If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below.

 
Go Back  dBforums > Database Server Software > Informix > Extents

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
  #1 (permalink)  
Old 01-03-03, 09:32
georgipa georgipa is offline
Registered User
 
Join Date: Dec 2002
Location: Madrid - Spain
Posts: 283
Angry Extents

Hi,

I need the formula to calculate the extents size and next entents size, and too I have a good performance in the comunication the two server.

Thank you.
Reply With Quote
  #2 (permalink)  
Old 01-06-03, 07:27
Roelwe Roelwe is offline
Registered User
 
Join Date: Aug 2002
Location: Belgium
Posts: 534
There is no standard formula to calculate extent sizes.
Just try to have the least extents as possible per table.
The least number of extents give the best performance.
__________________
rws
Reply With Quote
  #3 (permalink)  
Old 01-07-03, 02:09
ladwig ladwig is offline
Registered User
 
Join Date: May 2002
Location: Osnabrueck Germany
Posts: 59
Hi,
thats what we learned
page size(2048 or 4096 or ...)
minus 24 (page header)
minus 4 (page trailer)
minus 56 (partition header)
minus number of columns *4
minus (number of keys *12) + (4 *number ob key parts)

1.add 8 bytes to the length of key
2.sum up all index entries
3.add 25% to the sum from step 2
4.guess the # of initial rows
5.multiply the result of step3 by the number of rows from step4
6.divide index space by 1024
7.subtrac 32 from the page size
8.sum up all column length in the row
9.divide page size from step 7 by row length in the step 8 and round down to the greatest whole number.
10.divide the number of rows from step 4 by the number of rows per page in step 9, round up.
11.multipy the number of pages determined in step 10 by the size of a full page
12.divide step 11 by 1024
13.add the results of step 12 and step6

estimate table growth
14. guess the number of subsequent rows
15.repeat steps 5-6 for index space and steps 10-13 for data space.
use the estimate in step 14 as the number of rows in step 5 and 10.
divide the final result by 7
__________________
Juergen Ladwig
Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On