Pages show as "used" in empty chunk

IDS 12.10.FC12 Solaris 10 1/13 Folks, A tutorial question... I was playing around with dbspaces during the past few days. I created a brand new dbspace (a single chunk). So, it is completely empty (except for 53 pages [reserved pages, I presume]). I then dbimported a database (from a prior dbexport). All the database objects were in this single dbspace (tables, indexes, simple large objects, and catalog). Nothing from any other database was put into this dbspace. Then, I DROPed the database. Server Studio confirms zero objects now present in the chunk. But, it also shows 4003 pages of space as "used". I can't "repack" or "shrink" because those functions require a table name as an input parameter, and no tables are present. The question is, after dropping the database, why am I not exactly back to where I was when I first created the dbspace, and before importing anything into it? That is, why don't I, once again, see an empty dbspace (with 53 pages used)? Thank you. David Grove #Informix

Below is an example of a empty dbspace. 53 pages used where dbspace:TBLSpace taking up 50 pages initially. Dbimport would have resulted in dbspace:TBLSpace to grow and allocate more extents. Even though the database has been dropped, the TBLSpace would still be there and not removed. You can verify your dbspace usage using oncheck -pe <dbspace name>. DBspace Usage Report: dbs8k Owner: informix Created: 04/21/2020 Chunk Pathname Pagesize(k) Size(p) Used(p) Free(p) 3 /u1/chunks/ol_test13/dbs8k 8 2500 53 2447 Description Offset(p) Size(p) ------------------------------------------------------------- -------- -------- RESERVED PAGES 0 2 CHUNK FREELIST PAGE 2 1 dbs8k:'informix'.TBLSpace 3 50 FREE 53 2447 Total Used: 53 Total Free: 2447 ------------------------------ CASEY TAN ------------------------------

Run oncheck -pe and look at what is in the chunk - first guess would be a tblspace Paul Watson Oninit LLC +1-913-387-7529 www.oninit.com Oninit® is a registered trademark of Oninit LLC

Ah, Thank you. I forgot about the TBLSPACE. I've already dropped that dbspace and am recreating it for some additional stuff I am testing, so I can't immediatley try this. But, I wonder if I could "shrink" it, and then observe the size to be back to the original extent? DG ------------------------------ David Grove ------------------------------

Thank you, Paul. You and Casey are spot on. Our databases have been running for years. I haven't fooled around with dbspace alterations for a long time. Color me red. DG ------------------------------ David Grove ------------------------------

Not possible to shrink TBLSPACE. You can use onspace -ef and -en option to control the sizing though. ------------------------------ Casey Tan ------------------------------

I think there is a RFE for shrinking the tblspace, actually thought it had made FC3 but ..... Cheers Paul Paul Watson Oninit LLC +1-913-387-7529 www.oninit.com Oninit® is a registered trademark of Oninit LLC

David: You created almost 4,000 objects in the database you created so there are 4,003 Tabelspace Tablespace pages (header pages for each table or index) that were created. A new dbspace starts out with an empty Tablespace which is initially created with 100 pages when the first table is created there and extended as needed. No problem, you should still be able to drop the dbspace since those tablespace pages are now empty. You can see those pages both in an oncheck -pe report and in sysmaster:systabnames and sysmaster:sysextents. Art Art S. Kagel, President and Principal Consultant ASK Database Management www.askdbmgt.com Blog: http://informix-myview.blogspot.com/ Disclaimer: Please keep in mind that my own opinions are my own opinions and do not reflect on the IIUG, nor any other organization with which I am associated either explicitly, implicitly, or by inference. Neither do those opinions reflect those of other individuals affiliated with any entity with which I am affiliated nor those of the entities themselves.

Art: Thank you. Except for the occasional addition of chunks, most of our Informix instances have had the same space layout for many years. I just didn't have to deal with dbspace issues. I am now engaged in a re-organization of much of our Informix disk layouts. As is obvious, I just didn't immediately recall some of the Informix architectural basics. DG ------------------------------ David Grove ------------------------------