Re: MS Access 2007 update write conflict problem & resolution

When connected to ODBC source Access ignores locking steps. I don't think that's the problem.

If memory serves, when Access is building the UPDATE command automatically the WHERE clause includes every single column being updated when the old values, something like this

Update set col =145, col2 = 'jjj', col4 = '12/01/10 10:05:5.032' where
col =oldvalue1 and col2 = 'jjj' and col4 = '12/01/10 10:05:5.03'

this means it will not find the record returning the error you see.

to over come this very annoying feature you have to manually specify the update commands and the key to use.

---- Message from mailto:richard(dot)broersma(at)gmail(dot)com Richard Broersma richard(dot)broersma(at)gmail(dot)com at 03-19-2010 01:12:35 PM ------

On Fri, Mar 19, 2010 at 11:12 AM, justin(at)magwerks(dot)com
justin(at)magwerks(dot)com wrote:

The bigger problem is using time stamps to find the record for updating

Timestamps will not be unique as more than 1 record can have the same value

I suggest changing the updating method to use a unique key.

MS-Access achieves optimistic locking by listing all of the columns in
a table in the WHERE clause of the UPDATE statement. If ms-access
unable to fully represent the data stored in a postgresql table,
Access will throw back update conflict errors when postgres doesn't
update the record due to the truncated data values. I've also seen
this with null valued boolean fields.

Part of the solution would be configure the ODBC driver to use
PostgreSQL's xmin for optimistic locking. Of-course this doesn't fix
MS-Accesses inability to handle the ranges of many of PG data-types.

--
Regards,
Richard Broersma Jr.

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