From: | Alex Goncharov <alex-goncharov(at)comcast(dot)net> |
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To: | pgsql-hackers(at)postgresql(dot)org |
Subject: | Re: libpq, PQdescribePrepared -> PQftype, PQfmod, no PQnullable |
Date: | 2011-10-07 00:46:47 |
Message-ID: | E1RByaN-000DPv-M4@hanssachs.home |
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Lists: | pgsql-hackers |
,--- You/Andres (Fri, 7 Oct 2011 02:28:30 +0200) ----*
| > a lot of cases where the database could deduce (quite easily) that a
| > result column cannot be null
| Could you quickly explain what exactly you want that information for? Just
| because it has been done before doesn't necessarily mean its a good idea...
I am not writing a database application here (i.e. I am not storing
the data). I am responding to a client requirement, basically:
Given a SELECT (or possibly, simpler, a table name), tell me which
columns are non-nullable?
I can give the answer about the tables trivially in 'psql' (using
pg_attribute.attnotnull). But it has to be done inside the C code I
wrote a couple of years ago, already using libpq, preparing and
describing arbitrary statements... If I could get the required
information through some use of PQ* functions...
But, oh well, I'll "PQexec(a-fancy-select-from-pg_attribute)".
Ugly :(
-- Alex -- alex-goncharov(at)comcast(dot)net --
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