> Thank you, fmgr_info() looks like the best place to do the parallel safety > check. > Having a quick look at its callers, I didn't find any concerning place (of > course, > we can't be relieved until the regression test succeeds.) Also, with > fmgr_info(), > we don't have to find other places to add the check to deal with functions > calls > in execExpr.c and execExprInterp.c. This is beautiful. > > But the current fmgr_info() does not check the parallel safety of builtin > functions. It does not have information to do that. There are two options. > Which do you think is better? I think 2. > > 1) fmgr_info() reads pg_proc like for non-builtin functions This ruins the > effort > for the fast path for builtin functions. I can't imagine how large the > adverse > impact on performance would be, but I'm worried.
For approach 1): I think it could result in infinite recursion. For example: If we first access one built-in function A which have not been cached, it need access the pg_proc, When accessing the pg_proc, it internally still need some built-in function B to scan. At this time, if B is not cached , it still need to fetch function B's parallel flag by accessing the pg_proc.proparallel. Then it could result in infinite recursion. So, I think we can consider the approach 2) Best regards, houzj
