Re: UUID with variable length - Mailing list pgsql-general

From Alvaro Herrera
Subject Re: UUID with variable length
Date
Msg-id 20201016160932.GA32253@alvherre.pgsql
Whole thread Raw
In response to UUID with variable length  (Dirk Krautschick <Dirk.Krautschick@trivadis.com>)
List pgsql-general
On 2020-Oct-15, Dirk Krautschick wrote:

> Hi,
> 
> I have here a situation with the usage of UUID. Here the database user
> allows UUIDs with less then 16 byte lengths (please don't ask :-) ).
> 
> Of course there are some technical ways to do the filling of the not
> used bytes but I hope there is a better solution. This UUID is used as
> primary Key and for indexing.

How much shorter than 16 bytes are you expecting your UUIDs to be?  If
they're not short enough, you'll still have to store a lot of padding
space, and considering that you'll need a length indicator if you use
variable length, it does not really sound like you'll save much actual
space.  And you'll definitely be getting a slower datatype, since doing
operations will become more complex.

If this were me, I would see about zeroing out the unused bytes and not
waste a lot of developer time on this.



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