I'm trying to calculate the size of a few tables as stated here, but I can't find the block header size variable
How do I get it? Is it some kind of formula?
I'm using Oracle 10g
I saw that, but I think it's just one part of the "whole block header"
Juan Manuel
2009-03-05 12:41:47
The block header size is 57 bytes, did you mean the block size?
paxdiablo
2009-03-05 12:43:08
Or the actual overhead which is discussed on that page as well (block header, transaction header, table directory, ...)?
paxdiablo
2009-03-05 12:44:36
+2
A:
This site has a good discussion on the format of the block header: http://www.adp-gmbh.ch/ora/concepts/db_block.html. Basically the block header = fixed header + transaction header + table directory + row directory. Here are the individual pieces:
fixed header = 57 bytes
transaction header = between 23*inittrans and 23*maxtrans
table directory = 4*number of tables (usually 1 unless you're using clusters)
row directory = 2*stored rows
In short while you can come up with a rough estimate, it's not a fixed size for each data block.
Shawn Loewen
2009-03-05 12:41:12