Re: Fastest memmove in C

FarjadFarid(ChkNet) wrote:

> Excellent research and could be well worth checking out. As it could
> improve the performance of postgresql engine.

0) We certainly do a lot of memory copying.

1) this work is under the "Code Project Open License" which doesn't look
compatible with our Postgres license on first blush. Maybe T Herselman
would agree to share under the Postgres licence, which would make things
easier.

2) from the description, the code is probably tailored to specific
compilers. Even if it's faster now in some mainstream compilers, it
won't be in yesterday or tomorrow's ones. Also, there are probably
going to be variations depending on CPU features.

3) How much faster does Postgres get when you replace memcpy/memmove
with these Apex versions? If the percentage to be gained is small, then
there's probably no point in spending a lot of effort into providing
platform-specific implementations of these things anyway.

If you have enough interest in this topic, you could try using these
Apex versions in Postgres and measuring an improvement, to get a
discussion going.

--
Álvaro Herrera http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services