log space for alter fragment

log space for alter fragment

Post by sami » Sun, 31 Dec 1899 09:00:00



Hi all,
I want to do an alter fragment on table <table> init in <dbspace>, and I
want to know how many spaces that would take in the log file.
Thanks for any help
 
 
 

log space for alter fragment

Post by Carlso » Sun, 31 Dec 1899 09:00:00



> Hi all,
> I want to do an alter fragment on table <table> init in <dbspace>, and I
> want to know how many spaces that would take in the log file.
> Thanks for any help

That would depend on the size of the table, as "ALTER TABLE" will
execute in a single transaction.  I would estimate that total space
would approach the total size of the table including indices.

I've always wanted to know how Informix stores logical log information,
but there is no definite algorithm.  At least not that I know about.

--
John Carlson
Informix DBA
WHSmith USA

#include std_disclaimer.h     /* These are my opinions, not my company's
opinion  */

 
 
 

log space for alter fragment

Post by June Ton » Sun, 31 Dec 1899 09:00:00


Quote:> That would depend on the size of the table, as "ALTER TABLE" will
> execute in a single transaction.  I would estimate that total space
> would approach the total size of the table including indices.

> I've always wanted to know how Informix stores logical log information,
> but there is no definite algorithm.  At least not that I know about.

I'm sure this is in a manual somewhere.  Something like 16 (or maybe 20,
depending on the version) plus rowsize for each row insert, 20 plus
index key size for each row for each index.  (Don't quote me on any of
this.)  The problem is estimating other things which are logged, such as
btree splits and checkpoints.

June
--

Living on Snickers bars in San Mateo