I have a question that has been bothering me for a while. WHY
are
goto top
and
goto bottom
not Rushmore-optimisable, yet
locate
is?

ISTM that it would have been easy enough to do.

Sincerely,

Gene Wirchenko

Computerese Irregular Verb Conjugation:
I have preferences.
You have biases.
He/She has prejudices.

Goto top
and goto bottom
have no optimizable features....

The index that's set defines top/bottom -- there's not "thinking" involved..

On Wed, 22 Dec 2004 20:12:22 -0800, Gene Wirchenko <genew (AT) mail (DOT) ocis.net> wrote:


---
Remove x's to send.

Josh Assing <xjoshx (AT) jassing (DOT) com> wrote:


Why would a plain
locate
be optimisable then? Depending on whether the index is ascending or
descending,
locate
is logicaly equivalent to
goto top
or
goto bottom

It is this discrepancy that has me wondering.

[snipped previous]

Sincerely,

Gene Wirchenko

Computerese Irregular Verb Conjugation:
I have preferences.
You have biases.
He/She has prejudices.

I believe Rushmore only kicks in when a FOR clause is used with single-table
commands. From VFP help,

"In its simplest form, Rushmore speeds the performance of single-table
commands using FOR clauses that specify sets of records in terms of existing
indexes."

I know that with FilterConditions set, SET DELETED ON, etc, GOTO could be
optimised to find which record "top" or "bottom" is, but looks like it was
never done. From the above quote from the help, does LOCATE FOR only specify
a single record rather than a recordset, or does it internally specify a
recordset to VFP for use with CONTINUE?

In the case of a clause-free LOCATE, I guess LOCATE followed by CONTINUE is
the same as GO TOP followed by SKIP, so looks like it could be optimised but
they just haven't got round to it yet. I see your point.

Cheers,
Neil

"Gene Wirchenko" <genew (AT) mail (DOT) ocis.net> wrote

LOCATE is scoped. GOTO isn't.

Dan

Gene Wirchenko wrote:

"Dan Freeman" <spam (AT) microsoft (DOT) com> wrote:

locate
and
goto top
are doing the exact same thing: finding the first record.

[snip]

Sincerely,

Gene Wirchenko

Computerese Irregular Verb Conjugation:
I have preferences.
You have biases.
He/She has prejudices.

Gene Wirchenko wrote:
differently. Locate is Rushmore optimized and go top is not. Locate
uses the index if an order is set. If no order is set and you actually
want the first physical record then go top might be the faster of the two.

--
Cy Welch
Senior Programmer
MetSYS Inc
http://www.metsysinc.com

Gene Wirchenko wrote:
And one uses a scope while the other doesn't.