From: Marshall Barton on
John W. Vinson wrote:

>On Sun, 17 Jan 2010 10:31:55 -0600, Marshall Barton <marshbarton(a)wowway.com>
>wrote:
>
>>An alternative that can use indexes to optimize data
>>retrieval is to compare a unique indexed field to an
>>impossible value. For example, while only 99.99...%
>>guaranteed safe,
>> WHERE {increment autonumber PK field} = 0
>>will be orders of magnitude faster than WHERE False. On a
>>large table, this can make a HUGE difference.
>
>That's *very* good to know, Marshall... now I'd better go change some code in
>a couple of my clients' applications!


I am not going to set up the test cases now, but I'm
wondering if using an inner join to an indexed empty table
might be just as fast and guaranteed to work in all cases.

--
Marsh
MVP [MS Access]
From: John W. Vinson on
On Sun, 17 Jan 2010 14:47:13 -0800, Armen Stein
<ArmenStein(a)removethisgmail.com> wrote:

>>>An alternative that can use indexes to optimize data
>>>retrieval is to compare a unique indexed field to an
>>>impossible value. For example, while only 99.99...%
>>>guaranteed safe,
>>> WHERE {increment autonumber PK field} = 0
>>>will be orders of magnitude faster than WHERE False. On a
>>>large table, this can make a HUGE difference.
>>
>>That's *very* good to know, Marshall... now I'd better go change some code in
>>a couple of my clients' applications!
>
>We use Where 1=0 in SQL Server all the time, and it's very fast -
>basically instantaneous, even on large tables. The SQL Server
>optimizer must be smarter than Access in this case?

So do I, usually, and haven't had any real problems. I'm not sure if it's just
that the query is "fast enough" for my tables or if the optimizer sometimes
guesses right!
--

John W. Vinson [MVP]
From: Paul on
Armen, Banana,

Ok, I'm persuaded that I should get rid of the saving the record based on
the timer. I started doing it out of desperation over how to solve the
Write Conflict messages. But as I read through the suggestions made by all
of the experts in this thread, I'm optimistic that the problem may go away
when I incorporate those suggestions in my application. In particular:

- Moving memo fields into 1 to 1 tables,
- Loading one record at a time into the main form, instead of loading the
entire recordset and
- Making sure I'm not running action queries on the same record I'm editing
in the form without saving the record beforehand.

Thanks


From: Armen Stein on
On Sun, 17 Jan 2010 17:34:17 -0800, "Paul" <begone(a)spam.com> wrote:

>- Moving memo fields into 1 to 1 tables,
>- Loading one record at a time into the main form, instead of loading the
>entire recordset and
>- Making sure I'm not running action queries on the same record I'm editing
>in the form without saving the record beforehand.

I've heard the first suggestion many times, but we've never done it
and our apps work just fine.

I certainly recommend the other two. Maybe you could try them first
before making structural changes.

Armen Stein
Microsoft Access MVP
www.JStreetTech.com

From: Paul on
Great suggestion, Armen. Changing the tables is something that will take
days of modification and debugging, so it would require the most time and
effort. I'll try the other two first, and see what results.

Thanks much.

Paul




"Armen Stein" <ArmenStein(a)removethisgmail.com> wrote in message
news:kih7l5hc1sk37600tvi57f6oec0lb07ujl(a)4ax.com...
> On Sun, 17 Jan 2010 17:34:17 -0800, "Paul" <begone(a)spam.com> wrote:
>
>>- Moving memo fields into 1 to 1 tables,
>>- Loading one record at a time into the main form, instead of loading the
>>entire recordset and
>>- Making sure I'm not running action queries on the same record I'm
>>editing
>>in the form without saving the record beforehand.
>
> I've heard the first suggestion many times, but we've never done it
> and our apps work just fine.
>
> I certainly recommend the other two. Maybe you could try them first
> before making structural changes.
>
> Armen Stein
> Microsoft Access MVP
> www.JStreetTech.com
>


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