データベースAにデータを作成し、レプリケーションを介してデータベースBにコピーすることができます。
または、ある種のキューを実装しているようです。私はかつてJavaでデータコピープログラムを構築しました。これは、キューインターフェイスの組み込み実装を使用していました。データベースAからデータを読み取ってキューを埋めるスレッドと、キューから読み取ってデータベースBに書き込むスレッドがありました。使用したクラスを掘り下げることができますか？
編集：
これが、公開用に微調整されたコードです。構成クラスは含めていませんが、キュークラスの使用方法がわかるはずです。
package test;
import java.io.File;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
/**
* This class implements a JDBC bridge between databases, allowing data to be
* copied from one place to another.
* <p>This implementation is threaded, as it uses a {@link BlockingQueue} to pass
* data between a producer and a consumer.
*/
public class DBBridge {
public static void main( String[] args ) {
Adaptor fromAdaptor = null;
Adaptor toAdaptor = null;
BridgeConfig config = null;
try {
/* BridgeConfig is essentially a wrapper around the Simple XML serialisation library.
* http://simple.sourceforge.net/
*/
config = BridgeConfig.loadConfig( new File( "db-bridge.xml" ) );
}
catch ( Exception e ) {
System.err.println( "Failed to read or parse db-bridge.xml: " + e.getLocalizedMessage() );
System.exit( 1 );
}
BlockingQueue<Object> b = new ArrayBlockingQueue<Object>( config.getQueueSize() );
try {
HashMap<String, DatabaseConfig> dbs = config.getDbs();
System.err.println( "Configured DBs" );
final String sourceName = config.getSource();
final String destinationName = config.getDestination();
if ( !dbs.containsKey( sourceName ) ) {
System.err.println( sourceName + " is not a configured database connection" );
System.exit( 1 );
}
if ( !dbs.containsKey( destinationName ) ) {
System.err.println( destinationName + " is not a configured database connection" );
System.exit( 1 );
}
DatabaseConfig sourceConfig = dbs.get( sourceName );
DatabaseConfig destinationConfig = dbs.get( destinationName );
try {
/*
* Both adaptors must be created before attempting a connection,
* as otherwise I've seen DriverManager pick the wrong driver!
*/
fromAdaptor = AdaptorFactory.buildAdaptor( sourceConfig, sourceConfig );
toAdaptor = AdaptorFactory.buildAdaptor( destinationConfig, destinationConfig );
System.err.println( "Connecting to " + sourceName );
fromAdaptor.connect();
System.err.println( "Connecting to " + destinationName );
toAdaptor.connect();
/* We'll send our updates to the destination explicitly */
toAdaptor.getConn().setAutoCommit( false );
}
catch ( SQLException e ) {
System.err.println();
System.err.println( "Failed to create and configure adaptors" );
e.printStackTrace();
System.exit( 1 );
}
catch ( ClassNotFoundException e ) {
System.err.println( "Failed to load JDBC driver due to error: " + e.getLocalizedMessage() );
System.exit( 1 );
}
DataProducer producer = null;
DataConsumer consumer = null;
try {
producer = new DataProducer( config, fromAdaptor, b );
consumer = new DataConsumer( config, toAdaptor, b );
}
catch ( SQLException e ) {
System.err.println();
System.err.println( "Failed to create and configure data producer or consumer" );
e.printStackTrace();
System.exit( 1 );
}
consumer.start();
producer.start();
}
catch ( Exception e ) {
e.printStackTrace();
}
}
public static class DataProducer extends DataLogger {
private BridgeConfig config;
private Adaptor adaptor;
private BlockingQueue<Object> queue;
public DataProducer(BridgeConfig c, Adaptor a, BlockingQueue<Object> bq) {
super( "Producer" );
this.config = c;
this.adaptor = a;
this.queue = bq;
}
@Override
public void run() {
/* The tables to copy are listed in BridgeConfig */
for ( Table table : this.config.getManifest() ) {
PreparedStatement stmt = null;
ResultSet rs = null;
try {
String sql = table.buildSourceSelect();
this.log( "executing: " + sql );
stmt = this.adaptor.getConn().prepareStatement( sql );
stmt.execute();
rs = stmt.getResultSet();
ResultSetMetaData meta = rs.getMetaData();
/* Notify consumer that a new table is to be processed */
this.queue.put( table );
this.queue.put( meta );
final int columnCount = meta.getColumnCount();
while ( rs.next() ) {
ArrayList<Object> a = new ArrayList<Object>( columnCount );
for ( int i = 0; i < columnCount; i++ ) {
a.add( rs.getObject( i + 1 ) );
}
this.queue.put( a );
}
}
catch ( InterruptedException ex ) {
ex.printStackTrace();
}
catch ( SQLException e ) {
// TODO Auto-generated catch block
e.printStackTrace();
}
try {
/* refresh the connection */
/* Can't remember why I can this line - maybe the other
* end kept closing the connection. */
this.adaptor.reconnect();
}
catch ( SQLException e ) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
try {
/* Use an object of a specific type to "poison" the queue
* and instruct the consumer to terminate. */
this.log( "putting finished object into queue" );
this.queue.put( new QueueFinished() );
this.adaptor.close();
}
catch ( InterruptedException e ) {
// TODO Auto-generated catch block
e.printStackTrace();
}
catch ( SQLException e ) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
/* Superclass for producer and consumer */
public static abstract class DataLogger extends Thread {
private String prefix;
public DataLogger(String p) {
this.prefix = p;
}
protected void log( String s ) {
System.err.printf( "%d %s: %s%n", System.currentTimeMillis(), this.prefix, s );
}
protected void log() {
System.err.println();
}
}
public static class DataConsumer extends DataLogger {
private BridgeConfig config;
private Adaptor adaptor;
private BlockingQueue<Object> queue;
private int currentRowNumber = 0;
private int currentBatchSize = 0;
private long tableStartTs = -1;
public DataConsumer(BridgeConfig c, Adaptor a, BlockingQueue<Object> bq) throws SQLException {
super( "Consumer" );
this.config = c;
this.adaptor = a;
this.queue = bq;
/* We'll send our updates to the destination explicitly */
this.adaptor.getConn().setAutoCommit( false );
}
public void printThroughput() {
double duration = ( System.currentTimeMillis() - this.tableStartTs ) / 1000.0;
long rowsPerSec = Math.round( this.currentRowNumber / duration );
this.log( String.format( "%d rows processed, %d rows/s", this.currentRowNumber, rowsPerSec ) );
}
@Override
public void run() {
this.log( "running" );
Table currentTable = null;
ResultSetMetaData meta = null;
int columnCount = -1;
PreparedStatement stmt = null;
while ( true ) {
try {
Object o = this.queue.take();
if ( o instanceof Table ) {
currentTable = (Table) o;
this.log( "processing" + currentTable );
if ( this.currentBatchSize > 0 ) {
/* Commit outstanding rows from previous table */
this.adaptor.getConn().commit();
this.printThroughput();
this.currentBatchSize = 0;
}
/* refresh the connection */
this.adaptor.reconnect();
this.adaptor.getConn().setAutoCommit( false );
/*
* Arguably, there's no need to flush the commit buffer
* after every table, but I like it because it feels
* tidy.
*/
this.currentBatchSize = 0;
this.currentRowNumber = 0;
if ( currentTable.isTruncate() ) {
this.log( "truncating " + currentTable );
stmt = this.adaptor.getConn().prepareStatement( "TRUNCATE TABLE " + currentTable );
stmt.execute();
}
this.tableStartTs = System.currentTimeMillis();
}
else if ( o instanceof ResultSetMetaData ) {
this.log( "received metadata for " + currentTable );
meta = (ResultSetMetaData) o;
columnCount = meta.getColumnCount();
String sql = currentTable.buildDestinationInsert( columnCount );
stmt = this.adaptor.getConn().prepareStatement( sql );
}
else if ( o instanceof ArrayList ) {
ArrayList<?> a = (ArrayList<?>) o;
/* One counter for ArrayList access, one for JDBC access */
for ( int i = 0, j = 1; i < columnCount; i++, j++ ) {
try {
stmt.setObject( j, a.get( i ), meta.getColumnType( j ) );
}
catch ( SQLException e ) {
/* Sometimes data in a shonky remote system
* is rejected by a more sane destination
* system. Translate this data into
* something that will fit. */
if ( e.getMessage().contains( "Only dates between" ) ) {
if ( meta.isNullable( j ) == ResultSetMetaData.columnNullable ) {
this.log( "Casting bad data to null: " + a.get( i ) );
stmt.setObject( j, null, meta.getColumnType( j ) );
}
else {
this.log( "Casting bad data to 0000-01-01: " + a.get( i ) );
stmt.setObject( j, new java.sql.Date( -64376208000L ), meta.getColumnType( j ) );
}
}
else {
throw e;
}
}
}
stmt.execute();
this.currentBatchSize++;
this.currentRowNumber++;
if ( this.currentBatchSize == this.config.getBatchSize() ) {
/*
* We've reached our non-committed limit. Send the
* requests to the destination server.
*/
this.adaptor.getConn().commit();
this.printThroughput();
this.currentBatchSize = 0;
}
}
else if ( o instanceof QueueFinished ) {
if ( this.currentBatchSize > 0 ) {
/* Commit outstanding rows from previous table */
this.adaptor.getConn().commit();
this.printThroughput();
this.log();
this.log( "completed" );
}
/* Exit while loop */
break;
}
else {
throw new RuntimeException( "Unexpected obeject in queue: " + o.getClass() );
}
}
catch ( InterruptedException e ) {
// TODO Auto-generated catch block
e.printStackTrace();
}
catch ( SQLException e ) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
try {
this.adaptor.close();
}
catch ( SQLException e ) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
public static final class QueueFinished {
/*
* This only exists as a completely type-safe value in "instanceof"
* expressions
*/
}
}