Friday, December 09, 2005

Scaling VFP applications

So after my last post, I thought "hmmm---how does one ensure their application IS scalable?"

Here's a good definition.
Rick talks about it here but it's all about the web.

Kevin talks about it when discussing the Mere Mortals framework here but again all about the web.

The BlackBean site has a great repository of these and other articles.

But once again, most of the articles deal with web-based VFP applications. No surprise there, I suppose. The fundamentals are typically the same and if you really want a scalable application, why not deal with an environment where there may be a million users coming in from all areas instead of your standard applications.

What's great though - is the summary of Rick's To SQL or not to SQL. Using VFP data was recommended as a local data source for retrieving data.

"When we converted from local data to a SQL backend data access turned more between 2-3x slower for short requests and up to 5-10times slower for complex queries. "

The downside: "The site needs to import new Inventory data several times a day and it was necessary to import it while the site was still running in live mode, while people were reading this data. This tended to corrupt indexes frequently causing mysterious crashes and data consistency errors. "

Ah, the index - the glory and bane of a FoxPro developer's existence!

But to note: "Overall performance of the site applications dropped by about 50% when the move to SQL Server occurred. This is something you should plan on if you make the move from local data." However "The main reason for the move to SQL at Surplus was for better stability."

After you take away, it's the design of the system that counts - and as Randy Jean noted in a comment on the original post, "it's not just code design , poor database design (and management) will cause all sorts (of) scaleability issues."

So how should you work with server data? Consider the ideas noted here and here on the Wiki

Of course as with the Wikipedia, all information shown here is deemed to be true until proven false.

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