Please don't top-post. Inline (with trim) is better but at minimum bottom-post.
On Tue, Jul 14, 2020 at 9:01 AM Marc Millas <marc.mil...@mokadb.com> wrote: > Hi, > your answer helps me understand my first problem. > so, I rewrote a simple loop so as to avoid the "volatile" behaviour. > (at least I was thinking I did... looks like I was wrong !) > step by step loop: > DO $$ > BEGIN > FOR counter IN 1..1000 LOOP > begin > declare > id1 integer =ceiling(random()*2582); > id3 date= '2000-01-01'; > id2 date; > pren varchar; > begin > id2=id3 + (random()*7200)::integer; > SELECT prenom FROM prenoms WHERE id=id1 into pren; > INSERT INTO testparttransac (datenaissance, prenoms) values(id2,pren); > end; > end; > END LOOP; > END; $$; > > I truncated the table, executed the loop with no errors, and expected that > a select count(*) > may answer 1000 ! > no. > it varies, from less than 1000 (much less, something like 900) > and more than 1000 (up to 1094) > > so... what s "volatile" in the loop ? > Everything... You are setting id1 to the result of an expression inside the loop. Everytime that statement gets executed within the loop a new random number is produced. I mean, even "id 3 date = '2000-01-01'" is repeatedly casting (I think) the string to a date and assigning it to the variable even though that statement overall is effectively immutable. David J.
