be applied on top of the rows

Returns:

PostAggregator or null if not possible

toMathExpression

public static String toMathExpression(List<String> rowOrder,
                                      org.apache.calcite.rex.RexNode expression)

Translate a row-expression to a Druid math expression. One day, when possible, this could be folded into toRowExtraction(PlannerContext, List, RexNode).

Parameters:

rowOrder - order of fields in the Druid rows to be extracted from

expression - expression meant to be applied on top of the rows

Returns:

expression referring to fields in rowOrder, or null if not possible

toMillisLiteral

public static long toMillisLiteral(org.apache.calcite.rex.RexNode literal,
                                   org.joda.time.DateTimeZone timeZone)

Translates "literal" (a TIMESTAMP or DATE literal) to milliseconds since the epoch using the provided session time zone.

Parameters:

literal - TIMESTAMP or DATE literal

timeZone - session time zone

Returns:

milliseconds time

toFilter

public static DimFilter toFilter(PlannerContext plannerContext,
                                 RowSignature rowSignature,
                                 org.apache.calcite.rex.RexNode expression)

Translates "condition" to a Druid filter, or returns null if we cannot translate the condition.

Parameters:

plannerContext - planner context

rowSignature - row signature of the dataSource to be filtered

expression - Calcite row expression