Обсуждение: query column def

Hi;

I am reverse engineering a PostgreSQL database by querying catalog
tables. I have run into a problem where I can not determine the exact
info used in i.e. the CREATE TABLE statement. For example; how to
determine the exact precision/length and scale used in a NUMERIC(p,s)
column def.

Looking at the PostgreSQL ODBC driver I see that it does some funky
stuff such as reporting VARCHAR(maxlen) instead of i.e. VARCHAR(50) or
whatever the column def was. So it appears that the author had similar
problems. The result is that the ODBC driver does not appear to be
absolutely accurate.

Is this information availible somewhere in the catalog tables?

Peter

Peter Harvey <pharvey@codebydesign.com> writes:
> Is this information availible somewhere in the catalog tables?

Yes, in the atttypmod column of pg_attribute.

I'd recommend looking at psql's \d commands (describe.c), or at
pg_dump, to see the approved way to retrieve catalog info.  Those
are kept up to date pretty faithfully, whereas other interfaces
aren't necessarily.  (Feel free to submit a patch to fix ODBC...)
        regards, tom lane