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Desmond Leung wrote on Fri, 15 May 1998 18:09:24 +0800 :

> Hi,
> 
> Does any one know how to pack an record to
> the same length as Microsoft jet database engine
> default memory page(2K) to enhance concurrency
> and preformance.

just calculate the memory useage of your current records and add
another (text)field as long as the difference to the next 2k barrier.

That doesn't work if you use memo fields, because their length isn't
fixed.


  Sascha

-- 
s.w@gmx.de
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In article <355e0514.0@news.piro.net>, Sascha Wostmann <s.w@gmx.de> wrote:
>Desmond Leung wrote on Fri, 15 May 1998 18:09:24 +0800 :
>> Does any one know how to pack an record to
>> the same length as Microsoft jet database engine
>> default memory page(2K) to enhance concurrency
>> and preformance.
>
>just calculate the memory useage of your current records and add
>another (text)field as long as the difference to the next 2k barrier.

AFAIK, Access normally stores text null terminated so this won't work.  Ie.
a 2048 byte record with only "Hi Bob" in it won't be stored as 2K.  You
may be able to specify this behaviour somewhere, or worst come to worst 
you'll just have to write your own padding routine.

>That doesn't work if you use memo fields, because their length isn't
>fixed.

Certainly you're right there.
--
Jeremy Konopka             konopka at cs dot uregina dot ca

Hi Jeremy Konopka,

I want to know how to count the memory usage of a record?
How can I find out this information from MDB file?

Many Thanks,

Desmond Leung

<- Replace with ca wrote in message <6jlbjf$shc$1@sue.cc.uregina.ca>...
>In article <355e0514.0@news.piro.net>, Sascha Wostmann <s.w@gmx.de> wrote:
>>Desmond Leung wrote on Fri, 15 May 1998 18:09:24 +0800 :
>>> Does any one know how to pack an record to
>>> the same length as Microsoft jet database engine
>>> default memory page(2K) to enhance concurrency
>>> and preformance.
>>
>>just calculate the memory useage of your current records and add
>>another (text)field as long as the difference to the next 2k barrier.
>
>AFAIK, Access normally stores text null terminated so this won't work.  Ie.
>a 2048 byte record with only "Hi Bob" in it won't be stored as 2K.  You
>may be able to specify this behaviour somewhere, or worst come to worst
>you'll just have to write your own padding routine.
>
>>That doesn't work if you use memo fields, because their length isn't
>>fixed.
>
>Certainly you're right there.
>--
>Jeremy Konopka             konopka at cs dot uregina dot ca

Desmond Leung wrote on Mon, 18 May 1998 11:32:42 +0800 :

> I want to know how to count the memory usage of a record?
> How can I find out this information from MDB file?

look into the online-help about data variable declaration (or alike,
search for "integer data type")

Byte            1 Byte
Boolean         2 Bytes
Integer         2 Bytes
Long            4 Bytes
Single          4 Bytes
Double          8 Bytes
Currency        8 Bytes
Date            8 Bytes
Object          4 Bytes
Memo           10 Bytes + Length of Text (10 - ~2,000,000,000)
String(fixed)  Length of Text (1 - ~2,000,000,000)



  Sascha

-- 
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Hi Desmond,

In article <6jo9o0$8eo$1@dover.cityu.edu.hk>,
Desmond Leung <ckkleung@cs.cityu.edu.hk> wrote:
>I want to know how to count the memory usage of a record?

Well, if you can have a fixed text field then it's going to be 
1 character=1 byte so it's easy.  Things like integers will be 4 bytes, so
what you then basically do is add it up.  I don't know how practical this
would be..  Certainly I've never done it.

>How can I find out this information from MDB file?

You've got me there.  Since Access scrunches everything inside one big file,
you'd have a tough time figuring it out...

You're probaby just going to have to live with multiple records being locked
at one time.

>>AFAIK, Access normally stores text null terminated so this won't work.  Ie.
>>a 2048 byte record with only "Hi Bob" in it won't be stored as 2K.  You
>>may be able to specify this behaviour somewhere, or worst come to worst
>>you'll just have to write your own padding routine.
--
Jeremy Konopka             konopka at cs dot uregina dot ca

Yes, I want to reduce the chance of locking multiple record on the same
memory page

Desmond Leung

Replace with CA wrote in message <6jsqv7$leu$1@sue.cc.uregina.ca>...
>Hi Desmond,
>
>In article <6jo9o0$8eo$1@dover.cityu.edu.hk>,
>Desmond Leung <ckkleung@cs.cityu.edu.hk> wrote:
>>I want to know how to count the memory usage of a record?
>
>Well, if you can have a fixed text field then it's going to be
>1 character=1 byte so it's easy.  Things like integers will be 4 bytes, so
>what you then basically do is add it up.  I don't know how practical this
>would be..  Certainly I've never done it.
>
>>How can I find out this information from MDB file?
>
>You've got me there.  Since Access scrunches everything inside one big
file,
>you'd have a tough time figuring it out...
>
>You're probaby just going to have to live with multiple records being
locked
>at one time.
>
>>>AFAIK, Access normally stores text null terminated so this won't work.
Ie.
>>>a 2048 byte record with only "Hi Bob" in it won't be stored as 2K.  You
>>>may be able to specify this behaviour somewhere, or worst come to worst
>>>you'll just have to write your own padding routine.
>--
>Jeremy Konopka             konopka at cs dot uregina dot ca

By the way, if optimistic locking is workable for you, it should greatly
reduce page locking conflicts since the page is only locked for a fraction
of a second during the save.