Re: Commit to odbc.c from 5/19/2010 breaks prepared statements with pyodbc

The patch add lazy prepare which improve performance and works better
with DBD::ODBC.
If I understood correctly using mssql works correct but with Sybase
server the results is not ok. Am I right?
The correct solution is fix the issue using Sybase.

freddy77

2010/10/15 Peter C. Norton <[email protected]>:
> Hi, I've got another bug report.  At my site we've run into a
> regression when going from the following:
>
> pyodbc-2.1.7
>  depends on
> unixODBC-2.2.14
>  which depends on
> freetds-0.82.1.dev.20091223
>
> to the same pyodbc and unixODBC, but upgrading to
> freetds-0.83.dev.20100902 + various patches from upstream.  When users
> tested it I got the following succinct bug report:
>
> import pyodbc
> def the_test(db_name):
>    db = pyodbc.connect("DSN=%s;UID=<USERNAME>;PWD=<PASSWORD>;DATABASE=<any database>;APP=python_test" % db_name)
>    q = db.execute("select * from <any table> where type = ?", (1,))
>    print q.fetchall()
>
> the_test("SYBASE")
>
> results in the following error:
>
> Error: ('HY000', 'The driver did not supply an error!')
>
> Confirmed on solaris x86 and linux/64-bit.  I've bisected the changes
> made back to 5/19/2010 via the freetds git repository and I found that
> the following broke prepared statements from pyodbc:
>
> http://github.com/brianb/FreeTDS/commit/2ed78ea4dd9018927b56822e318e0b5ac9401b98#diff-2
>
> Specifically the chunk between line 1301 and 1313. The relevent chunk of code is this:
>
>                if (desc->type == DESC_IRD && ((TDS_STMT*)desc->parent)->need_reprepare && \
>                    odbc_update_ird((TDS_STMT*)desc->parent, errs) != SQL_SUCCESS) \
>                        exit; \
>
> Reverting the patch to the pre-2010-05-19 state has the preprocessor
> replace the above with:
>
> #define IRD_UPDATE(desc, errs, exit) do { } while(0)
>
> which may just be masking an error, but I do not know.  Backing this
> out causes prepared statements to work again.  Are there any gotchas
> to reverting this change?  And is there a better/more correct fix for
> this?
>
> By the way, this works fine when I point the same test an an MSSQL 2005 or 2008 server.
>
> Thanks,
>
> -Peter
>
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