ERROR: duplicate key value violates unique constraint "xak1fact_dim_relationship"

I am getting the below error while deleting some rows and updating the table based on a condition from java. My database is PostgreSQL 8.4. Below is the error: ERROR: duplicate key value violates unique constraint "xak1fact_dim_relationship"

The code cuasing this issue is below:

/**
 * Commits job.  This does the following:
 * <OL>
 *  <LI> cancel previous datamart states </LI>
 *  <LI> drop diabled derived objects </LI>
 *  <LI> flip mirror relationships for objects with next states </LI>
 *  <LI> advance rolloff_state from start1 to complete1, from start2 to complete </LI>
 *  <LI> set 1/0 internal states to 0/-1 </LI>
 *  <LI> remove header objects with no letter rows </LI>
 *  <LI> mark mirror rel as OS if children are missing (e.g., semantic w/o agg build) </LI>
 *  <LI> mark mirror rel as OS if int-map not in sync with dim base (e.g., int-map SQL w/o semantic) </LI>
 * </OL>
 */
protected void CommitJobUnprotected()
    throws SQLException
{
    if (_repl.epiCenterCon== null)
        throw makeReplacementError(0);
    boolean oldAutoCommitStatus = _repl.epiCenterCon.getAutoCommit();

    try
    {

        _repl.epiCenterCon.setAutoCommit(false);

        Statement stmt = null;
        boolean committed = false;
        synchronized (SqlRepl.metaChangeLock)
        {
            try
            {
                stmt = _repl.epiCenterCon.createStatement();

                // update internal states for fact_dim_relationship
   开发者_开发问答             metaExec(stmt, "DELETE from fact_dim_relationship WHERE internal_state = -1 AND "  +
                                " EXISTS (SELECT 1 FROM fact_dim_relationship WHERE internal_state = 1)",
                                " SELECT 1 from fact_dim_relationship WHERE internal_state = -1 AND "  +
                                " EXISTS (SELECT 1 FROM fact_dim_relationship WHERE internal_state = 1)"); /*1*/
                metaExec( stmt, "UPDATE fact_dim_relationship SET internal_state = internal_state - 1 " +
                             " WHERE EXISTS (SELECT 1 FROM fact_dim_relationship inner1 " +
                             "              WHERE inner1.internal_state = 1 " +
                             " AND inner1.fact_tbl_key = fact_dim_relationship.fact_tbl_key " +
                             " AND inner1.dim_base_key = fact_dim_relationship.dim_base_key ) ",
                             " SELECT 1 FROM fact_dim_relationship " +
                             " WHERE EXISTS (SELECT 1 FROM fact_dim_relationship inner1 " +
                             "              WHERE inner1.internal_state = 1 " +
                             " AND inner1.fact_tbl_key = fact_dim_relationship.fact_tbl_key " +
                             " AND inner1.dim_base_key = fact_dim_relationship.dim_base_key ) "); /*5*/

                System.out.println("Update done on fact_dim_relationship");
                _repl.doDrop(SqlReplLogger.DB_META, stmt, "fact_agg", "SELECT fact_agg_key FROM fact_agg f WHERE " +
                                                                      " NOT EXISTS (SELECT 1 FROM fact_agg_letter l WHERE " +
                                                                      "                 f.fact_agg_key = l.fact_agg_key) "); /*6*/

                _repl.doDrop(SqlReplLogger.DB_META, stmt, "dim_base_agg", "SELECT dim_base_agg_key FROM dim_base_agg d WHERE " +
                                                                          " NOT EXISTS (SELECT 1 FROM dim_base_agg_letter l WHERE " +
                                                                          "                 d.dim_base_agg_key = l.dim_base_agg_key) "); /*6*/

                CheckOutOfSync(stmt, "fact_agg", null); /*7*/
                CheckOutOfSync(stmt, "dim_base_agg", null); /*7*/

                metaExec( stmt, " update mirror_relationship set relation_to_current = 'Out Of Sync' " +
                                " where dim_col_intmap_key is not null " +
                                " and relation_to_current = 'One Back' " +
                                " and not exists ( " +
                                "       select 1 " +
                                "       from mirror_relationship m2, dim_col_view c, dim_col_intmap i " +
                                "       where m2.dim_base_key = c.dim_base_key " +
                                "       and c.dim_col_key = i.dim_col_key  " +
                                "       and i.dim_col_intmap_key = mirror_relationship.dim_col_intmap_key " +
                                "       and m2.relation_to_current = 'One Back') ",
                                " SELECT 1 FROM mirror_relationship " +
                                " where dim_col_intmap_key is not null " +
                                " and relation_to_current = 'One Back' " +
                                " and not exists ( " +
                                "       select 1 " +
                                "       from mirror_relationship m2, dim_col_view c, dim_col_intmap i " +
                                "       where m2.dim_base_key = c.dim_base_key " +
                                "       and c.dim_col_key = i.dim_col_key  " +
                                "       and i.dim_col_intmap_key = mirror_relationship.dim_col_intmap_key " +
                                "       and m2.relation_to_current = 'One Back') "); /*8*/

                // clean out the tables used by mombuilder, aggbuilder, and semantics
                metaExec( stmt,  "delete from relation_intermediary", "select 1 from relation_intermediary" );

                _repl.epiCenterCon.commit();
                committed = true;
            }
            finally
            {

                safeMetaRollbackIfNeeded( committed );
                _repl.safeClose( null, stmt );
            }
        } // end synchronized block
    }
    finally
    {
        _repl.epiCenterCon.setAutoCommit(oldAutoCommitStatus);
    }
}

The first delete statement ran well, but while running the update it is throwing the above exception....! We support the SQLServer, Oracle and DB2, and the same code runs fine with other DBs. By the way we run these statements in a READ_COMMITTED transaction level and we are setting the autocommit off if anything fails in between we safely rolls back. If i run the above code with autocommit true the code works fine! But we should not do so. I am suspecting the Multi version concurrency control feature of PostgreSQL, am i wrongly setting the Isolation level? Please help me as early as possible. I can provide what ever the info you want.

If it is only this particular set of queries, use SET CONSTRAINT:

BEGIN;
SET CONSTRAINT = xak1fact_dim_relationship DEFERRED;
-- Do your SQL
COMMIT;

If this is a very common case, you can change your database schema to you can, change your database schema to support INITIALLY DEFERRED.