Search notes:

Oracle: DBA_SEGMENTS

dba_segments comes in the three variants user_segments, dba_segments and cdb_segments.

dba_segments records storaged. allocated for segments

List a user's segment in descending order of their sizes:

select
   seg.tablespace_name,
   seg.segment_name,
   seg.segment_type,
   round(seg.bytes    / 1024/1024, 1) mb,
   round(seg.max_size / 1024/1024, 1) max_size_mb, 
   seg.extents,
   seg.partition_name,
   seg.segment_subtype                              -- ASSM, MSSM, SECUREFILE or null, compare with segment_space_management in dba_tablespaces
from
   dba_segments seg
where
   seg.owner = 'RENE'
order by
   seg.bytes           desc,
   seg.tablespace_name
;

TODO

user_segments does not have the columns header_file and header_block. These two numbers identify the data block of the segment header.

There is a segment with segment_type = 'SYSTEM STATISTICS and segment_name = 'HEATMAP'.

Oracle: DBA_SEGMENTS

TODO

See also