org.apache.pig.experimental.logical.relational
Class LogicalSchema

java.lang.Object
  org.apache.pig.experimental.logical.relational.LogicalSchema

public class LogicalSchema
extends Object

Schema, from a logical perspective.

Nested Class Summary

static class

LogicalSchema.LogicalFieldSchema

Constructor Summary

LogicalSchema()

Method Summary

void	addField(LogicalSchema.LogicalFieldSchema field) Add a field to this schema.
int	findField(long uid) Look for the index of the field that contains the specified uid
LogicalSchema.LogicalFieldSchema	getField(int fieldNum) Fetch a field by field number
LogicalSchema.LogicalFieldSchema	getField(String alias) Fetch a field by alias
List<LogicalSchema.LogicalFieldSchema>	getFields() Get all fields
boolean	isEqual(Object other) Two schemas are equal if they are of equal size and their fields schemas considered in order are equal.
static LogicalSchema	merge(LogicalSchema s1, LogicalSchema s2) Merge two schemas.
int	size() Get the size of the schema.
String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

LogicalSchema

public LogicalSchema()

Method Detail

addField

public void addField(LogicalSchema.LogicalFieldSchema field)

Add a field to this schema.

Parameters:

field - to be added to the schema

getField

public LogicalSchema.LogicalFieldSchema getField(String alias)

Fetch a field by alias

Parameters:

alias -

Returns:

field associated with alias, or null if no such field

getField

public LogicalSchema.LogicalFieldSchema getField(int fieldNum)

Fetch a field by field number

Parameters:

fieldNum - field number to fetch

Returns:

field

getFields

public List<LogicalSchema.LogicalFieldSchema> getFields()

Get all fields

Returns:

list of all fields

size

public int size()

Get the size of the schema.

Returns:

size

isEqual

public boolean isEqual(Object other)

Two schemas are equal if they are of equal size and their fields schemas considered in order are equal.

findField

public int findField(long uid)

Look for the index of the field that contains the specified uid

Parameters:

uid - the uid to look for

Returns:

the index of the field, -1 if not found

merge

public static LogicalSchema merge(LogicalSchema s1,
                                  LogicalSchema s2)

Merge two schemas.

Parameters:

s1 -

s2 -

Returns:

a merged schema, or null if the merge fails

toString

public String toString()

Overrides:

toString in class Object