On 12-06-22 11:36 AM, Tom Lane wrote:
"D'Arcy Cain"<da...@druid.net> writes: The thing is that either of those approaches is hugely more expensive than just providing a second C function. It costs probably thousands of cycles to inline that SQL function, each time it's used in a query.
I assumed itwould be more expensive but didn't know it would be that much more.
I doubt that an "auto reverse the arguments" facility would be very much cheaper. You could maybe argue that the aggregated maintenance and space costs of all the commutator-pair functions are enough to justify having some such solution instead, but I'm doubtful --- and even if true, getting from here to there would be painful.
And it would only apply to a very specific type of function. The other idea I had was to just have the second C function call the first but that didn't work. Here is what I tried. PG_FUNCTION_INFO_V1(chkpass_eq); Datum chkpass_eq(PG_FUNCTION_ARGS) { chkpass *a1 = (chkpass *) PG_GETARG_POINTER(0); text *a2 = (text *) PG_GETARG_TEXT_P(1); char str[9]; strlcpy(str, a2->vl_dat, sizeof(str)); PG_RETURN_BOOL(strcmp(a1->password, crypt(str, a1->password)) == 0); } PG_FUNCTION_INFO_V1(chkpass_eq2); Datum chkpass_eq2(PG_FUNCTION_ARGS) { return chkpass_eq(PG_GETARG_POINTER(1), PG_GETARG_TEXT_P(0)); } Now in this specific case the function is trivial and writing it twice is no big deal but in general I hate writing the same code twice. I suppose I could extract the actual operation out to a third function and call it from the others. I may do that anyway just for the value of the example. Or is there a way to do what I tried above? -- D'Arcy J.M. Cain <da...@druid.net> | Democracy is three wolves http://www.druid.net/darcy/ | and a sheep voting on +1 416 425 1212 (DoD#0082) (eNTP) | what's for dinner. IM: da...@vex.net -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers