On Mon, Feb 19, 2024 at 03:08:45PM +0100, Laurenz Albe wrote: > On Sat, 2024-02-17 at 12:24 -0800, Andres Freund wrote: >> I wonder if we should move the core part for converting to hex to numutils.c, >> we already have code the for the inverse. There does seem to be further >> optimization potential in the conversion, and that seems better done >> somewhere >> central rather than one type's output function. OTOH, it might not be worth >> it, given the need to add the dashes. > > I thought about it, but then decided not to do that. > Calling a function that converts the bytes to hex and then adding the > hyphens will slow down processing, and I think the code savings would be > minimal at best.
Yeah, I'm not sure either if that's worth doing, the current conversion code is simple enough. I'd be curious to hear about ideas to optimize that more locally, though. I was curious about the UUID one, and COPYing out 10M rows with a single UUID attribute brings down the runtime of a COPY from 3.8s to 2.3s here on a simple benchmark, with uuid_out showing up at the top of profiles easily on HEAD. Some references for HEAD: 31.63% 5300 postgres postgres [.] uuid_out 19.79% 3316 postgres postgres [.] appendStringInfoChar 11.27% 1887 postgres postgres [.] CopyAttributeOutText 6.36% 1065 postgres postgres [.] pgstat_progress_update_param And with the patch for uuid_out: 22.66% 2147 postgres postgres [.] CopyAttributeOutText 12.99% 1231 postgres postgres [.] uuid_out 11.41% 1081 postgres postgres [.] pgstat_progress_update_param 4.79% 454 postgres postgres [.] CopyOneRowTo That's very good, so I'd like to apply this part. Let me know if there are any objections. -- Michael
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