Hi, following I tried for some application logic based data migration Statement stmt = dbCon.createStatement(); try { ResultSet geo_columns_rs = stmt. executeQuery("SELECT baseline_check_version from geodb limit 1"); source_version = Versions.R03_00; source_version = Versions.R03_00; }catch (Exception e) {} to check if column already exists... If I get an exception in Java I remember that and try to update my database structure to new version using following: dbCon.createStatement().execute("ALTER TABLE geodb ADD COLUMN baseline_check_version VARCHAR(32)"); If I do so I get following error by Postgres: org.postgresql.util.PSQLException: ERROR: current transaction is aborted, commands ignored until end of transaction block at org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse(QueryExecutorImpl.java:1512) at org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:1297) at org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:188) at org.postgresql.jdbc2.AbstractJdbc2Statement.execute(AbstractJdbc2Statement.java:437) at org.postgresql.jdbc2.AbstractJdbc2Statement.executeWithFlags(AbstractJdbc2Statement.java:339) at org.postgresql.jdbc2.AbstractJdbc2Statement.execute(AbstractJdbc2Statement.java:331) at de.airbus.omts.geodbgen.communication.dbms.Checker.execute(Checker.java:244) at de.airbus.omts.geodbgen.communication.dbms.Checker.migrateDB(Checker.java:206) at de.airbus.omts.geodbgen.communication.dbms.Checker.main(Checker.java:390) To work around this I add an dbCon.rollBack() after select statement above in good and in bad times. After that ALTER works. Can someone explain me why I need this rollback ? Using: Postgres 8.1.4-1, JDBC postgresql-8.1-405.jdbc3, JDK 1.6 Same problem with JDK 1.5... Thanks thomas -- Mit freundlichen Grüßen Brunel GmbH Dipl.-Inf. Thomas Carsten Franke - Senior Software Designer - Brunel GmbH Bereich Communications Daimlerring 9 D 31135 Hildesheim, Germany Telefon: 05121 1760-820 Telefax: 05121 1760-999 E-Mail: Thomas-Carsten.Franke@xxxxxxxxx Internet: www.brunel.de Hauptsitz: Airport City, Hermann-Köhl-Str. 1 a, 28199 Bremen Amtsgericht Bremen HRB 16935 General Manager: Carsten Siebeneich ---------------------------(end of broadcast)--------------------------- TIP 2: Don't 'kill -9' the postmaster