FAQ

        UNION ALL
        SELECT tab1.col1, NULL
        FROM tab1
        WHERE tab1.col1 NOT IN (SELECT tab2.col1 FROM tab2)
        ORDER BY tab1.col1
     _________________________________________________________________
   
                            Extending PostgreSQL
                                      
    5.1) I wrote a user-defined function. When I run it in psql, why does it
    dump core?
    
   The problem could be a number of things. Try testing your user-defined
   function in a stand alone test program first.
   
    5.2) What does the message: NOTICE:PortalHeapMemoryFree: 0x402251d0 not in
    alloc set! mean?
    
   You are pfree'ing something that was not palloc'ed. Beware of mixing
   malloc/free and palloc/pfree.
   
    5.3) How can I contribute some nifty new types and functions for
    PostgreSQL?
    
   Send your extensions to the pgsql-hackers mailing list, and they will
   eventually end up in the contrib/ subdirectory.
   
    5.4) How do I write a C function to return a tuple?
    
   This requires wizardry so extreme that the authors have never tried
   it, though in principle it can be done.
   
    5.5) I have changed a source file. Why does the recompile does not see the
    change?
    
   The Makefiles do not have the proper dependencies for include files.
   You have to do a make clean and then another make. You have to do a
   make clean and then another make.