org.apache.pig.newplan.logical.relational

Class LogicalPlan

java.lang.Object

org.apache.pig.newplan.BaseOperatorPlan

org.apache.pig.newplan.logical.relational.LogicalPlan

All Implemented Interfaces:

Serializable, OperatorPlan

public class LogicalPlan
extends BaseOperatorPlan

LogicalPlan is the logical view of relational operations Pig will execute for a given script. Note that it contains only relational operations. All expressions will be contained in LogicalExpressionPlans inside each relational operator.

See Also:

Serialized Form

Field Summary

Fields inherited from class org.apache.pig.newplan.BaseOperatorPlan

fromEdges, log, ops, softFromEdges, softToEdges, toEdges

Constructor Summary

Constructors

Constructor and Description
LogicalPlan()
LogicalPlan(LogicalPlan other)

Method Summary

Methods

Modifier and Type	Method and Description
void	explain(PrintStream ps, String format, boolean verbose)
Operator	findByAlias(String alias)
String	getHash()
String	getSignature() Returns the signature of the LogicalPlan.
boolean	isEqual(OperatorPlan other) Equality is checked by calling equals on every leaf in the plan.

Methods inherited from class org.apache.pig.newplan.BaseOperatorPlan

add, connect, connect, createSoftLink, disconnect, getOperators, getPredecessors, getSinks, getSoftLinkPredecessors, getSoftLinkSuccessors, getSources, getSuccessors, insertBetween, isConnected, isEqual, pathExists, remove, removeAndReconnect, removeSoftLink, replace, size, toString

Methods inherited from class java.lang.Object

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

Constructor Detail

LogicalPlan

public LogicalPlan(LogicalPlan other)

LogicalPlan

public LogicalPlan()

Method Detail

isEqual

public boolean isEqual(OperatorPlan other)
                throws FrontendException

Equality is checked by calling equals on every leaf in the plan. This assumes that plans are always connected graphs. It is somewhat inefficient since every leaf will test equality all the way to every root. But it is only intended for use in testing, so that should be ok. Checking predecessors (as opposed to successors) was chosen because splits (which have multiple successors) do not depend on order of outputs for correctness, whereas joins (with multiple predecessors) do. That is, reversing the outputs of split in the graph has no correctness implications, whereas reversing the inputs of join can. This method of doing equals will detect predecessors in different orders but not successors in different orders. It will return false if either plan has non deterministic EvalFunc.

Specified by:

isEqual in interface OperatorPlan

Overrides:

isEqual in class BaseOperatorPlan

Parameters:

other - object to compare

Returns:

boolean if both the plans are equivalent

Throws:

FrontendException

explain

public void explain(PrintStream ps,
           String format,
           boolean verbose)
             throws FrontendException

Overrides:

explain in class BaseOperatorPlan

Throws:

FrontendException

findByAlias

public Operator findByAlias(String alias)

getSignature

public String getSignature()
                    throws FrontendException

Returns the signature of the LogicalPlan. The signature is a unique identifier for a given plan generated by a Pig script. The same script run multiple times with the same version of Pig is guaranteed to produce the same signature, even if the input or output locations differ.

Returns:

a unique identifier for the logical plan

Throws:

FrontendException - if signature can't be computed

getHash

public String getHash()
               throws FrontendException

Throws:

FrontendException