Re: Postgres odbc driver bug

Keith, forget my earlier request about reviewing the patch. One of our
ODBC guys (Hiroshi) says your patch fixes a different problem.

If no one objects, I will be applying yours in a day or two. Can you
make sure my version of your patch is correct? I will change the #if 0
and just remove that code, and remove your //chuck comments.

Thanks.

> 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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