Package org.apache.calcite.rel.metadata

Class RelMdCollation

java.lang.Object

org.apache.calcite.rel.metadata.RelMdCollation

All Implemented Interfaces:

MetadataHandler<BuiltInMetadata.Collation>

public class RelMdCollation
extends java.lang.Object
implements MetadataHandler<BuiltInMetadata.Collation>

RelMdCollation supplies a default implementation of RelMetadataQuery.collations(org.apache.calcite.rel.RelNode) for the standard logical algebra.

Field Summary

Fields

Modifier and Type	Field	Description
static RelMetadataProvider	SOURCE

Constructor Summary

Constructors

Modifier	Constructor	Description
private	RelMdCollation()

Method Summary

Modifier and Type	Method	Description
static java.util.List<RelCollation>	calc(RelMetadataQuery mq, RelNode input, RexProgram program)	Helper method to determine a Calc's collation.
com.google.common.collect.ImmutableList<RelCollation>	collations(EnumerableMergeJoin join, RelMetadataQuery mq)
com.google.common.collect.ImmutableList<RelCollation>	collations(HepRelVertex rel, RelMetadataQuery mq)
com.google.common.collect.ImmutableList<RelCollation>	collations(RelSubset rel, RelMetadataQuery mq)
com.google.common.collect.ImmutableList<RelCollation>	collations(Calc calc, RelMetadataQuery mq)
com.google.common.collect.ImmutableList<RelCollation>	collations(Filter rel, RelMetadataQuery mq)
com.google.common.collect.ImmutableList<RelCollation>	collations(Project project, RelMetadataQuery mq)
com.google.common.collect.ImmutableList<RelCollation>	collations(SortExchange sort, RelMetadataQuery mq)
com.google.common.collect.ImmutableList<RelCollation>	collations(Sort sort, RelMetadataQuery mq)
com.google.common.collect.ImmutableList<RelCollation>	collations(TableScan scan, RelMetadataQuery mq)
com.google.common.collect.ImmutableList<RelCollation>	collations(Values values, RelMetadataQuery mq)
com.google.common.collect.ImmutableList<RelCollation>	collations(Window rel, RelMetadataQuery mq)
com.google.common.collect.ImmutableList<RelCollation>	collations(RelNode rel, RelMetadataQuery mq)	Catch-all implementation for BuiltInMetadata.Collation.collations(), invoked using reflection, for any relational expression not handled by a more specific method.
private static com.google.common.collect.Ordering<java.util.List<RexLiteral>>	comparator(RelFieldCollation fieldCollation)
static java.util.List<RelCollation>	filter(RelMetadataQuery mq, RelNode input)	Helper method to determine a Filter's collation.
MetadataDef<BuiltInMetadata.Collation>	getDef()
static java.util.List<RelCollation>	limit(RelMetadataQuery mq, RelNode input)	Helper method to determine a limit's collation.
static java.util.List<RelCollation>	mergeJoin(RelMetadataQuery mq, RelNode left, RelNode right, ImmutableIntList leftKeys, ImmutableIntList rightKeys)	Helper method to determine a Join's collation assuming that it uses a merge-join algorithm.
static java.util.List<RelCollation>	project(RelMetadataQuery mq, RelNode input, java.util.List<? extends RexNode> projects)	Helper method to determine a Project's collation.
static java.util.List<RelCollation>	sort(RelCollation collation)	Helper method to determine a Sort's collation.
static java.util.List<RelCollation>	table(RelOptTable table)	Helper method to determine a TableScan's collation.
static java.util.List<RelCollation>	values(RelMetadataQuery mq, RelDataType rowType, com.google.common.collect.ImmutableList<com.google.common.collect.ImmutableList<RexLiteral>> tuples)	Helper method to determine a Values's collation.
static java.util.List<RelCollation>	window(RelMetadataQuery mq, RelNode input, com.google.common.collect.ImmutableList<Window.Group> groups)	Helper method to determine a Window's collation.

Methods inherited from class java.lang.Object

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

Field Detail

SOURCE

public static final RelMetadataProvider SOURCE

Constructor Detail

RelMdCollation

private RelMdCollation()

Method Detail

getDef

public MetadataDef<BuiltInMetadata.Collation> getDef()

Specified by:

getDef in interface MetadataHandler<BuiltInMetadata.Collation>

collations

public com.google.common.collect.ImmutableList<RelCollation> collations(RelNode rel,
                                                                        RelMetadataQuery mq)

Catch-all implementation for BuiltInMetadata.Collation.collations(), invoked using reflection, for any relational expression not handled by a more specific method.

Union, Intersect, Minus, Join, SemiJoin, Correlate do not in general return sorted results (but implementations using particular algorithms may).

Parameters:

rel - Relational expression

Returns:

Relational expression's collations

See Also:

RelMetadataQuery.collations(RelNode)

collations

public com.google.common.collect.ImmutableList<RelCollation> collations(Window rel,
                                                                        RelMetadataQuery mq)

collations

public com.google.common.collect.ImmutableList<RelCollation> collations(Filter rel,
                                                                        RelMetadataQuery mq)

collations

public com.google.common.collect.ImmutableList<RelCollation> collations(TableScan scan,
                                                                        RelMetadataQuery mq)

collations

public com.google.common.collect.ImmutableList<RelCollation> collations(EnumerableMergeJoin join,
                                                                        RelMetadataQuery mq)

collations

public com.google.common.collect.ImmutableList<RelCollation> collations(Sort sort,
                                                                        RelMetadataQuery mq)

collations

public com.google.common.collect.ImmutableList<RelCollation> collations(SortExchange sort,
                                                                        RelMetadataQuery mq)

collations

public com.google.common.collect.ImmutableList<RelCollation> collations(Project project,
                                                                        RelMetadataQuery mq)

collations

public com.google.common.collect.ImmutableList<RelCollation> collations(Calc calc,
                                                                        RelMetadataQuery mq)

collations

public com.google.common.collect.ImmutableList<RelCollation> collations(Values values,
                                                                        RelMetadataQuery mq)

collations

public com.google.common.collect.ImmutableList<RelCollation> collations(HepRelVertex rel,
                                                                        RelMetadataQuery mq)

collations

public com.google.common.collect.ImmutableList<RelCollation> collations(RelSubset rel,
                                                                        RelMetadataQuery mq)

table

public static java.util.List<RelCollation> table(RelOptTable table)

Helper method to determine a TableScan's collation.

sort

public static java.util.List<RelCollation> sort(RelCollation collation)

Helper method to determine a Sort's collation.

filter

public static java.util.List<RelCollation> filter(RelMetadataQuery mq,
                                                  RelNode input)

Helper method to determine a Filter's collation.

limit

public static java.util.List<RelCollation> limit(RelMetadataQuery mq,
                                                 RelNode input)

Helper method to determine a limit's collation.

calc

public static java.util.List<RelCollation> calc(RelMetadataQuery mq,
                                                RelNode input,
                                                RexProgram program)

Helper method to determine a Calc's collation.

project

public static java.util.List<RelCollation> project(RelMetadataQuery mq,
                                                   RelNode input,
                                                   java.util.List<? extends RexNode> projects)

Helper method to determine a Project's collation.

window

public static java.util.List<RelCollation> window(RelMetadataQuery mq,
                                                  RelNode input,
                                                  com.google.common.collect.ImmutableList<Window.Group> groups)

Helper method to determine a Window's collation.

A Window projects the fields of its input first, followed by the output from each of its windows. Assuming (quite reasonably) that the implementation does not re-order its input rows, then any collations of its input are preserved.

values

public static java.util.List<RelCollation> values(RelMetadataQuery mq,
                                                  RelDataType rowType,
                                                  com.google.common.collect.ImmutableList<com.google.common.collect.ImmutableList<RexLiteral>> tuples)

Helper method to determine a Values's collation.

We actually under-report the collations. A Values with 0 or 1 rows - an edge case, but legitimate and very common - is ordered by every permutation of every subset of the columns.

So, our algorithm aims to:

• produce at most N collations (where N is the number of columns);
• make each collation as long as possible;
• do not repeat combinations already emitted - if we've emitted (a, b) do not later emit (b, a);
• probe the actual values and make sure that each collation is consistent with the data

So, for an empty Values with 4 columns, we would emit (a, b, c, d), (b, c, d), (c, d), (d).

comparator

private static com.google.common.collect.Ordering<java.util.List<RexLiteral>> comparator(RelFieldCollation fieldCollation)

mergeJoin

public static java.util.List<RelCollation> mergeJoin(RelMetadataQuery mq,
                                                     RelNode left,
                                                     RelNode right,
                                                     ImmutableIntList leftKeys,
                                                     ImmutableIntList rightKeys)

Helper method to determine a Join's collation assuming that it uses a merge-join algorithm.

If the inputs are sorted on other keys in addition to the join key, the result preserves those collations too.