On 4/14/20 3:19 PM, David Steele wrote: > On 4/14/20 3:03 PM, Andrew Dunstan wrote: >> >> On 4/14/20 1:33 PM, David Steele wrote: >>> On 4/14/20 1:27 PM, Alvaro Herrera wrote: >>>> On 2020-Apr-14, David Steele wrote: >>>> >>>>> On 4/14/20 12:56 PM, Robert Haas wrote: >>>>> >>>>>> Hmm, did David suggest that before? I don't recall for sure. I think >>>>>> he had some suggestion, but I'm not sure if it was the same one. >>>>> >>>>> "I'm also partial to using epoch time in the manifest because it is >>>>> generally easier for programs to work with. But, human-readable >>>>> doesn't >>>>> suck, either." >>>> >>>> Ugh. If you go down that road, why write human-readable contents at >>>> all? You may as well just use a binary format. But that's a very >>>> slippery slope and you won't like to be in the bottom -- I don't see >>>> what that gains you. It's not like it's a lot of work to parse a >>>> timestamp in a non-internationalized well-defined human-readable >>>> format. >>> >>> Well, times are a special case because they are so easy to mess up. >>> Try converting ISO-8601 to epoch time using the standard C functions >>> on a system where TZ != UTC. Fun times. >> >> Even if it's a zulu time? That would be pretty damn sad. > ZULU/GMT/UTC are all fine. But if the server timezone is EDT for > example (not that I recommend this) you are likely to get the wrong > result. Results vary based on your platform. For instance, we found > MacOS was more likely to work the way you would expect and Linux was > hopeless. > > There are all kinds of fun tricks to get around this (sort of). One is > to temporarily set TZ=UTC which sucks if an error happens before it > gets set back. There are some hacks to try to determine your offset > which have inherent race conditions around DST changes. > > After some experimentation we just used the Posix definition for epoch > time and used that to do our conversions: > > https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap04.html#tag_04_16 > > >
OK, but I think if we're putting a timestamp string in ISO-8601 format in the manifest it should be in UTC / Zulu time, precisely to avoid these issues. If that's too much trouble then yes an epoch time will probably do. cheers andrew -- Andrew Dunstan https://www.2ndQuadrant.com PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
