RE: Magic Number

Ok so... Scott's suggestion, although making complete sense, does not
work. Rick's formula is what I used before but after a trip to the
benchmark center I was made aware that you should try to get as many
rows on the fetch as you can and let the optimizer determine what the
blocking size should be. So I usually use the 32766 which works fine on
most of our tables. However, in this particular scenario the row length
is so long that it craters. With Scott's suggestion I bumped the number
down to even 8000 and still no go. I settled on 6000 for now but I
would still like to know at what number the magic happens and why.

~Zach
-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx
[mailto:rpg400-l-bounces@xxxxxxxxxxxx] On Behalf Of
Rick.Chevalier@xxxxxxxxxxxxxxx
Sent: Thursday, June 26, 2008 3:40 PM
To: rpg400-l@xxxxxxxxxxxx
Subject: RE: Magic Number


Zach,

I do a lot of multiple record fetching and the formula I use is (128 *
1024)/recordlength = number of rows to fetch, rounded down.

This is based on the buffer size for a SQL table read. The last I saw
the buffer is 128k. I divide that by the record length and round down.
So far I haven't run into any size issues. I haven't tried Scott's
suggestion so it might be possible to fetch more rows than I normally
do.

HTH,

Rick

-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx
[mailto:rpg400-l-bounces@xxxxxxxxxxxx] On Behalf Of Zachary Johnson
Sent: Thursday, June 26, 2008 2:25 PM
To: rpg400-l@xxxxxxxxxxxx
Subject: Magic Number

Hello all...





I'm doing a multiple row fetch.

I have a table with a row length of 1958 bytes. I'm fetching it to an
array that has 8566 elements defined as an external data structure over
that table. So the math says I have 15.9952431 Mb in the array. I'm
getting MCH0601 (space offset error) followed by CPF5257 then SQL0904
type 13 reason code 423 which is "Resource Limit Exceeded". So it tells
me to reduce the number of rows in the fetch. So I do that, I reduce it
to give me 15.8 Mb. It still errors. So I am just reducing the number
till it works. But my question is, is there some sort of magic number I
need to use for the number of rows to fetch to get right up against the
maximum records I can return? I am doing all of this under the
assumption that there is a max of 16Mb on a multiple row fetch.





~Zach



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