From: | Uday Bhaskar V <uday(dot)bhaskar579(at)gmail(dot)com> |
---|---|
To: | tomas(dot)vondra(at)2ndquadrant(dot)com |
Cc: | pgsql-hackers(at)postgresql(dot)org |
Subject: | Re: Sequential UUID Generation |
Date: | 2018-10-30 13:22:15 |
Message-ID: | CAFowjW2QcUx-xhEXTMi=6QbeBCNjjttYzVyunv+Tv7s9PmE=hA@mail.gmail.com |
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Lists: | pgsql-hackers |
Thanks Tomas! I will try.
Regards,
Uday
On Tue, Oct 30, 2018 at 6:43 PM Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>
wrote:
> I don't think PostgreSQL has anything like that at the moment. It would
> not be difficult to tweak the UUID generator to generate sequential (or
> monotonic) values, the tricky part seems to be durability requirements.
>
> One idea would be to simply store the value in (shared) memory, but that
> would mean losing the state on restart/crash, so there would need to be
> some sort of protection against generating duplicate values (say, using
> postmaster timestamp as the first 64 bits of the UUID).
>
> Another idea is to piggy-back this on bigint sequence somehow - split
> the 128bit range into 64+64, use the sequence value for the first 64b
> and pick the other half by random. That would guarantee both uniqueness,
> monotonicity and durability. And it would also be fairly random, making
> it difficult to guess UUIDs.
>
> regards
>
> On 10/29/2018 04:06 PM, Uday Bhaskar V wrote:
> > Hi,
> >
> > We have migrated from Oracle to Postgres, there because of the
> > replication requirements we used UUID columns.
> > I did a POC(in postgres) with sequential UUID against Non sequential
> > which has shown lot of different in space utilization and index size.
> > Sql server has "newsequentialid" which generates sequential UUID. I
> > need similar functionality here.
> > I want to create a function which generates a sequential UUIDs, Any
> > suggestions or support would be much appreciated.
> >
> > Thanks,
> > Uday
>
> --
> Tomas Vondra http://www.2ndQuadrant.com
> PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
>
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