On Tue, Oct 21, 2014 at 10:16 AM, Tom Lane t...@sss.pgh.pa.us wrote:
(Of course, I'm not for the feature w.r.t. SQL either. But breaking data
compatibility is just adding an entire new dimension of trouble.
Another dimension of the trouble is breaking the operation of the
tools that parse
,--- You/Peter (Tue, 10 Jan 2012 19:13:42 +0200) *
| On tis, 2011-12-13 at 07:55 -0500, Alex Goncharov wrote:
|char *PQcmdStatus(PGresult *res);
|char *PQcmdTuples(PGresult *res);
|
| Unreasonable:
|
|a. What, these two can modify 'res' I pass in?..
|
|b. Oh, yes
Compare:
int PQntuples(const PGresult *res)
Reasonable: doesn't modify 'res'.
With:
char *PQcmdStatus(PGresult *res);
char *PQcmdTuples(PGresult *res);
Unreasonable:
a. What, these two can modify 'res' I pass in?..
b. Oh, yes, because they return 'char *' pointing to
,--- I/Alex (Tue, 13 Dec 2011 07:55:45 -0500) *
| If the above change causes a warning in a client code, so much the
| better: the client code is doing something unreasonable like the *s
| assignment in my example above.
,--- Robert Haas (Tue, 13 Dec 2011 10:51:54 -0500) *
| Or they just
Thank you all who replied!
-- Alex -- alex-goncha...@comcast.net --
/*
* They're only trying to make me LOOK paranoid!
*/
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[ Thanks all for the very productive discussion in the thread
libpq, PQdescribePrepared - PQftype, PQfmod, no PQnullable
which I originated. Very useful. Now on something different. ]
About two years ago, I had to research some PostgreSQL failures on
HP-UX on a lame PA-RISC box. Looking
Thanks...
,--- You/Tom (Sun, 09 Oct 2011 22:29:19 -0400) *
| Well, HP hasn't exactly been forthcoming with support on their own end,
| but we do have an HPUX 11.31 IA64 machine in the buildfarm,
Should I read the above as:
1. The PostgreSQL server will build on HPUX 11.31 IA64.
2. The
The obvious typos:
,--- I/Alex (Thu, 06 Oct 2011 19:42:13 -0400) *
| (may use pg_attribute.attnotnull on t1, t2, is I didn't see the 'create's.
(may use pg_attribute.attnotnull on t1, t2, if I didn't see the 'create's.
| Now, for this statement, I can easily identify non-nullable
,--- Peter Eisentraut (Fri, 07 Oct 2011 11:14:09 +0300) *
| On tor, 2011-10-06 at 20:15 -0400, Alex Goncharov wrote:
| P.S. And on the odd chance that somebody thinks that this
| functionality would be possible and helpful to add to libpq, and
| the problem is in the lack of human
,--- You/Merlin (Fri, 7 Oct 2011 07:39:57 -0500) *
| On Thu, Oct 6, 2011 at 5:02 PM, Alex Goncharov
| ,--- Merlin Moncure (Thu, 6 Oct 2011 16:28:56 -0500) *
| | hm, good point. not sure how it's useful though. I suppose an
| | application could leverage that for validation purposes
My understanding is that libpq does not allow one to find if a result
set column is nullable.
Is this right?
(I know how to get a table column nullability information from
pg_attribute.attnotnull, but when coding around the libpq API:
* Is, OMG, ugly.
* Doesn't cover the arbitrary SELECT
,--- I/Alex (Thu, 06 Oct 2011 14:02:14 -0400) *
| My understanding is that libpq does not allow one to find if a result
| set column is nullable.
,--- You/Merlin (Thu, 6 Oct 2011 15:16:18 -0500) *
| why aren't you using PQgetisnull()?
This function is not about the nullability of a column
,--- I/Alex (Thu, 06 Oct 2011 14:02:14 -0400) *
| My understanding is that libpq does not allow one to find if a result
| set column is nullable.
,--- You/Merlin (Thu, 6 Oct 2011 15:16:18 -0500) *
| why aren't you using PQgetisnull()?
,--- I/Alex (Thu, 06 Oct 2011 16:22:28 -0400) *
|
,--- You/Florian (Fri, 7 Oct 2011 01:00:40 +0200) *
| On Oct7, 2011, at 00:02 , Alex Goncharov wrote:
| ,--- Florian Pflug (Thu, 6 Oct 2011 23:16:53 +0200) *
| | Sure, but there are still a lot of cases where the database could deduce
| | (quite easily) that a result column cannot
,--- You/Bruce (Thu, 6 Oct 2011 19:09:16 -0400 (EDT)) *
| (Look, I appreciate anybody's reply and readiness to help, but if you
| have a limited expertise in the subject area, why bother replying?)
|
| FYI, I see 867 Postgres posts mentioning Merlin Moncure in the past
| year:
|
|
The obvious typos (sorry if this is a duplicate message, I sent the
first one from a wrong address):
,--- I/Alex (Thu, 06 Oct 2011 19:42:13 -0400) *
| (may use pg_attribute.attnotnull on t1, t2, is I didn't see the 'create's.
(may use pg_attribute.attnotnull on t1, t2, if I didn't see
,--- 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
,--- You/anara...@anarazel.de (Fri, 07 Oct 2011 02:54:39 +0200) *
|
| Given a SELECT (or possibly, simpler, a table name), tell me which
| columns are non-nullable?
| That doesnt explain why it's needed.
It's needed for some meta analysis. That's as much as I can say.
| To get
,--- You/Florian (Fri, 7 Oct 2011 03:21:23 +0200) *
| Sure. Deducing nullability isn't a hard problem, at least not if it's
| OK to simply say nullable if things get too complex.
Yes.
| And in PostgreSQL, this could be done by combining
|
| (1) Oid PQftable(const PGresult *res, int
,--- I/Alex (Mon, 24 May 2010 12:25:18 -0400) *
| No equivalent of FETCH_COUNT is available at the libpq level, so I
| assume that the interface I am using is smart enough not to send
| gigabytes of data to FE.
|
| Where does the result set (GBs of data) reside after I call
| PQexecPrepared?
,--- Abhijit Menon-Sen (Tue, 25 May 2010 17:26:18 +0530) *
| Unless you explicitly declare and fetch from an SQL-level cursor, your
| many GBs of data are going to be transmitted to libpq, which will eat
| lots of memory. (The wire protocol does have something like cursors,
| but libpq does
I have some libpq-using application code, in which fetching the data
follows this logic (after a statement has been prepared):
PQexecPrepared(pg_result, pg_conn, pg_statement_name, input_param_cnt,
param_values, param_lengths,
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