Row versioning

[Ruediger Herrmann]

Hi all,

has anyone implemented row versions/timestamps in PostgreSQL or any
thoughts on this?
Did I hit the right term? What I want to achieve is optimistic
concurrency beyound transaction boundaries. When retrieving data
I would also retrieve the row version and later on, in a different
transaction, before updating the data, I could check if was unchanged.
(row version at read time = row version at update time)

What are the pro's and con's about adding a "sequence" row that is
incremented by a trigger each time the row is updated?
Is having a timestamp row instand better?

Regards
Ruediger


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[Tom Lane]

Re: Row versioning

"Ruediger Herrmann" <ruediger.herrm ann@gmx.de> writes:[color=blue]
> has anyone implemented row versions/timestamps in PostgreSQL or any
> thoughts on this?
> Did I hit the right term? What I want to achieve is optimistic
> concurrency beyound transaction boundaries. When retrieving data
> I would also retrieve the row version and later on, in a different
> transaction, before updating the data, I could check if was unchanged.[/color]

You could use the xmin system column for this.

regards, tom lane

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