--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/jdbcpgbackup/Constraint.java	Thu Mar 21 19:15:52 2019 -0600
@@ -0,0 +1,135 @@
+/*	Copyright (c) 2012	Tomislav Gountchev <tomi@gountchev.net>	*/
+
+package jdbcpgbackup;
+
+import java.sql.Connection;
+import java.sql.PreparedStatement;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.util.ArrayList;
+import java.util.List;
+
+final class Constraint extends DbBackupObject {
+
+	static class ConstraintFactory implements DBOFactory<Constraint> {
+
+		@Override
+		public Iterable<Constraint> getDbBackupObjects(Connection con, Schema schema) throws SQLException {
+			List<Constraint> constraints = new ArrayList<Constraint>();
+			PreparedStatement stmt = null;
+			try {
+				stmt = con.prepareStatement(
+						"SELECT c.oid, c.conname, p.relname, pg_get_userbyid(p.relowner) AS owner, " +
+								"pg_get_constraintdef(c.oid) AS constraintdef, c.contype " +
+								"FROM pg_constraint c, pg_class p " +
+								"WHERE c.connamespace = ? " +
+								"AND c.conrelid = p.oid " +
+						"ORDER BY c.contype DESC");
+				stmt.setInt(1, schema.getOid());
+				ResultSet rs = stmt.executeQuery();
+				while (rs.next()) {
+					constraints.add(new Constraint(rs.getString("conname"), schema, rs.getString("relname"),
+							rs.getString("owner"), rs.getString("constraintdef"), rs.getString("contype").charAt(0)));
+				}
+				rs.close();
+			} finally {
+				if (stmt != null) stmt.close();
+			}
+			return constraints;
+		}
+
+		@Override
+		public Constraint getDbBackupObject(Connection con, String constraintName, Schema schema) throws SQLException {
+			Constraint constraint = null;
+			PreparedStatement stmt = null;
+			try {
+				stmt = con.prepareStatement(
+						"SELECT c.oid, c.conname, p.relname, pg_get_userbyid(p.relowner) AS owner, " +
+								"pg_get_constraintdef(c.oid) AS constraintdef, c.contype " +
+								"FROM pg_constraint c, pg_class p " +
+								"WHERE c.connamespace = ? " +
+								"AND c.conrelid = p.oid " +
+						"AND c.conname = ? ");
+				stmt.setInt(1, schema.getOid());
+				stmt.setString(2, constraintName);
+				ResultSet rs = stmt.executeQuery();
+				if (rs.next()) {
+					constraint = new Constraint(constraintName, schema, rs.getString("relname"),
+							rs.getString("owner"), rs.getString("constraintdef"), rs.getString("contype").charAt(0));
+				} else {
+					throw new RuntimeException("no such constraint: " + constraintName);
+				}
+				rs.close();
+			} finally {
+				if (stmt != null) stmt.close();
+			}
+			return constraint;
+		}
+
+	}
+
+	static class CachingConstraintFactory extends CachingDBOFactory<Constraint> {
+
+		private final Table.CachingTableFactory tableFactory;
+
+		protected CachingConstraintFactory(Schema.CachingSchemaFactory schemaFactory, Table.CachingTableFactory tableFactory) {
+			super(schemaFactory);
+			this.tableFactory = tableFactory;
+		}
+
+		@Override
+		protected PreparedStatement getAllStatement(Connection con) throws SQLException {
+			return con.prepareStatement(
+					"SELECT c.oid, c.conname, c.conrelid AS table_oid, " +
+							"pg_get_constraintdef(c.oid) AS constraintdef, " +
+							"c.connamespace AS schema_oid, c.contype " +
+					"FROM pg_constraint c");
+		}
+
+		@Override
+		protected Constraint newDbBackupObject(Connection con, ResultSet rs, Schema schema) throws SQLException {
+			Table table = tableFactory.getTable(rs.getInt("table_oid"));
+			return new Constraint(rs.getString("conname"), schema, table.getName(),
+					table.getOwner(), rs.getString("constraintdef"), rs.getString("contype").charAt(0));
+		}
+
+		// get the primary key constraints before the rest
+		@Override
+		public final Iterable<Constraint> getDbBackupObjects(Connection con, Schema schema) throws SQLException {
+			Iterable<Constraint> constraints = super.getDbBackupObjects(con, schema);
+			List<Constraint> pklist = new ArrayList<Constraint>();
+			List<Constraint> fklist = new ArrayList<Constraint>();
+			for (Constraint constraint : constraints) {
+				if (constraint.type == 'p') pklist.add(constraint);
+				else fklist.add(constraint);
+			}
+			pklist.addAll(fklist);
+			return pklist;
+		}
+
+	}
+
+	private final String tableName;
+	private final String definition;
+	private final char type;
+
+	private Constraint(String name, Schema schema, String tableName, String tableOwner, String definition, char type) {
+		super(name, schema, tableOwner);
+		this.tableName = tableName;
+		this.definition = definition.replace(" REFERENCES " + schema.getName() + ".", " REFERENCES "); // remove schema name
+		this.type = type;
+	}
+
+	@Override
+	protected StringBuilder appendCreateSql(StringBuilder buf) {
+		buf.append("ALTER TABLE ");
+		buf.append(tableName);
+		buf.append(" ADD CONSTRAINT ");
+		buf.append(name);
+		buf.append(" ");
+		buf.append(definition);
+		buf.append(" ;\n");
+		return buf;
+	}
+
+}