Jeff Janes <jeff.ja...@gmail.com> writes: > I saw that the hotspot was pq_begintypsend at 20%, which was twice the > percentage as the next place winner (AllocSetAlloc).
Weird. > Why is this such a bottleneck? Not sure, but it seems like a pretty dumb way to push the stringinfo's len forward. We're reading/updating the len word in each line, and if your perf measurements are to be believed, it's the re-fetches of the len values that are bottlenecked --- maybe your CPU isn't too bright about that? The bytes of the string value are getting written twice too, thanks to uselessly setting up a terminating nul each time. I'd be inclined to replace the appendStringInfoCharMacro calls with appendStringInfoSpaces(buf, 4) --- I don't think we care exactly what is inserted into those bytes at this point. And maybe appendStringInfoSpaces could stand some micro-optimization, too. Use a memset and a single len adjustment, perhaps? regards, tom lane