Le jeudi 31 janvier 2013 à 09:49 +0100, Pavel Stehule a écrit : > any join where result is related to some function result can be very > slow, because estimation will be out and any repeated function > evaluation is just expensive. > Hi Pavel, Thank you for the correction. Since we're at it, I have a question regarding functions in a query : 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? -- 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
