Re: Comments from a Firebird user via Borland Newsgroups.

On Wed, 2005-11-09 at 19:35 -0600, Tony Caduto wrote:
> <We found PostgreSQL a mature product, but in two things Firebird was
> simply better than PostgreSQL: Two-Phase commit (ok, that is gone with
> PG 8.1), but the second is a SNAPSHOT / REPEATABLE READ transaction
> isolation. I can't live without that when it comes having a stable view
> of data during one transaction, or did that change with 8.1? Is there
> now a SNAPHOST / REPEATBLE READ transaction isolation level available as
> well?>
>
> Just wondering what the PG take on this snapshot repeatable read stuff is.

It has kinda been there for years and is what PostgreSQL uses to achieve
a consistent snapshot with pg_dump. Of course, per spec the DB is
allowed to upgrade the isolation level to SERIALIZABLE from what you
specify you require as a minimum (REPEATABLE READ in this case).

session1:
begin isolation level repeatable read;

session2:
insert into junk values (1);

session1:
rbt=# select * from junk;
col
-----
1
(1 row)

session2:
insert into junk values (2);

session1:
rbt=# select * from junk;
col
-----
1
(1 row)

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