x$ktfbue for locally managed tablespaces and from fet$ and uet$ for dictionary managed tablespaces. select ext.owner, ext.segment_name, ext.segment_type, ext.partition_name, ext.tablespace_name, ext.extent_id, ext.block_id, ext.blocks, ext.bytes / 1024 kb, ext.file_id, ext.relative_fno from dba_extents ext;