From: Ryan Bradetich <rbradetich@gmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
To: Jaime Casanova <jcasanov@systemguards.com.ec>
Cc: pgsql-patches <pgsql-patches@postgresql.org>
Subject: Re: [PgFoundry] Unsigned Data Types [1 of 2]
Date: Sun, 7 Sep 2008 23:14:43 -0700
Message-ID: <e739902b0809072314s105fba05p2eca314d66f46cd6@mail.gmail.com> (raw)
In-Reply-To: <14575.1220803638@sss.pgh.pa.us>
References: <e739902b0808311335l1ad5d425r2704429c386f2f88@mail.gmail.com>
<3073cc9b0809061341q5c747488i85491e4c8e2420ba@mail.gmail.com>
<3073cc9b0809062330o62fd74dax74b1730cedc0fbb9@mail.gmail.com>
<8731.1220773267@sss.pgh.pa.us>
<3073cc9b0809070713s1df16d8dlb3be457b3584ba5c@mail.gmail.com>
<14575.1220803638@sss.pgh.pa.us>
Hello Jamie and Tom.
Thank you very much for the feedback and reviews. I will attempt to
answer all the questions I found in this thread in this one email. If I
miss any questions, let me know and I will answer it :)
Jamie: Thanks for the feedback on missing comments. I will go back
and add more comments to the code.
Jamie: Thanks for the patches. I have applied the Makefile patch to my
local tree. I am still reviewing the regressions.diffs patch. I definitely
see the issue now, I am still reviewing to see/understand if your solution
is the proper fix. I am reviewing the main PostgreSQL regression tests
to understand how the COPY is handled.
Jamie: This patch is targeted for as a PGFoundry module. I wanted it
reviewed by the PostgreSQL community for two reasons:
1. To make the data type is correct (i.e. the bugs you and Tom
identified, etc).
2. To go through the community review process so other people can
have faith/trust the module is correct.
After the community is happy with the uint data type, I will commit it to
the PGFoundry repository.
Jamie: The uint1 is an unsigned 8-bit value. It is the unsigned variant
of the "char" type. The uint8 type (which I did not provide support for in
this patch would be the unsigned variant of the int8 (64-bit type).
Jamie and Tom: Tom, you were correct. The -255::uint1 is being promoted
to the int4 data type. Here is the sample c program I used to verify this:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <postgresql/libpq-fe.h>
int main()
{
PGconn *conn;
PGresult *res;
char query[255];
conn = PQconnectdb("host=127.0.0.1 dbname=test user=rbrad");
assert(PQstatus(conn) == CONNECTION_OK);
res = PQexec(conn, "SELECT -255::uint1;");
assert(PQresultStatus(res) == PGRES_TUPLES_OK);
snprintf(query, 255, "SELECT %d::regtype", PQftype(res, 0));
PQclear(res);
res = PQexec(conn, query);
assert(PQresultStatus(res) == PGRES_TUPLES_OK);
printf("Result Type: %s\n", PQgetvalue(res, 0, 0));
PQclear(res);
PQfinish(conn);
return 0;
}
Output:
Result Type: integer
On Sun, Sep 7, 2008 at 9:07 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Ah. The scalarltsel/scalargtsel stuff has always been a bit bogus for
> cross-type comparisons; it assumes it will know both or neither of the
> two datatypes. So you can get away with using those functions for
> uint > uint (although they won't be very bright about it); but using
> them for uint > int fails outright.
> If you read the comments around that stuff it leaves quite a lot to be
> desired, but I don't really have better ideas at the moment. The best
> near-term solution for the uint module is probably not to rely on
> scalarltsel/scalargtsel for uint comparisons, but to make its own
> selectivity functions that know the uint types plus whatever standard
> types you want to have comparisons with.
Ok. Looks like I need to review these functions and develop new functions
specific for the unsigned type. I will work on this tomorrow night and
submit an updated patch.
Thanks again for the feedback and reviews!
- Ryan
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To: pgsql-patches@postgresql.org
Cc: rbradetich@gmail.com, tgl@sss.pgh.pa.us, jcasanov@systemguards.com.ec
Subject: Re: [PgFoundry] Unsigned Data Types [1 of 2]
In-Reply-To: <e739902b0809072314s105fba05p2eca314d66f46cd6@mail.gmail.com>
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