From: Sabin Coanda <sabin.coanda@deuromedia.ro>
To: pgsql-sql@postgresql.org
Subject: Re: system table storing sequence attributes
Date: Tue, 22 May 2007 16:12:06 +0300
Message-ID: <f2uq6o$112t$1@news.hub.org> (raw)
References: <f2u4jn$a03$1@news.hub.org>
<pan.2007.05.22.07.43.23.678145@gmail.com>
<f2unc1$kdo$1@news.hub.org>
<pan.2007.05.22.12.41.38.862364@gmail.com>
""Marcin Stêpnicki"" <mstepnicki@gmail.com> wrote in message
news:pan.2007.05.22.12.41.38.862364@gmail.com...
...
>
> I think that you either misunderstood this statement or try to break your
> application in a nasty way ;). Please tell us more about your problem
> and/or what do you want to achive, because sequences behave this way for a
> reason (concurrency issues). Perhaps there is another solution.
I have a table with a serial primary key aoto generated by a sequence. I
add/remove records. At a moment I'd like to know what is the current value
of the sequence. I don't wish to know this in the same session where I
add/remove records.
My Postgresql version is "PostgreSQL 8.2.3 on i686-pc-mingw32, compiled by
GCC gcc.exe (GCC) 3.4.2 (mingw-special)", on Windows XP OS, and I use
pgAdmin to open sessions on my database.
With this environment, try the following scenario:
Make a demo table:
CREATE TABLE "tbFoo"
(
"ID" integer NOT NULL DEFAULT nextval('"tbFoo_ID_seq"'::regclass)
)
At the beginning, no record are inserted in the table. I call:
SELECT currval( pg_get_serial_sequence('"tbFoo"','ID') );
This rise the following error: ERROR: currval of sequence "tbFoo_ID_seq" is
not yet defined in this session
SQL state: 55000
Then I add a record there:
INSERT INTO "tbFoo" DEFAULT VALUES;
I call SELECT currval( pg_get_serial_sequence('"tbFoo"','ID') ), and I get
1. That's ok because I just use indirectly a nextval to that sequence in the
insert process, on this session.
I close the session, and I open another one.
I call SELECT currval( pg_get_serial_sequence('"tbFoo"','ID') ), and I get
the error again:
ERROR: currval of sequence "tbFoo_ID_seq" is not yet defined in this session
SQL state: 55000
Sabin
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To: pgsql-sql@postgresql.org
Cc: sabin.coanda@deuromedia.ro
Subject: Re: system table storing sequence attributes
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