Why is my database with no data so large?

Posted by S33 on 29-Nov-2017 14:37

I created a new db via prostrct create, then did a procopy of empty8, and then loaded my existing .df file. Database remained miniscule. I then ran a script that i had created that was:
proutil mydatabase -C tablemove mytable_1 "App Data 1" "App Index 1"
for every _file. This EMPTY database grew to about 250 Mb
   84M Nov 29 15:04 mydatabase_7.d1
 176M Nov 29 15:04 mydatabase_8.d1

Is this normal/expected or did I do something I shouldn't have?

The .st file contains 2 variable extents:
d "App Data 1",128;64 /u2/appl/blah/db
d "App Index 1",1;64 /u2/appl/blah/db

This is 11.7.1 on RHEL..

Thanks in advance -- Jim

All Replies

Posted by Rob Fitzpatrick on 29-Nov-2017 14:50

Hi Jim,

The size of your database, with application schema and no data, depends on database block size, database structure, and schema contents (both number of storage objects and assignment of objects to areas).

In Type II storage areas (cluster size > 1), each storage object (table, index, or LOB column) consumes a minimum of one cluster of storage, even when empty.  Given a block size of 8 KB and a cluster size of 64 blocks, each object consumes 64 * 8192 = 512 KB, or half a megabyte.  Given your post-schema-load extent sizes, I'd guess you have about 168 tables and 352 indexes, give or take.

Posted by S33 on 29-Nov-2017 15:15

Thanks, Rob. That makes perfect mathematical sense. It probably doesn't really matter - I guess I may have added a few milliseconds to their backup time. I was just shocked because the Type I database, with data, was 9Mb.

When the customer asks "Where is the value add?" I guess I'll be able to point directly to it  :-)

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