Package nl.cwi.monetdb.embedded.env

Class MonetDBEmbeddedConnection

java.lang.Object

nl.cwi.monetdb.embedded.env.MonetDBEmbeddedConnection

All Implemented Interfaces:

Closeable, AutoCloseable

Direct Known Subclasses:

JDBCEmbeddedConnection

public class MonetDBEmbeddedConnection
extends Object
implements Closeable

A single connection to a MonetDB database instance. Communication between Java and native C is done via JNI.
Note: You can have only one Embedded MonetDB database running per JVM process.

Author:

Pedro Ferreira

Field Summary

Fields

Modifier and Type	Field	Description
protected long	connectionPointer	The C connection pointer.

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	MonetDBEmbeddedConnection(long connectionPointer)

Method Summary

Modifier and Type	Method	Description
boolean	checkIfTableExists(String schemaName, String tableName)	Check if a table exists in the database.
void	close()	Shuts down this connection.
protected void	closeConnectionImplementation()	When the database shuts down, this method is called instead
void	commit()	Commits the current transaction.
QueryResultSet	executeQuery(String query)	Executes a SQL query with a result set.
int	executeUpdate(String query)	Executes a SQL query without a result set, returning the number of rows it affected.
protected void	finalize()	Overriding the finalize method to close the connection
boolean	getAutoCommit()	Retrieves the current auto-commit mode for this connection.
MonetDBTable	getMonetDBTable(String tableName)	Retrieves a MonetDB Table in the current schema for further operations.
MonetDBTable	getMonetDBTable(String schemaName, String tableName)	Retrieves a database table for further operations on it such as appending data.
long	getRandomIdentifier()	Retrieves a long number randomly generated, used to identify the connection uniquely.
String	getSchema()	Retrieves the current schema set on the connection.
boolean	isClosed()	Tells if the connection has been closed or not.
QueryResultSet	listTables(boolean listSystemTables)	Performs a listing of the existing tables with schemas.
MonetDBEmbeddedPreparedStatement	prepareStatement(String query)	Starts a prepared statement.
void	releaseSavepoint(Savepoint savepoint)	Removes the given Savepoint object from the current transaction.
void	removeTable(String schemaName, String tableName)	Deletes a table if exists in the database.
void	rollback()	Rollbacks the current transaction.
void	rollback(Savepoint savepoint)	Undoes all changes made after the given Savepoint object was set.
void	setAutoCommit(boolean autoCommit)	Sets this connection's auto-commit mode to the given state.
Savepoint	setSavepoint()	Creates an unnamed savepoint in the current transaction and returns the new Savepoint object that represents it.
Savepoint	setSavepoint(String name)	Creates a savepoint with the given name in the current transaction and returns the new Savepoint object that represents it.
void	setSchema(String newSchema)	Sets the current schema for this connection.
void	startTransaction()	Begins a transaction.
String	toString()	A brief description of the connection.

Methods inherited from class java.lang.Object

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

Field Detail

connectionPointer

protected volatile long connectionPointer

The C connection pointer.

Constructor Detail

MonetDBEmbeddedConnection

protected MonetDBEmbeddedConnection(long connectionPointer)

Method Detail

getRandomIdentifier

public long getRandomIdentifier()

Retrieves a long number randomly generated, used to identify the connection uniquely.

Returns:

The random identifier

isClosed

public boolean isClosed()

Tells if the connection has been closed or not.

Returns:

A boolean indicating if the connection has been cleaned or not

getSchema

public String getSchema()
                 throws MonetDBEmbeddedException

Retrieves the current schema set on the connection.

Returns:

A Java String with the name of the schema

Throws:

MonetDBEmbeddedException - If an error in the database occurred

setSchema

public void setSchema(String newSchema)
               throws MonetDBEmbeddedException

Sets the current schema for this connection.

Parameters:

newSchema - Java String with the name of the schema

Throws:

MonetDBEmbeddedException - If an error in the database occurred

getAutoCommit

public boolean getAutoCommit()
                      throws MonetDBEmbeddedException

Retrieves the current auto-commit mode for this connection.

Returns:

the current state of this Connection object's auto-commit mode

Throws:

MonetDBEmbeddedException - if a database access error occurs

setAutoCommit

public void setAutoCommit(boolean autoCommit)
                   throws MonetDBEmbeddedException

Sets this connection's auto-commit mode to the given state. If a connection is in auto-commit mode, then all its SQL statements will be executed and committed as individual transactions. Otherwise, its SQL statements are grouped into transactions that are terminated by a call to either the method commit or the method rollback. By default, new connections are in auto-commit mode. NOTE: If this method is called during a transaction, the transaction is committed.

Parameters:

autoCommit - true to enable auto-commit mode; false to disable it

Throws:

MonetDBEmbeddedException - if a database access error occurs

startTransaction

public void startTransaction()
                      throws MonetDBEmbeddedException

Begins a transaction. WARNING Starting a transaction will turn the autocommit mode off!

Throws:

MonetDBEmbeddedException - If an error in the database occurred

commit

public void commit()
            throws MonetDBEmbeddedException

Commits the current transaction. After committing a transaction the autocommit mode is turned back on.

Throws:

MonetDBEmbeddedException - If an error in the database occurred

rollback

public void rollback()
              throws MonetDBEmbeddedException

Rollbacks the current transaction. After rollback a transaction the autocommit mode is turned back on.

Throws:

MonetDBEmbeddedException - If an error in the database occurred

setSavepoint

public Savepoint setSavepoint()
                       throws MonetDBEmbeddedException

Creates an unnamed savepoint in the current transaction and returns the new Savepoint object that represents it. WARNING You must turn the autocommit mode off (which is enabled by default to use Savepoints!) or start a transaction.

Returns:

the new Savepoint object

Throws:

MonetDBEmbeddedException - if a database access error occurs or this Connection object is currently in auto-commit mode

setSavepoint

public Savepoint setSavepoint(String name)
                       throws MonetDBEmbeddedException

Creates a savepoint with the given name in the current transaction and returns the new Savepoint object that represents it. WARNING You must turn the autocommit mode off (which is enabled by default to use Savepoints!) or start a transaction.

Parameters:

name - a String containing the name of the savepoint

Returns:

the new Savepoint object

Throws:

MonetDBEmbeddedException - if a database access error occurs or this connection object is currently in auto-commit mode

releaseSavepoint

public void releaseSavepoint(Savepoint savepoint)
                      throws MonetDBEmbeddedException

Removes the given Savepoint object from the current transaction. Any reference to the savepoint after it have been removed will cause an MonetDBEmbeddedException to be thrown.

Parameters:

savepoint - the Savepoint object to be removed

Throws:

MonetDBEmbeddedException - if a database access error occurs or the given Savepoint object is not a valid savepoint in the current transaction

rollback

public void rollback(Savepoint savepoint)
              throws MonetDBEmbeddedException

Undoes all changes made after the given Savepoint object was set. This method should be used only when auto-commit has been disabled.

Parameters:

savepoint - the Savepoint object to roll back to

Throws:

MonetDBEmbeddedException - if a database access error occurs, the Savepoint object is no longer valid, or this Connection object is currently in auto-commit mode

executeUpdate

public int executeUpdate(String query)
                  throws MonetDBEmbeddedException

Executes a SQL query without a result set, returning the number of rows it affected.

Parameters:

query - The SQL query string

Returns:

The number of rows affected

Throws:

MonetDBEmbeddedException - If an error in the database occurred

executeQuery

public QueryResultSet executeQuery(String query)
                            throws MonetDBEmbeddedException

Executes a SQL query with a result set.

Parameters:

query - The SQL query string

Returns:

The query result object

Throws:

MonetDBEmbeddedException - If an error in the database occurred

prepareStatement

public MonetDBEmbeddedPreparedStatement prepareStatement(String query)
                                                  throws MonetDBEmbeddedException

Starts a prepared statement.

Parameters:

query - The SQL query string

Returns:

A prepared statement object where the user will set the parameters

Throws:

MonetDBEmbeddedException - If an error in the database occurred

Since:

2.30

getMonetDBTable

public MonetDBTable getMonetDBTable(String schemaName,
                                    String tableName)
                             throws MonetDBEmbeddedException

Retrieves a database table for further operations on it such as appending data.

Parameters:

schemaName - The schema of the table

tableName - The name of the table

Returns:

A MonetDBTable instance with column details

Throws:

MonetDBEmbeddedException - If an error in the database occurred

getMonetDBTable

public MonetDBTable getMonetDBTable(String tableName)
                             throws MonetDBEmbeddedException

Retrieves a MonetDB Table in the current schema for further operations.

Parameters:

tableName - The name of the table

Returns:

A MonetDBTable instance with column details

Throws:

MonetDBEmbeddedException - If an error in the database occurred

listTables

public QueryResultSet listTables(boolean listSystemTables)
                          throws MonetDBEmbeddedException

Performs a listing of the existing tables with schemas.

Parameters:

listSystemTables - List system's tables as well (default true)

Returns:

The query result object, null if the database is not running

Throws:

MonetDBEmbeddedException - If an error in the database occurred

checkIfTableExists

public boolean checkIfTableExists(String schemaName,
                                  String tableName)
                           throws MonetDBEmbeddedException

Check if a table exists in the database.

Parameters:

schemaName - The schema of the table

tableName - The name of the table

Returns:

If a the table exists or not

Throws:

MonetDBEmbeddedException - If an error in the database occurred

removeTable

public void removeTable(String schemaName,
                        String tableName)
                 throws MonetDBEmbeddedException

Deletes a table if exists in the database.

Parameters:

schemaName - The schema of the table

tableName - The name of the table

Throws:

MonetDBEmbeddedException - If an error in the database occurred

closeConnectionImplementation

protected void closeConnectionImplementation()

When the database shuts down, this method is called instead

toString

public String toString()

A brief description of the connection.

Overrides:

toString in class Object

close

public void close()

Shuts down this connection. Any pending queries connections will be immediately closed as well.

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

finalize

protected void finalize()
                 throws Throwable

Overriding the finalize method to close the connection

Overrides:

finalize in class Object

Throws:

Throwable