On Fri, Sep 26, 2025 at 11:37 AM Tom Lane <[email protected]> wrote: > Richard Guo <[email protected]> writes: > > FWIW, I'm a bit concerned about the double for loop inside > > choose_plan_name(), especially since the outer loop runs with a true > > condition. Maybe I'm just worrying over nothing, as we probably don't > > expect a large number of subroots in practice, but the nested loops > > still make me a little uneasy.
> I really doubt that a query could have enough subplans to make > that a problem. But if I'm wrong, it's surely something we could > improve in a localized way later. I'm concerned not only about the potential for a large number of subplans but also because if there happens to be a bug within the nested loops, the always-true condition in the outer loop could cause an infinite loop. However, if you're confident that the code inside the loop is completely bug-free and will remain so through future changes, then this shouldn't be an issue. Looking at choose_plan_name(), IIUC, the nested loop is used to find the next unused suffix number for a given name. I'm wondering why not simply iterate through glob->subplanNames once, check the suffix number for each name matching the given base name, determine the current maximum suffix, and then use "max_suffix + 1" as the next unused suffix. This approach requires only a single pass through the list, and if there's a bug, the worst-case scenario would be a duplicate name rather than an infinite loop. It seems to me that this approach is both more efficient and less risky. - Richard
