From: Keith Millard <Kmillard@pumatech.com>
To: 'pgsql-interfaces@postgresql.org' <pgsql-interfaces@postgresql.org>
Subject: Postgres odbc driver bug
Date: Tue, 1 May 2001 06:36:36 -0700
Message-ID: <D7058849BACBD411B0E900508BFDF7DA4BFE2A@MAILNH01> (raw)
We have found a reproducible problem with the Postgres ODBC driver. It has
to do with the parameter replacement feature in the driver. Below is a
piece of test code that shows the problem. We were able to fix the problem
by making a change to execute.c in the ODBC driver code (attached).
odbc driver version : Found in both 6.50 and 7.01.0004.
postgresql database version : Found with both 7.0.2 and 7.0.3 versions of
Postgres.
Server Operating System: Windows2000
Client Operation System: Windows2000
Explanation of the odbc driver bug:
/*****************************************
* ERROR HAPPENS HERE:
* If we set the buffer that we binded to column "text1" now, it will
FAIL.
* The SQLExecute in doQuery() will succeed (finding 0 rows), and the
* SQLFetchScroll call will return SQL_NO_DATA_FOUND.
*
* This is because of a bug in the odbc driver. The call to
SQLNumResultCols
* will execute the query in the driver, but the buffer that is binded is
* empty, so no rows will be found. This of course assumes that the
table
* doesn't contain any empty records for the "text1" column, which is
correct
* for our test. Then when we call SQLExcute, the driver will realize it
has
* already done the query work and will not do it again, even though our
* buffer for parameter substitution has changed (next line of code below
* this comment).
*****************************************/
Zip file is attached. The code is currently set up to fail, but I describe
in my comments that you can uncomment the code that sets the buffer before
SQLNumResultCols to make things will work.
Thanks for your attention,
Keith Millard
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Attachments:
pgodbc_test.zip (application/octet-stream, 3.7K) download
execute.c (application/octet-stream, 21.0K) download
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To: pgsql-interfaces@postgresql.org
Cc: Kmillard@pumatech.com
Subject: Re: Postgres odbc driver bug
In-Reply-To: <D7058849BACBD411B0E900508BFDF7DA4BFE2A@MAILNH01>
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