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interface JDBCDialect {
	// new APIs
	String getListTablesStatement(String database);
	
	String getListDatabasesStatement();

	String getTableMetadataStatement();
}

public JDBCCatalog extends AbstractCatalog {
	

	public JDBCCatalog(String catalogName, String defaultDatabase, String userName, String pwd, String baseUrl) 

	void open() {
		// verify jdbc connection to fail earlier
	}

	void close();
}

public PostgresJDBCCatalog extends AbstractJDBCCatalog {
	PostgresJDBCCatalog	PostgresDialect() {
		// new impls

		String getListTablesStatement(String database) { ... }
	
		String getListDatabasesStatement() { ... }

		String getTableMetadataStatement() { ... }
	}

	DerbyDialect {
		String getListTablesStatement(String database) { // unsupported exception }
	
		String getListDatabasesStatement() { // unsupported exception }

		String getTableMetadataStatement() { // unsupported exception }
	}

	...
}



public JDBCCatalog extends AbstractCatalog {
	JDBCDialect dialect;
	InternalJDBCCatalog internal;
	
	public JDBCCatalog(String catalogName, String defaultDatabase, String userName, String pwd, String baseUrl) {
		JDBCDialect d = JDBCDialects.get(baseUrl).get();

		switch(d) {
			case postgres:
				internal = new PostgresJDBCCatalog(...);
				break;
			case derby:
				...
		}
	} 

	List<String>void listDatabasesopen() {
		// translate to "SELECT datname FROM pg_database;"verify jdbc connection to fail earlier
	}

	void close();

	List<String> listDatabases() {
		// execute and parse dialect.getListDatabasesStatement();
	}

	boolean databaseExists(String dbname) {
		return listDatabases.contains(dbname);
	}

	CatalogTableboolean getTabletableExists(ObjectPath oppath) {
		// translate to result set metadata of "SELECT * FROM <tablename>;"databaseExists(path.getDatabaseName())
		return listTables().contains(path.getObjectName());
	}

	List<String> listDatabases() {
		return internal.listDatabases();
	}

	CatalogTable getTable(ObjectPath op) {
		return internal.getTable(op);
	}

	List<String> listTables(String db) {
		for each db in listDatabases:
			// translate to "SELECT * FROM information_schema.tables
						WHERE table_type = 'BASE TABLE' AND table_schema = <schema_name>
						ORDER BY table_type, table_name;"return internal.listTables(db);
	}
}

public InternalPostgresJDBCCatalog extends InternalJDBCCatalog {
	JDBCDialect dialect;

	protected PostgresJDBCCatalog(String catalogName, String defaultDatabase, String userName, String pwd, String baseUrl) {
		dialect = new PostgresDialect();
	}

	List<String> listDatabases() {
		// execute and parse dialect.getListDatabasesStatement();
	}

	booleanCatalogTable tableExistsgetTable(ObjectPath pathop) {
		databaseExists(path.getDatabaseName())
		return listTables().contains(path.getObjectName())// execute and parse dialect.getTableMetadataStatement();
		// map data types and build catalog table
	}

	List<String> listTables() {
		// execute and parse dialect.getListTablesStatement();
	}
}