DBA_SEGMENTS

Storage allocated for all database segments
Columns
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   RELATIVE_FNO
      Relative number of the file containing the segment header
   INITIAL_EXTENT
      Size, in bytes, of the initial extent of the segment
   BUFFER_POOL
      The default buffer pool to be used for segments blocks
   FREELIST_GROUPS
      Number of freelist groups allocated in this segment
   FREELISTS
      Number of process freelists allocated in this segment
   PCT_INCREASE
      Percent by which to increase the size of the next extent to be allocated
   MAX_EXTENTS
      Maximum number of extents allowed in the segment
   MIN_EXTENTS
      Minimum number of extents allowed in the segment
   NEXT_EXTENT
      Size, in bytes, of the next extent to be allocated to the segment
   BLOCKS
      Size, in Oracle blocks, of the segment
   BYTES
      Size, in bytes, of the segment
   HEADER_BLOCK
      ID of the block containing the segment header
   HEADER_FILE
      ID of the file containing the segment header
   TABLESPACE_NAME
      Name of the tablespace containing the segment
   SEGMENT_TYPE
      Type of segment:  `TABLE`, `CLUSTER`, `INDEX`, `ROLLBACK`, `DEFERRED ROLLBACK`, `TEMPORARY`,`SPACE HEADER`,  or `CACHE`
   PARTITION_NAME
      Partition/Subpartition Name, if any, of the segment
   SEGMENT_NAME
      Name, if any, of the segment
   OWNER
      Username of the segment owner
   EXTENTS
      Number of extents allocated to the segment
Related Commands:
Simon Sheppard
SS64.com