ca.uqac.dim.turtledb

Class Engine

java.lang.Object

ca.uqac.dim.turtledb.Engine

public class Engine
extends java.lang.Object

An engine does two things:

1. It locally hosts relations (or fragments thereof)
2. It receives relational query trees and evaluates them against the locally-hosted relations, then outputs the resulting relation

Author:

sylvain

Field Summary

Fields

Modifier and Type	Field and Description
protected int	m_numTuplesReceived The total number of tuples received by this site
protected java.util.List<Relation>	m_pendingQueries The list of query plans that await computation
protected java.lang.String	m_siteName The site's name
protected java.util.Map<java.lang.String,Relation>	m_tables

Constructor Summary

Constructors

Constructor and Description
Engine(java.lang.String name) Instantiates a new database query engine.

Method Summary

Modifier and Type	Method and Description
void	addQuery(java.util.Collection<Relation> queries) Add a set of queries.
void	addQuery(Relation query) Add a query to process.
Table	evaluate(org.w3c.dom.Document d)
Table	evaluate(Relation query) Locally evaluates a query
Table	evaluate(java.lang.String s) Locally evaluates a query
QueryPlan	getQueryPlan(Relation query) Creates a query plan from a given query
int	getStorageSize() Returns the total number of tuples hosted locally by this database engine.
int	getTuplesReceived() Returns the number of tuples this engine received from the outside world.
java.util.Set<Relation>	processPendingQueries() Process any pending queries
void	putRelation(java.lang.String name, Relation r) Stores a new relation within the engine.

Methods inherited from class java.lang.Object

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

Field Detail

m_tables

protected java.util.Map<java.lang.String,Relation> m_tables

m_pendingQueries

protected java.util.List<Relation> m_pendingQueries

The list of query plans that await computation

m_numTuplesReceived

protected int m_numTuplesReceived

The total number of tuples received by this site

m_siteName

protected java.lang.String m_siteName

The site's name

Constructor Detail

Engine

public Engine(java.lang.String name)

Instantiates a new database query engine.

Method Detail

putRelation

public void putRelation(java.lang.String name,
                        Relation r)

Stores a new relation within the engine. Normally one would only store instances of Table here (although any relation can be passed).

Parameters:

name - The relation's name

r - The relation

addQuery

public void addQuery(Relation query)

Add a query to process.

Parameters:

query - The query

addQuery

public void addQuery(java.util.Collection<Relation> queries)

Add a set of queries. This is just the repeated application of addQuery to every element of the collection.

Parameters:

queries - The collection of queries to add

processPendingQueries

public java.util.Set<Relation> processPendingQueries()

Process any pending queries

Returns:

The results of queries that have been processed

getQueryPlan

public QueryPlan getQueryPlan(Relation query)

Creates a query plan from a given query

Parameters:

query - The query to execute

Returns:

The query plan

evaluate

public Table evaluate(Relation query)

Locally evaluates a query

Parameters:

query - The query XML document

Returns:

A new table containing the results of that query

evaluate

public Table evaluate(java.lang.String s)

Locally evaluates a query

Parameters:

s - The query string

Returns:

A new table containing the results of that query

evaluate

public Table evaluate(org.w3c.dom.Document d)

getStorageSize

public int getStorageSize()

Returns the total number of tuples hosted locally by this database engine. This can be used, in conjunction with getTuplesReceived, to compute cost metrics.

Returns:

The number of tuples

getTuplesReceived

public int getTuplesReceived()

Returns the number of tuples this engine received from the outside world. This can be used, in conjunction with getStorageSize, to compute cost metrics.

Returns:

The number of tuples