Re: Nasty, propagating POLA violation in COPY CSV HEADER

On Wed, Jun 20, 2012 at 12:18:45PM -0400, Tom Lane wrote:
> David Fetter <david(at)fetter(dot)org> writes:
> > OK, new proposal:
>
> > COPY FROM (Thanks, Andrew! Must not post while asleep...) should have
> > an option which requires that HEADER be enabled and mandates that the
> > column names in the header match the columns coming in.
>
> > Has someone got a better name for this option than
> > KEEP_HEADER_COLUMN_NAMES?
>
> Well, if it's just checking that the list matches, then maybe
> CHECK_HEADER would do.

OK

> In your original proposal, I was rather wondering what should happen
> if the incoming file didn't have the same set of columns called out
> in the COPY command's column list. (That is, while *rearranging*
> the columns might be thought non-astonishing, I'm less convinced
> about a copy operation that inserts or defaults columns differently
> from what the command said should happen.) If we're just checking
> for a match, that question goes away.

Let's imagine we have a table foo(id serial, t text, n numeric) and a
CSV file foo.csv with headers (n, t). Just to emphasize, the column
ordering is different in the places where they match.

Would

COPY foo (t,n) FROM '/path/to/foo.csv' WITH (CSV, HEADER, CHECK_HEADER)

now "just work" (possibly with some performance penalty) and

COPY foo (t,n) FROM '/path/to/foo.csv' WITH (CSV, HEADER)

only "work," i.e. import gobbledygook, in the case where every t entry
in foo.csv happened to be castable to NUMERIC?

Cheers,
David.
--
David Fetter <david(at)fetter(dot)org> http://fetter.org/
Phone: +1 415 235 3778 AIM: dfetter666 Yahoo!: dfetter
Skype: davidfetter XMPP: david(dot)fetter(at)gmail(dot)com
iCal: webcal://www.tripit.com/feed/ical/people/david74/tripit.ics

Remember to vote!
Consider donating to Postgres: http://www.postgresql.org/about/donate