I have experienced a sudden increase in my database ie mdf ,since last 2 days hardly there is a 2mb of data being entered i found there is an increase of 400mb.
can any body let me know the reason for this unexpected growth and remedy for the same.
for info i observed the show-contig report and found fragmentation is under control.
prompt reply will be highly appriciated

Are you using Informix?
What is mdb? a database?
How do you calculate the size of yr database? With onstat -d?
You can check table per table what the growth is.

If you are using IDS, check the sysptnhdr table in sysmaster database.
do a sum of the pages columns. Here you can see the difference between allocated space and actually used space.

I assume a table allocated a big extent in your dbspace.
sysextents holds this info.