Re: Sequences in transaction context

"Erik Pearson" <erik(at)cariboulake(dot)com> writes:

> Thanks for the reply! I'm afraid I didn't test this thoroughly. I noticed
> that nextval changed the sequence for all transactions, and assumed that
> currval simply translated to the (nextval() - 1), which it does not, as I
> now understand it. I was also unclear on the FAQ -- I guess I thought that
> "race condition" referred to concurrent access to the underlying store,
> either delivering duplicate values or something.
>
> One last followup question -- what's MVCC?

Multi-Version Concurrency Control. See:

http://postgresql.crimelabs.net/users-lounge/docs/7.1/postgres/mvcc.html

The currval/nextval stuff actually isn't strict MVCC (since it doesn't
require that the usages be inside a transaction) but it's the same
concept.

-Doug
--
The rain man gave me two cures; he said jump right in,
The first was Texas medicine--the second was just railroad gin,
And like a fool I mixed them, and it strangled up my mind,
Now people just get uglier, and I got no sense of time... --Dylan