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Postgres 7.0 JDBC - update count for DELETE is always 1

From: Stephen Crawley <crawley(at)dstc(dot)edu(dot)au>
To: pgsql-interfaces(at)postgresql(dot)org
Subject: Postgres 7.0 JDBC - update count for DELETE is always 1
Date: 2000-06-05 00:38:57
Message-ID: 200006050038.e550coo17653@piglet.dstc.edu.au (view raw or flat)
Thread:
Lists: pgsql-interfaces
Hi,

I'm trying to port a large JDBC application to Postgres 7.0 from MySQL,
and I've run into what I believe is a bug in the JDBC driver.

When my application executes a "DELETE" statement, the ResultSet entry
always says that 1 row has been deleted.  Even when nothing has been
deleted.  I did a bit of investigation, and I think I've found where the
problem is.  In the class postgresql.Connection, the method 

   public java.sql.ResultSet ExecSQL(String sql) throws SQLException

contains the following code:

  ...

  int update_count = 1;

  ...		
	
  case 'C':	// Command Status
    recv_status = pg_stream.ReceiveString(8192);
				
    // Now handle the update count correctly.
    if(recv_status.startsWith("INSERT") || recv_status.startsWith("UPDATE")) {
      try {
       update_count = 
         Integer.parseInt(recv_status.substring(1+recv_status.lastIndexOf(' 
')));
      } catch(NumberFormatException nfe) {
      throw new PSQLException("postgresql.con.fathom",recv_status);
      }
    }

  ...

It looks like the code picks out the update count when the query was
described (by the backend) as an INSERT or UPDATE.  But it does not
do this for a DELETE.

I looked at the source of the backend (src/backend/tcop/dest.c, etc) and
it does seem to return an update count for the CMD_DELETE command.  If
I've got this right, adding

   ... || recv_status.startsWith("DELETE") ...

to the if statement should fix the problem.

-- Steve

  


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