Re: [INTERFACES] Postgresql + lo - Mailing list pgsql-interfaces

From Tom Lane
Subject Re: [INTERFACES] Postgresql + lo
Date
Msg-id 14398.932738250@sss.pgh.pa.us
Whole thread Raw
In response to Postgresql + lo  (Florian Baumert <baumert@plt.de>)
List pgsql-interfaces
Florian Baumert <baumert@plt.de> writes:
> What happens is that it writes a -1 to the screen and a database-error
> "ERROR: lo_lseek: invalid large obj descriptor (0)"

You need "begin transaction"/"end transaction" around the use of the
LO handle (ie, surrounding lo_open ... lo_close).

The documentation has always stated that lo_open must be wrapped in
a transaction, but Postgres versions before 6.5 didn't enforce that
rule.  (Instead, they'd just fail occasionally if you broke it :-(.)

6.5 enforces the rule by auto-closing LO handles at transaction
commit --- which will be instantly upon completion of the lo_open
command, if you are not inside a transaction; so the first attempt
to do anything with the handle will draw "invalid large obj
descriptor".

This is definitely getting to be a FAQ...
        regards, tom lane


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