Re: A little RULE help?

Achilleas Mantzios <achill@xxxxxxxxxxxxxxxxxxxxx> · Wed, 31 Jan 2018 18:17:48 +0200



    On 31/01/2018 18:02, David G. Johnston
      wrote:

    
        On Wed, Jan 31, 2018 at
            8:39 AM, Steven Winfield <Steven.Winfield@xxxxxxxxxxxxxxxxx> wrote:

        
                      Don't use RULEs.

                      -- 

                      Vik Fearing +33 6 46 75 15 36

                      http://2ndQuadrant.fr
                      PostgreSQL : Expertise, Formation et Support
                     
                     
                  Repeating
                      this, as if I should already know this, is less
                      helpful though. It’s not as if the docs tells
                      users to steer clear of RULEs.
                    
                  If
                      there is something I don’t understand, such as
                      RULEs, I prefer to experiment with it and ask
                      questions if there is something I still don’t
                      follow. I thought this was the correct forum for
                      those questions.
                   
                
          The docs do
            suggest that rules are more difficult to do correctly.
          

          https://www.postgresql.org/docs/10/static/rules-triggers.html
          

          Few people
            use them which means they generally get less exposure to a
            variety of circumstances during feature testing and use and
            the long-term maintenance dynamics are larger.
          

          That all
            said, if you can justify your use of them in a particular
            context you should probably just ignore those saying not to
            use them without the same knowledge of your situation.  The
            reward may be worth the risk/cost but the people yelling out
            for you to be careful are not doing so for the fun of it. 
            You should at least heed it to the point of saying, "yes,
            I'm sure I want to do this".
        
      
    We have used RULEs to handle insertions / deletions from non-trivial
    views. And I can give this example if anyone wants.

    
    Also we have used views to ignite smth like :

    CREATE RULE account_credit_ins AS

        ON INSERT TO account_credit DO INSTEAD  SELECT
    public.rule_disable('INSERT'::text) AS rule_disable;

    where rule_disable is a function that just raises an exception with
    some diagnostic text.

    
    We dont make heavey use of RULEs, but I think they have their place.

    
          David J.
        
      
    -- 
Achilleas Mantzios
IT DEV Lead
IT DEPT
Dynacom Tankers Mgmt