simpledb

Class Query

java.lang.Object

simpledb.Query

All Implemented Interfaces:

java.io.Serializable

public class Query
extends java.lang.Object
implements java.io.Serializable

Query is a wrapper class to manage the execution of queries. It takes a query plan in the form of a high level DbIterator (built by initiating the constructors of query plans) and runs it as a part of a specified transaction.

Author:

Sam Madden

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
private LogicalPlan	logicalPlan
private DbIterator	op
private static long	serialVersionUID
private boolean	started
(package private) TransactionId	tid

Constructor Summary

Constructors

Constructor and Description
Query(DbIterator root, TransactionId t)
Query(TransactionId t)

Method Summary

Methods

Modifier and Type	Method and Description
void	close() Close the iterator
void	execute()
LogicalPlan	getLogicalPlan()
TupleDesc	getOutputTupleDesc()
DbIterator	getPhysicalPlan()
TransactionId	getTransactionId()
boolean	hasNext()
Tuple	next() Returns the next tuple, or throws NoSuchElementException if the iterator is closed.
void	setLogicalPlan(LogicalPlan lp)
void	setPhysicalPlan(DbIterator pp)
void	start()

Methods inherited from class java.lang.Object

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

Field Detail

serialVersionUID

private static final long serialVersionUID

See Also:

Constant Field Values

op

private transient DbIterator op

logicalPlan

private transient LogicalPlan logicalPlan

tid

TransactionId tid

started

private transient boolean started

Constructor Detail

Query

public Query(TransactionId t)

Query

public Query(DbIterator root,
     TransactionId t)

Method Detail

getTransactionId

public TransactionId getTransactionId()

setLogicalPlan

public void setLogicalPlan(LogicalPlan lp)

getLogicalPlan

public LogicalPlan getLogicalPlan()

setPhysicalPlan

public void setPhysicalPlan(DbIterator pp)

getPhysicalPlan

public DbIterator getPhysicalPlan()

start

public void start()
           throws java.io.IOException,
                  DbException,
                  TransactionAbortedException

Throws:

java.io.IOException

DbException

TransactionAbortedException

getOutputTupleDesc

public TupleDesc getOutputTupleDesc()

hasNext

public boolean hasNext()
                throws DbException,
                       TransactionAbortedException

Returns:

true if there are more tuples remaining.

Throws:

DbException

TransactionAbortedException

next

public Tuple next()
           throws DbException,
                  java.util.NoSuchElementException,
                  TransactionAbortedException

Returns the next tuple, or throws NoSuchElementException if the iterator is closed.

Returns:

The next tuple in the iterator

Throws:

DbException - If there is an error in the database system

java.util.NoSuchElementException - If the iterator has finished iterating

TransactionAbortedException - If the transaction is aborted (e.g., due to a deadlock)

close

public void close()
           throws java.io.IOException

Close the iterator

Throws:

java.io.IOException

execute

public void execute()
             throws java.io.IOException,
                    DbException,
                    TransactionAbortedException

Throws:

java.io.IOException

DbException

TransactionAbortedException