org.apache.spark.sql.execution

Class Limit

Object

org.apache.spark.sql.catalyst.trees.TreeNode<PlanType>

org.apache.spark.sql.catalyst.plans.QueryPlan<SparkPlan>

org.apache.spark.sql.execution.SparkPlan

org.apache.spark.sql.execution.Limit

All Implemented Interfaces:

java.io.Serializable, Logging, org.apache.spark.sql.catalyst.trees.UnaryNode<SparkPlan>, scala.Equals, scala.Product

public class Limit
extends SparkPlan
implements UnaryNode, scala.Product, scala.Serializable

:: DeveloperApi :: Take the first limit elements. Note that the implementation is different depending on whether this is a terminal operator or not. If it is terminal and is invoked using executeCollect, this operator uses something similar to Spark's take method on the Spark driver. If it is not terminal or is invoked using execute, we first take the limit on each partition, and then repartition all the data to a single partition to compute the global limit.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
Limit(int limit, SparkPlan child)

Method Summary

Methods

Modifier and Type	Method and Description
SparkPlan	child()
RDD<org.apache.spark.sql.catalyst.expressions.Row>	execute() Runs this query returning the result as an RDD.
org.apache.spark.sql.catalyst.expressions.Row[]	executeCollect() A custom implementation modeled after the take function on RDDs but which never runs any job locally.
int	limit()
scala.collection.Seq<org.apache.spark.sql.catalyst.expressions.Attribute>	output()
org.apache.spark.sql.catalyst.plans.physical.SinglePartition$	outputPartitioning() Specifies how data is partitioned across different nodes in the cluster.

Methods inherited from class org.apache.spark.sql.execution.SparkPlan

codegenEnabled, makeCopy, requiredChildDistribution

Methods inherited from class org.apache.spark.sql.catalyst.plans.QueryPlan

expressions, inputSet, missingInput, org$apache$spark$sql$catalyst$plans$QueryPlan$$transformExpressionDown$1, org$apache$spark$sql$catalyst$plans$QueryPlan$$transformExpressionUp$1, outputSet, printSchema, references, schema, schemaString, simpleString, statePrefix, transformAllExpressions, transformExpressions, transformExpressionsDown, transformExpressionsUp

Methods inherited from class org.apache.spark.sql.catalyst.trees.TreeNode

apply, argString, asCode, children, collect, fastEquals, flatMap, foreach, generateTreeString, getNodeNumbered, map, mapChildren, nodeName, numberedTreeString, otherCopyArgs, stringArgs, toString, transform, transformChildrenDown, transformChildrenUp, transformDown, transformUp, treeString, withNewChildren

Methods inherited from class Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.apache.spark.sql.catalyst.trees.UnaryNode

children

Methods inherited from interface scala.Product

productArity, productElement, productIterator, productPrefix

Methods inherited from interface scala.Equals

canEqual, equals

Methods inherited from interface org.apache.spark.Logging

initializeIfNecessary, initializeLogging, isTraceEnabled, log_, log, logDebug, logDebug, logError, logError, logInfo, logInfo, logName, logTrace, logTrace, logWarning, logWarning

Constructor Detail

Limit

public Limit(int limit,
     SparkPlan child)

Method Detail

limit

public int limit()

child

public SparkPlan child()

Specified by:

child in interface org.apache.spark.sql.catalyst.trees.UnaryNode<SparkPlan>

output

public scala.collection.Seq<org.apache.spark.sql.catalyst.expressions.Attribute> output()

Specified by:

output in class org.apache.spark.sql.catalyst.plans.QueryPlan<SparkPlan>

outputPartitioning

public org.apache.spark.sql.catalyst.plans.physical.SinglePartition$ outputPartitioning()

Description copied from class: SparkPlan

Specifies how data is partitioned across different nodes in the cluster.

Overrides:

outputPartitioning in class SparkPlan

executeCollect

public org.apache.spark.sql.catalyst.expressions.Row[] executeCollect()

A custom implementation modeled after the take function on RDDs but which never runs any job locally. This is to avoid shipping an entire partition of data in order to retrieve only a few rows.

Overrides:

executeCollect in class SparkPlan

execute

public RDD<org.apache.spark.sql.catalyst.expressions.Row> execute()

Description copied from class: SparkPlan

Runs this query returning the result as an RDD.

Specified by:

execute in class SparkPlan