BUG #11767: ODBC driver bug when fetching constant string columns

Started by Keyur Govandeover 11 years ago3 messagesbugs
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#1Keyur Govande
keyurgovande@gmail.com

The following bug has been logged on the website:

Bug reference: 11767
Logged by: Keyur Govande
Email address: keyurgovande@gmail.com
PostgreSQL version: 9.0.3
Operating system: Centos 6.5
Description:

Hello,

This was reported to the PHP project (https://bugs.php.net/bug.php?id=68087)
but it seems like a Postgres ODBC driver bug.

If we run a SELECT statement like: SELECT id, varchar_col, date_col, 'random
string' as random;
via ODBC, then the last column comes back as junk into PHP.

In PHP we use the SQL_DESC_OCTET_LENGTH to figure out how many bytes to
allocate. But for that column, SQL_DESC_OCTET_LENGTH returns 0 and we don't
allocate enough space.

The driver issue seems to be that when SQLColAttributes() is called with
SQL_COLUMN_TYPE for column 'random', it returns SQL_VARCHAR even though the
PG type is PG_TYPE_UNKNOWN. The promotion is happening here:
http://git.postgresql.org/gitweb/?p=psqlodbc.git;a=blob;f=pgtypes.c;h=4ce7636b69d371d9f511d492c68013f070e3b32a;hb=HEAD#l665

I think the same promotion needs to happen when fetching octet-length here:
http://git.postgresql.org/gitweb/?p=psqlodbc.git;a=blob;f=pgtypes.c;h=4ce7636b69d371d9f511d492c68013f070e3b32a;hb=HEAD#l1275

Thoughts? This is not a problem when using the Vertica ODBC driver for
example.

A temporary workaround is to use a cast thusly: SELECT id, varchar_col,
date_col, varchar 'random string' as random;

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#2Michael Paquier
michael@paquier.xyz
In reply to: Keyur Govande (#1)
Re: [BUGS] BUG #11767: ODBC driver bug when fetching constant string columns

On Wed, Oct 22, 2014 at 11:22 PM, <keyurgovande@gmail.com> wrote:

The following bug has been logged on the website:

Bug reference: 11767
Logged by: Keyur Govande
Email address: keyurgovande@gmail.com
PostgreSQL version: 9.0.3

You should update to 9.0.18, you are 3.5 years of bug fixes.

If we run a SELECT statement like: SELECT id, varchar_col, date_col, 'random
string' as random;
via ODBC, then the last column comes back as junk into PHP.

In PHP we use the SQL_DESC_OCTET_LENGTH to figure out how many bytes to
allocate. But for that column, SQL_DESC_OCTET_LENGTH returns 0 and we don't
allocate enough space.

The driver issue seems to be that when SQLColAttributes() is called with
SQL_COLUMN_TYPE for column 'random', it returns SQL_VARCHAR even though the
PG type is PG_TYPE_UNKNOWN. The promotion is happening here:
http://git.postgresql.org/gitweb/?p=psqlodbc.git;a=blob;f=pgtypes.c;h=4ce7636b69d371d9f511d492c68013f070e3b32a;hb=HEAD#l665

I think the same promotion needs to happen when fetching octet-length here:
http://git.postgresql.org/gitweb/?p=psqlodbc.git;a=blob;f=pgtypes.c;h=4ce7636b69d371d9f511d492c68013f070e3b32a;hb=HEAD#l1275

Thoughts? This is not a problem when using the Vertica ODBC driver for
example.

A temporary workaround is to use a cast thusly: SELECT id, varchar_col,
date_col, varchar 'random string' as random;
This was reported to the PHP project (https://bugs.php.net/bug.php?id=68087)
but it seems like a Postgres ODBC driver bug.

pgsql-odbc is more adapted for a bug report on the ODBC driver. I am
moving the thread there.
--
Michael

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#3Keyur Govande
keyurgovande@gmail.com
In reply to: Michael Paquier (#2)
Re: [BUGS] BUG #11767: ODBC driver bug when fetching constant string columns

On Fri, Oct 24, 2014 at 9:36 AM, Michael Paquier <michael.paquier@gmail.com>
wrote:

On Wed, Oct 22, 2014 at 11:22 PM, <keyurgovande@gmail.com> wrote:

The following bug has been logged on the website:

Bug reference: 11767
Logged by: Keyur Govande
Email address: keyurgovande@gmail.com
PostgreSQL version: 9.0.3

You should update to 9.0.18, you are 3.5 years of bug fixes.

Ah I apologize, I chose the wrong version in the bug report dropdown. This
bug was observed with the latest driver: psqlodbc-09.03.0300 connecting to
a Postgres server 9.1.14.

Show quoted text

If we run a SELECT statement like: SELECT id, varchar_col, date_col,

'random

string' as random;
via ODBC, then the last column comes back as junk into PHP.

In PHP we use the SQL_DESC_OCTET_LENGTH to figure out how many bytes to
allocate. But for that column, SQL_DESC_OCTET_LENGTH returns 0 and we

don't

allocate enough space.

The driver issue seems to be that when SQLColAttributes() is called with
SQL_COLUMN_TYPE for column 'random', it returns SQL_VARCHAR even though

the

PG type is PG_TYPE_UNKNOWN. The promotion is happening here:

http://git.postgresql.org/gitweb/?p=psqlodbc.git;a=blob;f=pgtypes.c;h=4ce7636b69d371d9f511d492c68013f070e3b32a;hb=HEAD#l665

I think the same promotion needs to happen when fetching octet-length

here:

http://git.postgresql.org/gitweb/?p=psqlodbc.git;a=blob;f=pgtypes.c;h=4ce7636b69d371d9f511d492c68013f070e3b32a;hb=HEAD#l1275

Thoughts? This is not a problem when using the Vertica ODBC driver for
example.

A temporary workaround is to use a cast thusly: SELECT id, varchar_col,
date_col, varchar 'random string' as random;
This was reported to the PHP project (

https://bugs.php.net/bug.php?id=68087)

but it seems like a Postgres ODBC driver bug.

pgsql-odbc is more adapted for a bug report on the ODBC driver. I am
moving the thread there.
--
Michael