On Thu, Sep 27, 2018 at 1:18 PM Andres Freund <and...@anarazel.de> wrote: > On 2018-09-26 17:57:05 -0700, Andres Freund wrote: > > snprintf time = 1324.87 ms total, 0.000264975 ms per iteration > > pg time = 1434.57 ms total, 0.000286915 ms per iteration > > stbsp time = 552.14 ms total, 0.000110428 ms per iteration > > Reading around the interwebz lead me to look at ryu > > https://dl.acm.org/citation.cfm?id=3192369 > https://github.com/ulfjack/ryu/tree/46f4c5572121a6f1428749fe3e24132c3626c946 > > That's an algorithm that always generates the minimally sized > roundtrip-safe string output for a floating point number. That makes it > insuitable for the innards of printf, but it very well could be > interesting for e.g. float8out, especially when we currently specify a > "too high" precision to guarantee round-trip safeity.
Wow. While all the algorithms have that round trip goal, they keep doing it faster. I was once interested in their speed for a work problem, and looked into the 30 year old dragon4 and 8 year old grisu3 algorithms. It's amazing to me that we have a new algorithm in 2018 for this ancient problem, and it claims to be 3 times faster than the competition. (Hah, I see that "ryū" is Japanese for dragon. "Grisù" is a dragon from an Italian TV series.) -- Thomas Munro http://www.enterprisedb.com