Walter,

It was not a "myth". It was/is a fact the thread you reference give concrete examples where it does help. You yourself give some examples where it can be beneficial.

A blanket statement that an index on deleted() is of no use is just as bad as saying a table should always have one. The real fact is it all depends. The developer needs to test to see whether it overall helps or hinders performance.

Also your admonition against the tag on deleted() may fall by the wayside once VFP9 with it's new binary index attribute ships. I will admit right now that I've not yet done any performance testing on binary indexes yet primarily because of the debug code still in the beta release.


>If you don't have a lot of deleted records in your table, there are only a few very specific circumstances that justify the use of DELETED() indexes.
>
>1. Allow the use of filtered resultsets of SQL-SELECT. Since this seldom a wanted thing, this is not a real good argument.
>
>2. Using the COUNT command on large tables.
>
>3. Finding a deleted record, though you better might use a INDEX ON .T. FOR DELETED() TAG del for that.
>
>For all other cases the use of DELETED() is complete bogus and never helps in performance issues.
>Esspecially in cases where the production app is running on a network, it could seriously degrade your performance.
>
>A few years ago, I did protest to a few MVPs/MCPs because of the use of it. I took a lot of examples and persistence to let them see the DELETED() tag was more or a burden than a help. Yes, I'm an authority on this forum regarding this subject and do have a lot of experience in optimizing queries. The missleading thing is as hilmar said is that 'full optimization' does not stand for optimal optimization.
>
>I started my rant in Thread ID: 198031 and Thread ID: 196021, more than five years ago. Shortly after this discussion an article about the issue has been written in FoxPro Advisor.
>You'll see that it took me quite a bit of effort to convince well known VFP people about the myth of the DELETED() tag.
>
>Conclusion: If you don't really need it, don't use them.