RelDistribution (Apache Calcite API)

All Superinterfaces:

java.lang.Comparable<RelMultipleTrait>, RelMultipleTrait, RelTrait

All Known Implementing Classes:

RelDistributions.RelDistributionImpl
```
public interface RelDistribution
extends RelMultipleTrait
```
Description of the physical distribution of a relational expression.
TBD:
- Can we shorten RelDistribution.Type.HASH_DISTRIBUTED to HASH, etc.
- Do we need RelDistributions.DEFAULT?
- RelDistributionTraitDef.convert(org.apache.calcite.plan.RelOptPlanner, org.apache.calcite.rel.RelNode, org.apache.calcite.rel.RelDistribution, boolean) does not create specific physical operators as it does in Drill. Drill will need to create rules; or we could allow "converters" to be registered with the planner that are not trait-defs.

Nested Class Summary

Nested Classes
Modifier and Type Interface Description

static class RelDistribution.Type
Type of distribution.

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`RelDistribution`	`apply(Mappings.TargetMapping mapping)`
`java.util.List<java.lang.Integer>`	`getKeys()`	Returns the ordinals of the key columns.
`RelDistribution.Type`	`getType()`	Returns the type of distribution.

Methods inherited from interface java.lang.Comparable
compareTo

Methods inherited from interface org.apache.calcite.plan.RelMultipleTrait
isTop

Methods inherited from interface org.apache.calcite.plan.RelTrait
equals, getTraitDef, hashCode, register, satisfies, toString

- Method Detail
  - getType
```
@Nonnull
RelDistribution.Type getType()
```
    Returns the type of distribution.
  - getKeys
```
@Nonnull
java.util.List<java.lang.Integer> getKeys()
```
    Returns the ordinals of the key columns.
    Order is important for some types (RANGE); other types (HASH) consider it unimportant but impose an arbitrary order; other types (BROADCAST, SINGLETON) never have keys.
  - apply
```
RelDistribution apply(Mappings.TargetMapping mapping)
```