Re: Will setting BLOB to NULL free disk space

"Johan Hellstrom" <xtrnjot_at_nospam.hotmail.com> wrote in message news:<bnlgmd$3fe$1_at_newstree.wise.edt.ericsson.se>...
> If a BLOB column has around 10 MB of data in it and it is set to NULL, would
> the storage needed to store the record be reduced by 10 MB?
>
> Additionally would it leave room for another 10 MB of data on the file
> system? or would the DBMS still "claim" this space for another purpose?
>
> If this is not the case, is there an alternative preferred way of freeing up
> disk space used by LOB data for other purposes?
>
> Kind Regards
>
> Johan Hellstrom

Johan, Oracle space management policies are fairly well described in the Concepts manual chapters on Blocks, Extents, and Segments and Tablespaces and Data files which are chapters 2 and 3 in the 9.2 documentation.

Basically once space is allocated to an Oracle object the object does not release it for use by another object unless DBA intervention takes place.

HTH -- Mark D Powell -- Received on Tue Oct 28 2003 - 15:14:35 CET