org.apache.gravitino.rel.expressions.distributions

Class Distributions

java.lang.Object

org.apache.gravitino.rel.expressions.distributions.Distributions

public class Distributions
extends java.lang.Object

Helper methods to create distributions to pass into Apache Gravitino.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	Distributions.DistributionImpl Create a distribution on columns.

Field Summary

Fields

Modifier and Type	Field and Description
static Distribution	HASH List bucketing strategy hash, TODO: #1505 Separate the bucket number from the Distribution.
static Distribution	NONE NONE is used to indicate that there is no distribution.
static Distribution	RANGE List bucketing strategy range, TODO: #1505 Separate the bucket number from the Distribution.

Method Summary

Modifier and Type	Method and Description
static Distribution	even(int number, Expression... expressions) Create a distribution by evenly distributing the data across the number of buckets.
static Distribution	fields(Strategy strategy, int number, java.lang.String[]... fieldNames) Create a distribution on columns.
static Distribution	hash(int number, Expression... expressions) Create a distribution by hashing the data across the number of buckets.
static Distribution	of(Strategy strategy, int number, Expression... expressions) Create a distribution by the given strategy.

Methods inherited from class java.lang.Object

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

Field Detail

NONE

public static final Distribution NONE

NONE is used to indicate that there is no distribution.

HASH

public static final Distribution HASH

List bucketing strategy hash, TODO: #1505 Separate the bucket number from the Distribution.

RANGE

public static final Distribution RANGE

List bucketing strategy range, TODO: #1505 Separate the bucket number from the Distribution.

Method Detail

even

public static Distribution even(int number,
                                Expression... expressions)

Create a distribution by evenly distributing the data across the number of buckets.

Parameters:

number - The number of buckets

expressions - The expressions to distribute by

Returns:

The created even distribution

hash

public static Distribution hash(int number,
                                Expression... expressions)

Create a distribution by hashing the data across the number of buckets.

Parameters:

number - The number of buckets

expressions - The expressions to distribute by

Returns:

The created hash distribution

of

public static Distribution of(Strategy strategy,
                              int number,
                              Expression... expressions)

Create a distribution by the given strategy.

Parameters:

strategy - The strategy to use

number - The number of buckets

expressions - The expressions to distribute by

Returns:

The created distribution

fields

public static Distribution fields(Strategy strategy,
                                  int number,
                                  java.lang.String[]... fieldNames)

Create a distribution on columns. Like distribute by (a) or (a, b), for complex like distributing by (func(a), b) or (func(a), func(b)), please use Distributions.DistributionImpl.Builder to create.

   NOTE: a, b, c are column names.

   SQL syntax: distribute by hash(a, b) buckets 5
   fields(Strategy.HASH, 5, new String[]{"a"}, new String[]{"b"});

   SQL syntax: distribute by hash(a, b, c) buckets 10
   fields(Strategy.HASH, 10, new String[]{"a"}, new String[]{"b"}, new String[]{"c"});

   SQL syntax: distribute by EVEN(a) buckets 128
   fields(Strategy.EVEN, 128, new String[]{"a"});
 

Parameters:

strategy - The strategy to use.

number - The number of buckets.

fieldNames - The field names to distribute by.

Returns:

The created distribution.