Thread: Use of Serial type

        Using php, I create a table with a SERIAL field. In the same
script, the last thing I do is a COPY ... FROM ... USING DELIMITERS...to
load data I have outputted from another system into a text delimited
file.  I didn't get the autoincrementing of the serial field to work, so
I modified my output-from-another-system program to "manually" set the
serial field value.  That worked.  However, it does not seem to have
done a default SETVAL.  Do I do a "manual" SETVAL of 1 greater than the
highest value from the input text file, or am I missing something in the
create and copy process?

Jim Beckstrom

on 9/18/02 12:44 PM, jrbeckstrom@voyager.net purportedly said:

> Using php, I create a table with a SERIAL field. In the same
> script, the last thing I do is a COPY ... FROM ... USING DELIMITERS...to
> load data I have outputted from another system into a text delimited
> file.  I didn't get the autoincrementing of the serial field to work, so
> I modified my output-from-another-system program to "manually" set the
> serial field value.  That worked.  However, it does not seem to have
> done a default SETVAL.  Do I do a "manual" SETVAL of 1 greater than the
> highest value from the input text file, or am I missing something in the
> create and copy process?

I am not certain about the behavior of COPY, but with an INSERT the serial
trigger will not click if you are inserting a value into the serial field.
Nor will it be updated. This behavior may have changed since I last
experienced it, but that's my recollection. This may be the same for COPY.
So you probably have to manually update the serial counter.

Keary Suska
Esoteritech, Inc.
"Leveraging Open Source for a better Internet"

2002. szeptember 18. 20:44 dátummal Jim Beckstrom ezt írta:
|         Using php, I create a table with a SERIAL field. In the same
| script, the last thing I do is a COPY ... FROM ... USING
| DELIMITERS...to load data I have outputted from another system into a
| text delimited file.  I didn't get the autoincrementing of the serial
| field to work, so I modified my output-from-another-system program to
| "manually" set the serial field value.  That worked.  However, it
| does not seem to have done a default SETVAL.  Do I do a "manual"
| SETVAL of 1 greater than the highest value from the input text file,
| or am I missing something in the create and copy process?
|
| Jim Beckstrom

COPY is just a SQL-like shorthand for dumping and restoring database
tables, so it's not the convenient way to insert data as regular with
autoincrementing columns of type serial.

You should also consider about what would happen in concurrent usage if
you merely use "max+1". It may be better to use
setval('seq', currval('seq')+1);

But, AFAIR, Tom Lane wrote me that this solution can be also crashed in
concurrent usage. If you're interested in, please, search the
pgsql-general archives.


--
Papp, Győző
- pgerzson@freestart.hu

Jim,

>         Using php, I create a table with a SERIAL field. In the same
> script, the last thing I do is a COPY ... FROM ... USING DELIMITERS...to
> load data I have outputted from another system into a text delimited
> file.  I didn't get the autoincrementing of the serial field to work, so
> I modified my output-from-another-system program to "manually" set the
> serial field value.  That worked.  However, it does not seem to have
> done a default SETVAL.  Do I do a "manual" SETVAL of 1 greater than the
> highest value from the input text file, or am I missing something in the
> create and copy process?

That sounds fine.  However, I would bundle everything in a transaction to be
safe.  Otherwise, you risk having a user access the table without the serial
value correctly set.

--
-Josh Berkus
 Aglio Database Solutions
 San Francisco