2013/1/31 Vincent Veyron <vv.lists@xxxxxxxxxx>: > Le jeudi 31 janvier 2013 à 11:06 +0100, Pavel Stehule a écrit : >> 2013/1/31 Vincent Veyron <vv.lists@xxxxxxxxxx>: >> > >> > Suppose I have a query of the form >> > >> > SELECT my_function(column_1), column_2 >> > FROM my_table >> > GROUP BY my_function(column_1) >> > ORDER BY my_function(column_1); >> > >> > where my_function is a user defined function. >> > >> > How many times is the function computed? >> >> if function is stable or immutable, then once per row >> > > In this post (watch for line-wrap) : > > http://www.postgresql.org/message-id/CAFj8pRAdYL1-hCxH > +QSZQKHt9YnoaOiGkfX4cNc9mzUTimcs1w@xxxxxxxxxxxxxx > > you wrote that it is usually better not to mark SQL functions (as > opposed to plpgsql functions). > > So should I mark SQL functions stable/immutable if I use them in a query > like the one above, or is it unnecessary? > It should not be marked Regards Pavel > > -- > Salutations, Vincent Veyron > http://marica.fr/site/demonstration > Logiciel de gestion des contentieux juridiques et des sinistres d'assurance > -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
