--- Israel Brewster Software Engineer Alaska Volcano Observatory Geophysical Institute - UAF 2156 Koyukuk Drive Fairbanks AK 99775-7320 Work: 907-474-5172 cell: 907-328-9145
> On Aug 10, 2020, at 8:53 AM, Stephen Frost <sfr...@snowman.net> wrote: > > Greeitngs, > > * Ron (ronljohnso...@gmail.com) wrote: >> On 8/10/20 11:38 AM, Ravi Krishna wrote: >>> Finally UUID results in write amplication in wal logs. Keep that in mind >>> if your app does lot of writes. >> >> Because UUID is 32 bytes, while SERIAL is 4 bytes? > > and because it's random and so will touch a lot more pages when you're > using it... I would point out, however, that using a V1 UUID rather than a V4 can help with this as it is sequential, not random (based on MAC address and timestamp + random). There is a trade off, of course, as with V1 if two writes occur on the same computer at the exact same millisecond, there is a very very small chance of generating conflicting UUID’s (see https://www.sohamkamani.com/blog/2016/10/05/uuid1-vs-uuid4/ <https://www.sohamkamani.com/blog/2016/10/05/uuid1-vs-uuid4/>). As there is still a random component, however, this seems quite unlikely. > > Avoid UUIDs if you can- map them to something more sensible internally > if you have to deal with them. > > Thanks, > > Stephen
