Hi
> -----Original Message-----
> From: pgsql-general-owner@postgresql.org [mailto:pgsql-general-owner@postgresql.org] On Behalf Of Kevin Golding
> Sent: Donnerstag, 24. August 2017 07:08
> To: pgsql-general@postgresql.org
> Subject: [GENERAL] 'value too long' and before insert/update trigger
>
> Hi all
> I'm currently migrating a legacy Informix 4gl application to run on PostgreSQL (v9.5.8)
>
> There are errors occurring because sometimes the application tries to insert/update values longer than the
> definition of the database column.
> The error message is eg. "value too long for type character(20)".
>
> The behaviour under Informix is to silently truncate the saved value, but with PostgreSQL it crashes our application
> program. Obviously the short answer is to modify the application so that it does not attempt to save values that are
> too long, but with 1000+ programs and approx. 8000 insert/update statements to review this will take a lot of time.
If there is no good reason to force the length of the field to be a maximum of 20 characters, you may change the data
typeto text.
> I was hoping to emulate the Informix behaviour by creating triggers to run before each insert/update that would
> check the length of the values being saved and truncate if too long. However I'm still getting the error messages.
> Presumably the length validation is being done before the trigger is run. Is there some way this could be changed so
> the trigger happens first?
When you create the trigger you can define if the function must be called before or after the action.
Something like:
CREATE TRIGGER name
BEFORE INSERT OR UPDATE ON table_name
FOR EACH ROW EXECUTE PROCEDURE ...;
In the function you must then replace the value of the string before you return the NEW record to the calling process:
[...]
NEW.variable_name := substr(NEW.variable_name,1,20);
[...]
RETURN NEW;
Hope this helps.
Bye
Charles
> I've seen examples that involve changing the char type columns to text, but this changes the semantics of string
> comparisons with regard to trailing spaces, and I'm concerned that this might cause subtle and hard to find problems
> within the application.
>
> Thanks
> Kevin
>
>
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