Sorry that example was supposed to read:
SELECT TOP 1 OrdNo FROM Orders WHERE OrdNo > cLastOrdNo ;
AND Left(OrdNo,1) = cDept ORDER BY OrdNo
* takes 50 seconds
SELECT OrdNo FROM Orders INTO TABLE OrdersNoOnly
INDEX ON OrdNo TAG OrdNo
INDEX ON LEFT(OrdNo,1) TAG Dept
SELECT TOP 1 OrdNo FROM OrdersNoOnly WHERE OrdNo > cLastOrdNo ;
AND Left(OrdNo,1) = cDept ORDER BY OrdNo
* takes 0.7 seconds
> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf
> Of NickC
> Sent: 09 September 2008 18:15
> To: 'ProFox Email List'
> Subject: RE: SQL > not optimised
>
> Hi all, thanks for the suggestions so far. However, this definitely seems
> to be down to the size of the table more than anything else.
>
> Beyond a certain size MIN(), MAX() and TOP 1 all stop working even though
> SYS(3054) still reports full optimization! Any ideas if this max working
> table size can be changed by some memory setting or other?
>
> Example:
>
> SELECT TOP 1 OrdNo FROM OrdersNoOnly WHERE OrdNo > cLastOrdNo ;
> AND Left(OrdNo,1) = cDept ORDER BY OrdNo
> * takes 50 seconds
>
> SELECT OrdNo FROM Orders INTO TABLE OrdersNoOnly
> INDEX ON OrdNo TAG OrdNo
> INDEX ON LEFT(OrdNo,1) TAG Dept
>
> SELECT TOP 1 OrdNo FROM OrdersNoOnly WHERE OrdNo > cLastOrdNo ;
> AND Left(OrdNo,1) = cDept ORDER BY OrdNo
> * takes 0.7 seconds
>
> Nick
>
>
> > -----Original Message-----
> > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
> Behalf
> > Of NickC
> > Sent: 07 September 2008 18:18
> > To: 'ProFox Email List'
> > Subject: RE: SQL > not optimised
> >
> > Slight progress but no idea why!
> >
> >
> > Three ways that don't work (too slow):
> >
> > SELECT MIN(OrdNo) FROM Orders WHERE OrdNo > cLastPONum
> >
> > SELECT TOP 1 OrdNo FROM Orders WHERE OrdNo > cLastPONum ORDER BY OrdNo
> ASC
> >
> > SELECT * FROM Orders WHERE OrdNo IN ;
> > (SELECT TOP 1 OrdNo FROM Orders WHERE OrdNo > cLastPONum ;
> > ORDER BY OrdNo ASC)
> >
> >
> > And one way that does work:
> > SELECT OrdNo FROM Orders WHERE OrdNo > cLastPONum ORDER BY OrdNo INTO
> > CURSOR
> > Temp1
> > cOrdNo = Temp1.OrdNo
> >
> > However put a MIN, MAX or TOP 1 on and it goes excruciatingly slow
> again.
> >
> > Nick
> >
> >
> >
> >
[excessive quoting removed by server]
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