mysql select some sort of caching

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---------- Forwarded message ----------
From: David Sfiligoi <sfiligoi at gmail.com>
To: python-list at python.org
Date: Tue, 20 Oct 2009 21:41:10 -0500
Subject: mysql select some sort of caching
Hi
I am normally an SQLlite person because it just works... but I decided to
keep inproving my skills set and do my new project using a MySQL database
backend because of the architecture decision I made(horizontal scalable
system via message queues). The project is architected around a rabbitmq
system with bunch of consumers(potentially large) and publishers... I
digress, the rabbit has a no part to play in my myunderstanding with
mysql.

I have a consumer that get data from a queue(a url). This queue is
checked in a loop. Once a url has been published in the queue, the
consumer sees it and call a function to do something with it.  Using a
column in the table I verify if 'today's task' has been done already
(compare the current date to the last task date that I store in the table
last time I executed the task)

So normally I would open a connection and instentiate a cursor for my
queries once at a global level(like find out if the current date is >
than the last task date). Then go in an infinite loop that wait for data
to arrive in the queue and carry the cursor and connection over.  However
this is the issue I seem to run into.  I test the code by zapping, using
mysql query tools, the table's last task date column with an older date
so that current date is larger than the current date.  Issue is that
whatever prior date I put in the table's last task date colum somehow
they are not seen by the SELECT query
sqlcur.execute("SELECT `url`d` from `url_snapshot` WHERE `url` = %s and
`lastsnapshotdate` < %s",(url,currentdate))
that query returns old data.

Just like if the query is cached....yet the data actually changed in the
database.

However when I recreate a new connection and cursor everytime I get a new
message in the queue(url), therefore within the message found loop there
are no issues seeing the last update done via the mysql query tool

I don't think this has to do with mysql caching features since its
suppose to detect when the fields changed.

Any ideas?

Thanks for your Time,
David

---------- Forwarded message ----------

A simple suggestion.. in your next post - go direct to your problem.

Just to be sure, did you got a "commit"!?
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