[AccessD] Data from Informix to Access - dirty reads?

Jim DeMarco Jdemarco at hudsonhealthplan.org
Mon Jan 24 15:08:42 CST 2005


XML has high overhead when working with large files using the XML DOM.  If you have a large document you can use a SAX parser if you can read straight throught the file moving forward only.  It's quite a bit harder to use than the DOM though.  Part of the DOMs overhead is due to its ability to walk up and down the tree structure at random as needed.

XML does sound like a possibility here though.

Jim DeMarco

-----Original Message-----
From: accessd-bounces at databaseadvisors.com
[mailto:accessd-bounces at databaseadvisors.com]On Behalf Of John W. Colby
Sent: Monday, January 24, 2005 3:58 PM
To: 'Access Developers discussion and problem solving'
Subject: RE: [AccessD] Data from Informix to Access - dirty reads?


How much data?  Can it export it to an XML file in a location where your fe
can use it?  XML has a high overhead but can be useful in cases like this.

John W. Colby
www.ColbyConsulting.com 

Contribute your unused CPU cycles to a good cause:
http://folding.stanford.edu/

-----Original Message-----
From: accessd-bounces at databaseadvisors.com
[mailto:accessd-bounces at databaseadvisors.com] On Behalf Of Roz Clarke
Sent: Monday, January 24, 2005 10:23 AM
To: 'Access Developers discussion and problem solving'
Subject: [AccessD] Data from Informix to Access - dirty reads?


Hi all 


We have a bit of a problem with getting data out of our Informix server
since we recently turned on transaction logging for replication. When
extracting data with an Access XP MDE using pass-through queries, Access
locks entire tables in the Informix database, which causes transaction
errors and makes the Informix database scarily unstable.

Our Informix suppliers told us that the way to avoid these locking issues
was to set the connection to 'dirty read' before running the SQL. However,
Access cannot execute 2 statements in a pass-through query and it does not
hold the connection open between the execution of 1 statement and the next.
Thus when the query is processed the 'dirty read' setting is no longer in
effect.

We have been racking our brains trying to come up with a workaround. Some
further options that we have considered are:

*	Stick the data in a temp table in Informix. This is no good because
the temp table is destroyed automatically when the connection is closed and
there's no way to make it persist long enough to bind it to a report.
*	Use a view in Informix. This is no good because views in Informix
cannot be set read-only.
*	Create a permanent table in Informix and destroy it when finished
with it. This is far from ideal because Informix does not support SELECT
INTO and therefore a table would have to be explicitly constructed with
names columns etc. We really need the system to be flexible so that the
queries can be easily changed.
*	Use an ADO recordset. This is a PITA because you cannot bind a
report to a recordset in an MDE and we cannot build the report on the fly -
we are a Terminal Services site so we will have up to 20 users in one FE.
*	Create a table in Access and destroy it when finished with it. Can't
think of a better way to induce bloating...

Has anyone faced this kind of problem before? Any bright ideas? Our
foreheads are starting to bleed...

TIA

Roz (and Tom)


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