TEST-TAP: Experiment metadata extraction from the database.

package tap.metadata;

/*

 * This file is part of TAPLibrary.

 * 

 * TAPLibrary is free software: you can redistribute it and/or modify

 * it under the terms of the GNU Lesser General Public License as published by

 * the Free Software Foundation, either version 3 of the License, or

 * (at your option) any later version.

 * 

 * TAPLibrary is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU Lesser General Public License for more details.

 * 

 * You should have received a copy of the GNU Lesser General Public License

 * along with TAPLibrary.  If not, see <http://www.gnu.org/licenses/>.

 * 

 * Copyright 2014 - Astronomisches Rechen Institute (ARI)

 */

import java.sql.Connection;

import java.sql.DatabaseMetaData;

import java.sql.DriverManager;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.sql.Statement;

/**

 * @author Grégory Mantelet (ARI) - gmantele@ari.uni-heidelberg.de

 * @version 1.1 (04/2014)

 */

public class MetadataExtractionTest {

	public static void main(String[] args) throws Throwable{

		MetadataExtractionTest extractor = new MetadataExtractionTest();

		try{

			extractor.connect();

			extractor.printTableMetadata("gums");

		}finally{

			extractor.close();

		}

	}

	private Connection connection = null;

	private Statement statement = null;

	public void connect(){

		try{

			Class.forName("org.postgresql.Driver");

			connection = DriverManager.getConnection("jdbc:postgresql:gmantele", "gmantele", "pwd");

			statement = connection.createStatement();

			System.out.println("[OK] DB connection successfully established !");

		}catch(ClassNotFoundException notFoundException){

			notFoundException.printStackTrace();

			System.err.println("[ERROR] Connection error !");

		}catch(SQLException sqlException){

			sqlException.printStackTrace();

			System.err.println("[ERROR] Connection error !");

		}

	}

	public ResultSet query(String requet){

		ResultSet resultat = null;

		try{

			resultat = statement.executeQuery(requet);

		}catch(SQLException e){

			e.printStackTrace();

			System.out.println("Erreur dans la requête: " + requet);

		}

		return resultat;

	}

	public TAPSchema printTableMetadata(final String table){

		try{

			DatabaseMetaData dbMeta = connection.getMetaData();

			TAPSchema tapSchema = null;

			TAPTable tapTable = null;

			// Extract Table metadata (schema, table, type):

			ResultSet rs = dbMeta.getTables(null, null, table, null);

			rs.last();

			if (rs.getRow() == 0)

				System.err.println("[ERROR] No found table for \"" + table + "\" !");

			else if (rs.getRow() > 1){

				rs.first();

				System.err.println("[ERROR] More than one match for \"" + table + "\":");

				while(rs.next())

					System.err.println(rs.getString(2) + "." + rs.getString(3) + " : " + rs.getString(4));

			}else{

				rs.first();

				tapSchema = new TAPSchema(rs.getString(2));

				tapTable = new TAPTable(rs.getString(3), rs.getString(4));

				tapSchema.addTable(tapTable);

				System.out.println("[OK] 1 table FOUND ! => " + tapTable + " : " + tapTable.getType());

			}

			// Extract all columns metadata (type, precision, scale):

			rs = dbMeta.getColumns(null, tapSchema.getDBName(), tapTable.getDBName(), null);

			String type;

			while(rs.next()){

				type = rs.getString(6);

				if (type.endsWith("char") || type.equals("numeric")){

					type += "(" + rs.getInt(7);

					if (type.startsWith("numeric"))

						type += "," + rs.getInt(9);

					type += ")";

				}

				System.out.println("    * " + rs.getString(4) + " : " + type);

			}

			// Extract all indexed columns:

			rs = dbMeta.getIndexInfo(null, tapSchema.getDBName(), tapTable.getDBName(), false, true);

			while(rs.next()){

				System.out.println("    # " + rs.getString(6) + " : " + rs.getShort(7) + " (unique ? " + (!rs.getBoolean(4)) + ") -> " + rs.getString(9) + " => " + rs.getInt(11) + " unique values in the index ; " + rs.getInt(12) + " pages");

			}

			return tapSchema;

		}catch(SQLException e){

			e.printStackTrace();

			return null;

		}

	}

	public void close(){

		try{

			connection.close();

			statement.close();

			System.out.println("[OK] Connection closed !");

		}catch(SQLException e){

			e.printStackTrace();

			System.out.println("[ERROR] Connection CAN NOT be closed !");

		}

	}

}