ALTER TABLE source SHRINK SPACE

ALTER TABLE source modify lob(FILE_F) (SHRINK SPACE cascade)

select SEGMENT_NAME, SEGMENT_TYPE, OWNER
 from dba_extents where file_id = 78 and
2272847 between block_id and block_id + blocks -1

SEGMENT_NAME               SEGMENT_TYPE  OWNER                         
-------------------------- ------------- ------
SYS_LOB0000052671C00008$$  LOBSEGMENT    ROOT

DECLARE
N              number; 
source_file_f  blob;
error_1578     exception;
pragma exception_init(error_1578, -1578);

BEGIN

  for T1 in (select SOURCE.rowid as source_rowid from SOURCE) LOOP 
            
  select SOURCE.file_f into source_file_f from SOURCE where SOURCE.rowid = T1.source_rowid; 

    begin N := dbms_lob.instr(source_file_f, hextoraw('889911'));
     exception 
      when error_1578 then 
      insert into ROWID1 values(T1.source_rowid); commit;
    end;

  end LOOP;

END;