Re: using Select SQL syntax and performance issues
- From: "Dan Freeman" <spam@xxxxxxxxxxxxx>
- Date: Fri, 30 Dec 2005 08:42:28 -0800
Foxpro's SQL implementation works best with subsets.
If you just want to move an entire table to a temp table, use the COPY
command.
With a table of any size (and without joins), REPLACE will almost always be
faster than UPDATE.
Generally, slow queries are the result of a lack of Rushmore optimization.
See the help file for more information.
Dan
ddobier wrote:
> Hello. I'm new to foxpro but have a VB and sql server background. I'm
> trying to rewrite some existing foxpro programs that are very
> inefficient. What I'm noticing is that the majority of my sql
> statements are very slow to process. The table I'm either updating or
> searching through has approx 150000 records. Here's what I'm seeing:
>
> update cust set is_new = .T. - This statement takes about 4 minutes to
> execute. If I change it to use the replace function it processes
> immediately. I would think it would to the same for the update
> statement as I'm updating all records. Any thoughts as to why this is
> taking so long?
>
> select field1, field2, field3, field4 into cursor1 readwrite - this
> takes
> 1.5 minutes to process 150000 records. I would think this would be
> almost instantaneous as it's displaying all records. What gives? I
> moved the data files locally and see the same sluggish performance.
>
> To summerize, any sql command I give is very slow. Is this just how
> Foxpro is with sql statements? On some other SELECTS that are slow I
> checked and it's using the indexes for the joins. Is there some
> configuration option I must set like packet size, batch size, ....?
>
> Thanks for any assistance you may provide.
.
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