Statement using 25% CPU

Question

Hi
the following statement is taking 25% CPU to run. Although the statement completes in around 30 seconds, I have been advised that the CPU usage needs to be reduced as we can have over 4 instances of the same process running at any one time. Please can anyone make any suggestions to reduce the amount of CPU used?
The statement is:
    INSERT /*+APPEND */ INTO LINE_CALL_OVER_20P
    (ID,RUN_DATA,BILL_DATA,TEL_LINE_ID,CALL_DETS_TOTS,LINE_CALL_CHGS,LINE_TYPE,EXP_SEQ1,DESCR_CODE,AMT,DESCR_TEXT,DUR_MINS,DUR_SECS,TOTAL_AMT)
    (SELECT                      1,                                                                        -- ID
                                 U1.SITE_ID || U1.PROCESS_CTRL,                                            -- RUN DATA
                                 U1.ACCT_NUM || U1.STMT_CODE,                                              -- BILL DATA
                                 O1.SRV_ACCT_NUM||U1.CAT_CODE||U1.SRV_OCCUR,                               -- TEL LINE ID
                                 U1.ACCT_NUM || U1.SEQ_1,                                                  -- CALL DETS TOTALS
                                 1,                                                                        -- LINE CALL CHGS
                                 u1.line_type,                                                             -- LINE TYPE
                                 u1.seq_1,                                                                 -- SEQ 1
                                 u1.descr_code,                                                            -- DESCR CODE
                                 (CASE
                                  WHEN REGEXP_LIKE(SUM(u1.usage_amt), '^[0-9]+$') AND REGEXP_LIKE(SUM(u11.usage_amt), '^[0-9]+$') THEN
                                     SUM(SUBSTR(u1.usage_amt,1,LENGTH(u1.usage_amt)- 4) ||'.'|| SUBSTR(u1.usage_amt,LENGTH(u1.usage_amt)-(4+1)))
                                     - SUM(SUBSTR(u11.usage_amt,1,LENGTH(u11.usage_amt)- 4) ||'.'|| SUBSTR(u11.usage_amt,LENGTH(u11.usage_amt)-(4+1)))
                                  WHEN REGEXP_LIKE(SUM(u1.usage_amt), '^[0-9]+$') AND NOT REGEXP_LIKE(SUM(u11.usage_amt), '^[0-9]+$') THEN
                                     SUM(SUBSTR(u1.usage_amt,1,LENGTH(u1.usage_amt)- 4) ||'.'|| SUBSTR(u1.usage_amt,LENGTH(u1.usage_amt)-(4+1)))
                                     - SUM('-'||TRANSLATE(SUBSTR(u11.usage_amt,1,LENGTH(u11.usage_amt)- 4) ||'.'|| SUBSTR(u11.usage_amt,LENGTH(u11.usage_amt)- (4 + 1)),'},J,K,L,M,N,O,P,Q,R','0,1,2,3,4,5,6,7,8,9'))
                                  WHEN NOT REGEXP_LIKE(SUM(u1.usage_amt), '^[0-9]+$') AND REGEXP_LIKE(SUM(u11.usage_amt), '^[0-9]+$') THEN
                                     SUM('-'||TRANSLATE(SUBSTR(u1.usage_amt,1,LENGTH(u1.usage_amt)- 4) ||'.'|| SUBSTR(u1.usage_amt,LENGTH(u1.usage_amt)- (4 + 1)),'},J,K,L,M,N,O,P,Q,R','0,1,2,3,4,5,6,7,8,9'))
                                     - SUM(SUBSTR(u11.usage_amt,1,LENGTH(u11.usage_amt)- 4) ||'.'|| SUBSTR(u11.usage_amt,LENGTH(u11.usage_amt)-(4+1)))
                                  ELSE
                                     SUM('-'||TRANSLATE(SUBSTR(u1.usage_amt,1,LENGTH(u1.usage_amt)- 4) ||'.'|| SUBSTR(u1.usage_amt,LENGTH(u1.usage_amt)- (4 + 1)),'},J,K,L,M,N,O,P,Q,R','0,1,2,3,4,5,6,7,8,9'))
                                     - SUM('-'||TRANSLATE(SUBSTR(u11.usage_amt,1,LENGTH(u11.usage_amt)- 4) ||'.'|| SUBSTR(u11.usage_amt,LENGTH(u11.usage_amt)- (4 + 1)),'},J,K,L,M,N,O,P,Q,R','0,1,2,3,4,5,6,7,8,9'))
                                 END),
                                 h2.descr,                                                                 -- descr_text
                                 SUM(u2.USAGE_MINUTES),
                                 SUM(u2.USAGE_SECONDS),
                                 COUNT(u2.USAGE_AMT)
                            FROM stmtu1p u1,
                                 stmtu1p u11,
                                 stmtu1p u2,
                                 stmto1p o1,
                                 stmth2p h2
                           WHERE (u1.descr_code = h2.descr_code(+))
                             AND u1.acct_num          = u11.acct_num
                             AND u1.stmt_code         = u11.stmt_code
                             AND u1.srv_acct_num      = u11.srv_acct_num
                             AND u1.srv_occur         = u11.srv_occur
                             AND u1.acct_num          = u2.acct_num
                             AND u1.stmt_code         = u2.stmt_code
                             AND u1.srv_acct_num      = u2.srv_acct_num
                             AND u1.srv_occur         = u2.srv_occur
                             AND u1.acct_num          = o1.acct_num
                             AND u1.srv_acct_num      = o1.srv_acct_num
                             AND u1.stmt_code         = o1.stmt_code
                             AND u1.srv_occur         = o1.srv_occur
                             AND u1.line_type         = 'OS'
                             AND u1.seq_1             = 330
                             AND u11.line_type        = 'DZ'
                             AND u2.line_type         = 'DU'
                        GROUP BY u1.site_id,
                                 u1.process_ctrl,
                                 u1.acct_num,
                                 u1.stmt_code,
                                 O1.SRV_ACCT_NUM,
                                 o1.area_code,
                                 o1.exch_id,
                                 o1.phone_num,
                                 u1.seq_1,
                                 u1.line_type,
                                 u1.descr_code,
                                 u1.cat_code,
                                 u1.srv_occur,
                                 h2.descr)The execution plan for the statement is:
PLAN_TABLE_OUTPUT
Plan hash value: 3269235626
| Id  | Operation               | Name               | Rows  | Bytes |TempSpc| Cost (%CPU)| Time     |
|   0 | INSERT STATEMENT        |                    |    88 | 15312 |       | 19465   (5)| 00:03:54 |
|   1 |  LOAD AS SELECT         | LINE_CALL_OVER_20P |       |       |       |            |          |
|   2 |   HASH GROUP BY         |                    |    88 | 15312 |       | 19465   (5)| 00:03:54 |
|*  3 |    HASH JOIN OUTER      |                    |    88 | 15312 |       | 19464   (5)| 00:03:54 |
|*  4 |     HASH JOIN           |                    |    88 | 14344 |       | 19382   (5)| 00:03:53 |
|*  5 |      HASH JOIN          |                    |   126 | 15246 |       | 13050   (5)| 00:02:37 |
|*  6 |       HASH JOIN         |                    |  2390 |   207K|  2160K| 12816   (5)| 00:02:34 |
|*  7 |        TABLE ACCESS FULL| STMTU1P            | 47050 |  1608K|       |  6262   (5)| 00:01:16 |
|*  8 |        TABLE ACCESS FULL| STMTU1P            | 57060 |  3009K|       |  6265   (5)| 00:01:16 |
|   9 |       TABLE ACCESS FULL | STMTO1P            | 59033 |  1844K|       |   232   (7)| 00:00:03 |
|* 10 |      TABLE ACCESS FULL  | STMTU1P            |   790K|    31M|       |  6309   (6)| 00:01:16 |
|  11 |     TABLE ACCESS FULL   | STMTH2P            | 39680 |   426K|       |    80   (7)| 00:00:01 |
Predicate Information (identified by operation id):
   3 - access("U1"."DESCR_CODE"="H2"."DESCR_CODE"(+))
   4 - access("U1"."ACCT_NUM"="U2"."ACCT_NUM" AND "U1"."STMT_CODE"="U2"."STMT_CODE" AND
              "U1"."SRV_ACCT_NUM"="U2"."SRV_ACCT_NUM" AND "U1"."SRV_OCCUR"="U2"."SRV_OCCUR")
   5 - access("U1"."ACCT_NUM"="O1"."ACCT_NUM" AND "U1"."SRV_ACCT_NUM"="O1"."SRV_ACCT_NUM" AND
              "U1"."STMT_CODE"="O1"."STMT_CODE" AND "U1"."SRV_OCCUR"="O1"."SRV_OCCUR")
   6 - access("U1"."ACCT_NUM"="U11"."ACCT_NUM" AND "U1"."STMT_CODE"="U11"."STMT_CODE" AND
              "U1"."SRV_ACCT_NUM"="U11"."SRV_ACCT_NUM" AND "U1"."SRV_OCCUR"="U11"."SRV_OCCUR")
   7 - filter("U11"."LINE_TYPE"='DZ')
   8 - filter("U1"."LINE_TYPE"='OS' AND "U1"."SEQ_1"=330)
  10 - filter("U2"."LINE_TYPE"='DU')The tkprof file for the statement is:
TKPROF: Release 10.2.0.1.0 - Production on Sun Feb 17 11:29:08 2008
Copyright (c) 1982, 2005, Oracle.  All rights reserved.
Trace file: /u01/app/oracle/admin/ORATEST/udump/oratest_ora_1396968.trc
Sort options: default
count    = number of times OCI procedure was executed
cpu      = cpu time in seconds executing
elapsed  = elapsed time in seconds executing
disk     = number of physical reads of buffers from disk
query    = number of buffers gotten for consistent read
current  = number of buffers gotten in current mode (usually for update)
rows     = number of rows processed by the fetch or execute call
alter session set sql_trace=true
call     count       cpu    elapsed       disk      query    current        rows
Parse        0      0.00       0.00          0          0          0           0
Execute      1      0.00       0.00          0          0          0           0
Fetch        0      0.00       0.00          0          0          0           0
total        1      0.00       0.00          0          0          0           0
Misses in library cache during parse: 0
Misses in library cache during execute: 1
Optimizer mode: ALL_ROWS
Parsing user id: 85  (PREPROC1)
    INSERT /*+APPEND */ INTO LINE_CALL_OVER_20P
    (ID,RUN_DATA,BILL_DATA,TEL_LINE_ID,CALL_DETS_TOTS,LINE_CALL_CHGS,LINE_TYPE,EXP_SEQ1,DESCR_CODE,AMT,DESCR_TEXT,DUR_MINS,DUR_SECS,TOTAL_AMT)
    (SELECT                      1,                                                                        -- ID
                                 U1.SITE_ID || U1.PROCESS_CTRL,                                            -- RUN DATA
                                 U1.ACCT_NUM || U1.STMT_CODE,                                              -- BILL DATA
                                 O1.SRV_ACCT_NUM||U1.CAT_CODE||U1.SRV_OCCUR,                               -- TEL LINE ID
                                 U1.ACCT_NUM || U1.SEQ_1,                                                  -- CALL DETS TOTALS
                                 1,                                                                        -- LINE CALL CHGS
                                 u1.line_type,                                                             -- LINE TYPE
                                 u1.seq_1,                                                                 -- SEQ 1
                                 u1.descr_code,                                                            -- DESCR CODE
                                 (CASE
                                  WHEN REGEXP_LIKE(SUM(u1.usage_amt), '^[0-9]+$') AND REGEXP_LIKE(SUM(u11.usage_amt), '^[0-9]+$') THEN
                                     SUM(SUBSTR(u1.usage_amt,1,LENGTH(u1.usage_amt)- 4) ||'.'|| SUBSTR(u1.usage_amt,LENGTH(u1.usage_amt)-(4+1)))
                                     - SUM(SUBSTR(u11.usage_amt,1,LENGTH(u11.usage_amt)- 4) ||'.'|| SUBSTR(u11.usage_amt,LENGTH(u11.usage_amt)-(4+1)))
                                  WHEN REGEXP_LIKE(SUM(u1.usage_amt), '^[0-9]+$') AND NOT REGEXP_LIKE(SUM(u11.usage_amt), '^[0-9]+$') THEN
                                     SUM(SUBSTR(u1.usage_amt,1,LENGTH(u1.usage_amt)- 4) ||'.'|| SUBSTR(u1.usage_amt,LENGTH(u1.usage_amt)-(4+1)))
                                     - SUM('-'||TRANSLATE(SUBSTR(u11.usage_amt,1,LENGTH(u11.usage_amt)- 4) ||'.'|| SUBSTR(u11.usage_amt,LENGTH(u11.usage_amt)- (4 + 1)),'},J,K,L,M,N,O,P,Q,R','0,1,2,3,4,5,6,7,8,9'))
                                  WHEN NOT REGEXP_LIKE(SUM(u1.usage_amt), '^[0-9]+$') AND REGEXP_LIKE(SUM(u11.usage_amt), '^[0-9]+$') THEN
                                     SUM('-'||TRANSLATE(SUBSTR(u1.usage_amt,1,LENGTH(u1.usage_amt)- 4) ||'.'|| SUBSTR(u1.usage_amt,LENGTH(u1.usage_amt)- (4 + 1)),'},J,K,L,M,N,O,P,Q,R','0,1,2,3,4,5,6,7,8,9'))
                                     - SUM(SUBSTR(u11.usage_amt,1,LENGTH(u11.usage_amt)- 4) ||'.'|| SUBSTR(u11.usage_amt,LENGTH(u11.usage_amt)-(4+1)))
                                  ELSE
                                     SUM('-'||TRANSLATE(SUBSTR(u1.usage_amt,1,LENGTH(u1.usage_amt)- 4) ||'.'|| SUBSTR(u1.usage_amt,LENGTH(u1.usage_amt)- (4 + 1)),'},J,K,L,M,N,O,P,Q,R','0,1,2,3,4,5,6,7,8,9'))
                                     - SUM('-'||TRANSLATE(SUBSTR(u11.usage_amt,1,LENGTH(u11.usage_amt)- 4) ||'.'|| SUBSTR(u11.usage_amt,LENGTH(u11.usage_amt)- (4 + 1)),'},J,K,L,M,N,O,P,Q,R','0,1,2,3,4,5,6,7,8,9'))
                                 END),
                                 h2.descr,                                                                 -- descr_text
                                 SUM(u2.USAGE_MINUTES),
                                 SUM(u2.USAGE_SECONDS),
                                 COUNT(u2.USAGE_AMT)
                            FROM stmtu1p u1,
                                 stmtu1p u11,
                                 stmtu1p u2,
                                 stmto1p o1,
                                 stmth2p h2
                           WHERE (u1.descr_code = h2.descr_code(+))
                             AND u1.acct_num          = u11.acct_num
                             AND u1.stmt_code         = u11.stmt_code
                             AND u1.srv_acct_num      = u11.srv_acct_num
                             AND u1.srv_occur         = u11.srv_occur
                             AND u1.acct_num          = u2.acct_num
                             AND u1.stmt_code         = u2.stmt_code
                             AND u1.srv_acct_num      = u2.srv_acct_num
                             AND u1.srv_occur         = u2.srv_occur
                             AND u1.acct_num          = o1.acct_num
                             AND u1.srv_acct_num      = o1.srv_acct_num
                             AND u1.stmt_code         = o1.stmt_code
                             AND u1.srv_occur         = o1.srv_occur
                             AND u1.line_type         = 'OS'
                             AND u1.seq_1             = 330
                             AND u11.line_type        = 'DZ'
                             AND u2.line_type         = 'DU'
                        GROUP BY u1.site_id,
                                 u1.process_ctrl,
                                 u1.acct_num,
                                 u1.stmt_code,
                                 O1.SRV_ACCT_NUM,
                                 o1.area_code,
                                 o1.exch_id,
                                 o1.phone_num,
                                 u1.seq_1,
                                 u1.line_type,
                                 u1.descr_code,
                                 u1.cat_code,
                                 u1.srv_occur,
                                 h2.descr)
call     count       cpu    elapsed       disk      query    current        rows
Parse        1      0.03       0.04          0          0          0           0
Execute      1     12.95      18.41      28872      94074        608       39018
Fetch        0      0.00       0.00          0          0          0           0
total        2     12.98      18.46      28872      94074        608       39018
Misses in library cache during parse: 1
Optimizer mode: ALL_ROWS
Parsing user id: 85  (PREPROC1)
Rows     Row Source Operation
      1  LOAD AS SELECT  (cr=94126 pr=28872 pw=1727 time=18450373 us)
  39018   HASH GROUP BY (cr=94061 pr=28872 pw=1245 time=17322258 us)
258728    HASH JOIN OUTER (cr=94061 pr=27627 pw=0 time=12275770 us)
258728     HASH JOIN  (cr=93694 pr=27627 pw=0 time=12974313 us)
  46380      HASH JOIN  (cr=62830 pr=23324 pw=0 time=6837995 us)
  46380       HASH JOIN  (cr=61729 pr=23324 pw=0 time=9986105 us)
  46381        TABLE ACCESS FULL STMTU1P (cr=30865 pr=17444 pw=0 time=4545326 us)
  57603        TABLE ACCESS FULL STMTU1P (cr=30864 pr=5880 pw=0 time=2073762 us)
  59033       TABLE ACCESS FULL STMTO1P (cr=1101 pr=0 pw=0 time=77 us)
789379      TABLE ACCESS FULL STMTU1P (cr=30864 pr=4303 pw=0 time=793734 us)
  39954     TABLE ACCESS FULL STMTH2P (cr=367 pr=0 pw=0 time=105 us)
Rows     Execution Plan
      0  INSERT STATEMENT   MODE: ALL_ROWS
      1   LOAD AS SELECT OF 'LINE_CALL_OVER_20P'
  39018    HASH (GROUP BY)
258728     HASH JOIN (OUTER)
258728      HASH JOIN
  46380       HASH JOIN
  46380        HASH JOIN
  46381         TABLE ACCESS   MODE: ANALYZED (FULL) OF 'STMTU1P'
                    (TABLE)
  57603         TABLE ACCESS   MODE: ANALYZED (FULL) OF 'STMTU1P'
                    (TABLE)
  59033        TABLE ACCESS   MODE: ANALYZED (FULL) OF 'STMTO1P'
                   (TABLE)
789379       TABLE ACCESS   MODE: ANALYZED (FULL) OF 'STMTU1P' (TABLE)
  39954      TABLE ACCESS   MODE: ANALYZED (FULL) OF 'STMTH2P' (TABLE)
select file#
from
file$ where ts#=:1
call     count       cpu    elapsed       disk      query    current        rows
Parse        4      0.00       0.00          0          0          1           0
Execute      4      0.01       0.00          0          0          0           0
Fetch       12      0.00       0.00          0         20          0           8
total       20      0.01       0.01          0         20          1           8
Misses in library cache during parse: 1
Misses in library cache during execute: 1
Optimizer mode: CHOOSE
Parsing user id: SYS   (recursive depth: 1)
Rows     Row Source Operation
      2  TABLE ACCESS FULL FILE$ (cr=5 pr=0 pw=0 time=67 us)
update tsq$ set blocks=:3,maxblocks=:4,grantor#=:5,priv1=:6,priv2=:7,priv3=:8
where
ts#=:1 and user#=:2
call     count       cpu    elapsed       disk      query    current        rows
Parse        4      0.00       0.00          0          0          2           0
Execute      4      0.01       0.00          0         12          4           4
Fetch        0      0.00       0.00          0          0          0           0
total        8      0.01       0.01          0         12          6           4
Misses in library cache during parse: 1
Misses in library cache during execute: 1
Optimizer mode: CHOOSE
Parsing user id: SYS   (recursive depth: 1)
Rows     Row Source Operation
      0  UPDATE  TSQ$ (cr=3 pr=0 pw=0 time=267 us)
      1   TABLE ACCESS CLUSTER TSQ$ (cr=3 pr=0 pw=0 time=83 us)
      1    INDEX UNIQUE SCAN I_USER# (cr=1 pr=0 pw=0 time=27 us)(object id 11)
update seg$ set type#=:4,blocks=:5,extents=:6,minexts=:7,maxexts=:8,extsize=
  :9,extpct=:10,user#=:11,iniexts=:12,lists=decode(:13, 65535, NULL, :13),
  groups=decode(:14, 65535, NULL, :14), cachehint=:15, hwmincr=:16, spare1=
  DECODE(:17,0,NULL,:17),scanhint=:18
where
ts#=:1 and file#=:2 and block#=:3
call     count       cpu    elapsed       disk      query    current        rows
Parse        4      0.00       0.00          0          0          0           0
Execute      4      0.01       0.00          0         20          4           4
Fetch        0      0.00       0.00          0          0          0           0
total        8      0.01       0.01          0         20          4           4
Misses in library cache during parse: 1
Misses in library cache during execute: 1
Optimizer mode: CHOOSE
Parsing user id: SYS   (recursive depth: 1)
Rows     Row Source Operation
      0  UPDATE  SEG$ (cr=5 pr=0 pw=0 time=338 us)
      1   TABLE ACCESS CLUSTER SEG$ (cr=5 pr=0 pw=0 time=162 us)
      1    INDEX UNIQUE SCAN I_FILE#_BLOCK# (cr=2 pr=0 pw=0 time=24 us)(object id 9)
commit
call     count       cpu    elapsed       disk      query    current        rows
Parse        1      0.00       0.00          0          0          0           0
Execute      1      0.00       0.00          0          2         35           0
Fetch        0      0.00       0.00          0          0          0           0
total        2      0.00       0.00          0          2         35           0
Misses in library cache during parse: 0
Parsing user id: 85  (PREPROC1)
alter session set sql_trace=false
call     count       cpu    elapsed       disk      query    current        rows
Parse        1      0.00       0.00          0          0          0           0
Execute      1      0.00       0.00          0          0          0           0
Fetch        0      0.00       0.00          0          0          0           0
total        2      0.00       0.00          0          0          0           0
Misses in library cache during parse: 1
Optimizer mode: ALL_ROWS
Parsing user id: 85  (PREPROC1)
OVERALL TOTALS FOR ALL NON-RECURSIVE STATEMENTS
call     count       cpu    elapsed       disk      query    current        rows
Parse        3      0.03       0.04          0          0          0           0
Execute      4     12.95      18.42      28872      94076        643       39018
Fetch        0      0.00       0.00          0          0          0           0
total        7     12.98      18.47      28872      94076        643       39018
Misses in library cache during parse: 2
Misses in library cache during execute: 1
OVERALL TOTALS FOR ALL RECURSIVE STATEMENTS
call     count       cpu    elapsed       disk      query    current        rows
Parse       12      0.00       0.01          0          0          3           0
Execute     12      0.03       0.01          0         32          8           8
Fetch       12      0.00       0.00          0         20          0           8
total       36      0.03       0.03          0         52         11          16
Misses in library cache during parse: 3
Misses in library cache during execute: 3
    4  user  SQL statements in session.
   12  internal SQL statements in session.
   16  SQL statements in session.
    1  statement EXPLAINed in this session.
Trace file: /u01/app/oracle/admin/ORATEST/udump/oratest_ora_1396968.trc
Trace file compatibility: 10.01.00
Sort options: default
       1  session in tracefile.
       4  user  SQL statements in trace file.
      12  internal SQL statements in trace file.
      16  SQL statements in trace file.
       7  unique SQL statements in trace file.
       1  SQL statements EXPLAINed using schema:
           PREPROC1.prof$plan_table
             Default table was used.
             Table was created.
             Table was dropped.
     232  lines in trace file.
      50  elapsed seconds in trace file.Many thanks

Answer 1

Absolutely spot on Rob. Yours is better than mine.
I was looking at something like this. Below ones will be the inner query.
select 1,                                                                        -- ID
       U1.SITE_ID || U1.PROCESS_CTRL,                                            -- RUN DATA
       U1.ACCT_NUM || U1.STMT_CODE,                                              -- BILL DATA
       O1.SRV_ACCT_NUM||U1.CAT_CODE||U1.SRV_OCCUR,                               -- TEL LINE ID
       U1.ACCT_NUM || U1.SEQ_1,                                                  -- CALL DETS TOTALS
       1,                                                                        -- LINE CALL CHGS
       u1.line_type,                                                             -- LINE TYPE
       u1.seq_1,                                                                 -- SEQ 1
       u1.descr_code,                                                            -- DESCR CODE
       sum(case when u1.line_type = 'OS'
       and u1.seq_1 = 330 then
       usage_amt
                 else 0
            end) u1_sum_usage_amt
      ,sum(decode(u1.line_type, 'DZ', usage_amt, 0)) u11_sum_usage_amt
      ,sum(decode(u1.line_type, 'DU', usa_minutes, 0)) u2_sum_minutes
      ,sum(decode(u1.line_type, 'DU', usa_seconds, 0)) u2_sum_seconds
      ,sum(decode(u1.line_type, 'DU', usage_amt, 0)) u2_sum_usage_amt
from stmtu1p u1,
     stmto1p o1,
     stmth2p h2
WHERE u1.descr_code = h2.descr_code(+)
AND u1.acct_num          = o1.acct_num
AND u1.srv_acct_num      = o1.srv_acct_num
AND u1.stmt_code         = o1.stmt_code
AND u1.srv_occur         = o1.srv_occur
AND u1.line_type         = 'OS'
AND u1.seq_1             = 330
AND u11.line_type        = 'DZ'
AND u2.line_type         = 'DU'
GROUP BY u1.site_id,
         u1.process_ctrl,
         u1.acct_num,
         u1.stmt_code,
         O1.SRV_ACCT_NUM,
         o1.area_code,
         o1.exch_id,
         o1.phone_num,
         u1.seq_1,
         u1.line_type,
         u1.descr_code,
         u1.cat_code,
         u1.srv_occur,
         h2.descrAnd then in the outer query he can have something like this.
case when REGEXP_LIKE(u1_sum_usage_amt, '^[0-9]+$') ...He should be able to change the query and gain considerable performance advantage with your start-up.
Cheers
Sarma.