Re: Data Dictionary: relative_fno question

xux_at_informa.bio.caltech.edu (Xuequn Xu) wrote in message news:<b04lk3$q0d$1_at_naig.caltech.edu>...
> This is normal. The relative_fno (as well as the header_file column) in
> dba_segments view indicates the file number of the datafile that the
> segment header resides, and as you know one segment can span more than one
> data file. Those "missing" FNO in the view simply means those datafiles
> have no segment header - they are occupied by the "body" of data segments
> whose header is elsewhere (in other FNOs). If you really want to get a full
> list of FNOs (for datafiles that has data in them), you can check the
> dba_extents view - go one step further in a more detail level. A
> select distinct relative_fno from dba_extents will get you a full list
> of FNOs as you see from dba_data_files (as long as every datafile has data,
> i.e. extents, in it).
>

Hi Jan,

Just to add to what Xuequn has said, note that Oracle places the first extent (which obviously contains the segment header) into the first data file listed in the tablespace (based on rfn). This means that unless the first data file is full (or sufficiently full not to be able to cope with the first extent size), all segment headers will be found in this first datafile, hence giving you this result.

Scale away !!

Richard Received on Wed Jan 15 2003 - 23:01:14 CST