On Wed, Dec 24, 2025 at 9:08 AM KAZAR Ayoub <[email protected]> wrote:
> Hello, > Following the same path of optimizing COPY FROM using SIMD, i found that > COPY TO can also benefit from this. > > I attached a small patch that uses SIMD to skip data and advance as far as > the first special character is found, then fallback to scalar processing > for that character and re-enter the SIMD path again... > There's two ways to do this: > 1) Essentially we do SIMD until we find a special character, then continue > scalar path without re-entering SIMD again. > - This gives from 10% to 30% speedups depending on the weight of special > characters in the attribute, we don't lose anything here since it advances > with SIMD until it can't (using the previous scripts: 1/3, 2/3 specials > chars). > > 2) Do SIMD path, then use scalar path when we hit a special character, > keep re-entering the SIMD path each time. > - This is equivalent to the COPY FROM story, we'll need to find the same > heuristic to use for both COPY FROM/TO to reduce the regressions (same > regressions: around from 20% to 30% with 1/3, 2/3 specials chars). > > Something else to note is that the scalar path for COPY TO isn't as heavy > as the state machine in COPY FROM. > > So if we find the sweet spot for the heuristic, doing the same for COPY TO > will be trivial and always beneficial. > Attached is 0004 which is option 1 (SIMD without re-entering), 0005 is the > second one. > > > Regards, > Ayoub > Hello, Nazir and Ayoub! Nazir, sorry for the late reply, I am on holiday. :-) I wanted to thank you for the tips on using cpupower to get less variance in my test results. Ayoub, I suppose it was inevitable the SIMD patch would work for copying out as well as copying in! I am back at work on 5 Jan 2026, so I till try to carve out time to test this then, using Nazir's tips. Happy Holidays! -Manni -- -- Manni Wood EDB: https://www.enterprisedb.com
