--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/luan/modules/lucene/PostgresBackup.java	Mon Sep 02 22:23:12 2019 -0600
@@ -0,0 +1,180 @@
+package luan.modules.lucene;
+
+import java.sql.Connection;
+import java.sql.DriverManager;
+import java.sql.Statement;
+import java.sql.PreparedStatement;
+import java.sql.SQLException;
+import java.util.Properties;
+import luan.LuanTable;
+import luan.LuanException;
+import luan.modules.parsers.LuanToString;
+import luan.lib.logging.Logger;
+import luan.lib.logging.LoggerFactory;
+
+
+final class PostgresBackup {
+	private static final Logger logger = LoggerFactory.getLogger(PostgresBackup.class);
+
+	static PostgresBackup newInstance() {
+		try {
+			return new PostgresBackup();
+		} catch(ClassNotFoundException e) {
+			logger.error("creation failed",e);
+			return null;
+		} catch(SQLException e) {
+			logger.error("creation failed",e);
+			return null;
+		}
+	}
+
+	final boolean wasCreated;
+	private final Connection con;
+	private final PreparedStatement insertStmt;
+	private final PreparedStatement updateStmt;
+	private final PreparedStatement deleteStmt;
+	private int trans = 0;
+
+	private PostgresBackup()
+		throws ClassNotFoundException, SQLException
+	{
+		Class.forName("org.postgresql.Driver");
+
+		String url = "jdbc:postgresql://localhost:5432/luan";
+		Properties props = new Properties();
+		props.setProperty("user","postgres");
+		props.setProperty("password","");
+
+		con = DriverManager.getConnection(url,props);
+
+		Statement stmt = con.createStatement();
+		boolean hasTable = stmt.executeQuery(
+			"select * from information_schema.tables where table_name='lucene'"
+		).next();
+		if( !hasTable ) {
+			stmt.executeUpdate(
+				"create table lucene ("
+				+"	id integer not null primary key,"
+				+"	data text not null"
+				+")"
+			);
+		}
+		stmt.close();
+		wasCreated = !hasTable;
+
+		insertStmt = con.prepareStatement(
+			"insert into lucene (id,data) values (?,?)"
+		);
+		updateStmt = con.prepareStatement(
+			"update lucene set data=? where id=?"
+		);
+		deleteStmt = con.prepareStatement(
+			"delete from lucene where id=?"
+		);
+	}
+
+	void close() {
+		try {
+			insertStmt.close();
+			updateStmt.close();
+			deleteStmt.close();
+			con.close();
+		} catch(SQLException e) {
+			logger.error("close failed",e);
+		}
+	}
+
+	protected void finalize() throws Throwable {
+		super.finalize();
+		if( !con.isClosed() ) {
+			logger.error("con not closed");
+			con.close();
+		}
+	}
+
+	void add(long id,LuanTable doc) throws LuanException {
+		try {
+//logger.info("getAutoCommit="+con.getAutoCommit());
+			String data = LuanToString.toString(doc,true);
+			insertStmt.setLong(1,id);
+			insertStmt.setString(2,data);
+			insertStmt.executeUpdate();
+		} catch(SQLException e) {
+			logger.error("add failed",e);
+		}
+	}
+
+	void update(long id,LuanTable doc) throws LuanException {
+		try {
+			String data = LuanToString.toString(doc,true);
+			updateStmt.setString(1,data);
+			updateStmt.setLong(2,id);
+			int n = updateStmt.executeUpdate();
+			if( n==0 ) {
+				logger.error("update not found for id="+id+", trying add");
+				add(id,doc);
+			} else if( n!=1 )
+				throw new RuntimeException();
+		} catch(SQLException e) {
+			logger.error("update failed",e);
+		}
+	}
+
+	void deleteAll() {
+		try {
+			Statement stmt = con.createStatement();
+			stmt.executeUpdate("delete from lucene");
+			stmt.close();
+		} catch(SQLException e) {
+			logger.error("update failed",e);
+		}
+	}
+
+	void delete(long id) {
+		try {
+			deleteStmt.setLong(1,id);
+			int n = deleteStmt.executeUpdate();
+			if( n==0 ) {
+				logger.error("delete not found for id="+id);
+			}
+		} catch(SQLException e) {
+			logger.error("update failed",e);
+		}
+	}
+
+	void begin() {
+		try {
+			if( trans++ == 0 )
+				con.setAutoCommit(false);
+		} catch(SQLException e) {
+			logger.error("begin failed",e);
+		}
+	}
+
+	void commit() {
+		try {
+			if( trans <= 0 ) {
+				logger.error("commit not in transaction");
+				return;
+			}
+			if( --trans == 0 )
+				con.setAutoCommit(true);
+		} catch(SQLException e) {
+			logger.error("begin failed",e);
+		}
+	}
+
+	void rollback() {
+		try {
+			if( --trans != 0 ) {
+				logger.error("rollback failed trans="+trans);
+				return;
+			}
+			con.rollback();
+			con.setAutoCommit(true);
+		} catch(SQLException e) {
+			logger.error("begin failed",e);
+		}
+	}
+
+}