DELETE FROM GL_ACCOUNT WHERE GL_ACCT_ID IN (SELECT GL.GL_ACCT_ID FROM GL_ACCOUNT GL WHERE GL.BU_ID !=609);

SELECT COUNT(*) FROM GL_ACCOUNT;

  COUNT(*)
----------
      7098

1 row selected.

SELECT COUNT(*) FROM GL_ACCOUNT GL WHERE GL.BU_ID !=609;

  COUNT(*)
----------
      6552

1 row selected.

 what is "HWM is "excessive"

then some benefit may be obtained by rebuilding table itself.

create or replace
  procedure show_space
  ( p_segname in varchar2,
    p_owner   in varchar2 default user,
    p_type    in varchar2 default 'TABLE' )
  as
      l_free_blks                 number;
  
      l_total_blocks              number;
      l_total_bytes               number;
      l_unused_blocks             number;
      l_unused_bytes              number;
      l_LastUsedExtFileId         number;
      l_LastUsedExtBlockId        number;
      l_LAST_USED_BLOCK           number;
      procedure p( p_label in varchar2, p_num in number )
      is
      begin
          dbms_output.put_line( rpad(p_label,40,'.') ||
                                p_num );
      end;
  begin
      dbms_space.free_blocks
      ( segment_owner     => p_owner,
        segment_name      => p_segname,
        segment_type      => p_type,
        freelist_group_id => 0,
        free_blks         => l_free_blks );
  
      dbms_space.unused_space
      ( segment_owner     => p_owner,
        segment_name      => p_segname,
        segment_type      => p_type,
        total_blocks      => l_total_blocks,
        total_bytes       => l_total_bytes,
        unused_blocks     => l_unused_blocks,
        unused_bytes      => l_unused_bytes,
        LAST_USED_EXTENT_FILE_ID => l_LastUsedExtFileId,
        LAST_USED_EXTENT_BLOCK_ID => l_LastUsedExtBlockId,
        LAST_USED_BLOCK => l_LAST_USED_BLOCK );
  
      p( 'Free Blocks', l_free_blks );
      p( 'Total Blocks', l_total_blocks );
      p( 'Total Bytes', l_total_bytes );
      p( 'Unused Blocks', l_unused_blocks );
      p( 'Unused Bytes', l_unused_bytes );
      p( 'Last Used Ext FileId', l_LastUsedExtFileId );
      p( 'Last Used Ext BlockId', l_LastUsedExtBlockId );
      p( 'Last Used Block', l_LAST_USED_BLOCK );
  end;
/

select /*+ all_rows */ count(1) 
from
 "OFFLINETESTDB"."GL_ACCOUNT_QUARTERLY_STAT" where "GL_ACCT_ID" = :1 and 
  "GL_ACCT_NO" = :2


call     count       cpu    elapsed       disk      query    current        rows
------- ------  -------- ---------- ---------- ---------- ----------  ----------
Parse        1      0.00       0.00          0          0          0           0
Execute      3      0.00       0.06          0          0          0           0
Fetch        3      1.64      20.79     108398     109500          0           3
------- ------  -------- ---------- ---------- ---------- ----------  ----------
total        7      1.64      20.86     108398     109500          0           3

Misses in library cache during parse: 1
Misses in library cache during execute: 1
Optimizer mode: ALL_ROWS
Parsing user id: SYS   (recursive depth: 1)

Rows     Row Source Operation
-------  ---------------------------------------------------
      3  SORT AGGREGATE (cr=109500 pr=108398 pw=0 time=20797344 us)
      0   TABLE ACCESS FULL GL_ACCOUNT_QUARTERLY_STAT (cr=109500 pr=108398 pw=0 time=20797279 us)

********************************************************************************

select /*+ all_rows */ count(1) 
from
 "OFFLINETESTDB"."GL_ACCOUNT_MONTHLY_STAT" where "GL_ACCT_ID" = :1 and 
  "GL_ACCT_NO" = :2


call     count       cpu    elapsed       disk      query    current        rows
------- ------  -------- ---------- ---------- ---------- ----------  ----------
Parse        2      0.00       0.00          0          0          0           0
Execute      4      0.00       0.06          0          0          1           0
Fetch        3      0.75      10.11      52140      59532          0           3
------- ------  -------- ---------- ---------- ---------- ----------  ----------
total        9      0.75      10.18      52140      59532          1           3

Misses in library cache during parse: 1
Misses in library cache during execute: 1
Parsing user id: SYS

Rows     Row Source Operation
-------  ---------------------------------------------------
      3  SORT AGGREGATE (cr=59532 pr=52140 pw=0 time=10116280 us)
      0   TABLE ACCESS FULL GL_ACCOUNT_MONTHLY_STAT (cr=59532 pr=52140 pw=0 time=10116221 us)

CREATE INDEX ... ON GL_ACCOUNT_QUARTERLY_STAT ( GL_ACCT_ID, GL_ACCT_NO ) ...

CREATE INDEX ... ON GL_ACCOUNT_MONTHLY_STAT ( GL_ACCT_ID, GL_ACCT_NO ) ...