Re: UUID or auto-increment

[Israel Brewster <ijbrewster@xxxxxxxxxx>]

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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 <sfrost@xxxxxxxxxxx> wrote:

Greeitngs,

* Ron (ronljohnsonjr@xxxxxxxxx) 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/). 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