Best way to Fetch the record

Question

Hi,
Please suggest me the best way to fetch the record from the table designed below. It is Oracle 10gR2 on Linux
Whenever a client visit the office a record will be created for him. The company policy is to maintain 10 years of data on the transaction table but the table holds record count of 3 Million records per year.
The table has the following key Columns for the Select (sample Table)
Client_Visit
ID Number(12,0) --sequence generated number
EFF_DTE DATE --effective date of the customer (sometimes the client becomes invalid and he will be valid again)
Create_TS Timestamp(6)
Client_ID Number(9,0)
Cascade Flg vahrchar2(1)
On most of the reports the records are fetched by Max(eff_dte) and Max(create_ts) and cascade flag ='Y'.
I have following queries but the both of them are not cost effective and takes 8 minutes to display the records.
Code 1:
SELECT   au_subtyp1.au_id_k,
                                   au_subtyp1.pgm_struct_id_k
                              FROM au_subtyp au_subtyp1
                             WHERE au_subtyp1.create_ts =
                                      (SELECT MAX (au_subtyp2.create_ts)
                                         FROM au_subtyp au_subtyp2
                                        WHERE au_subtyp2.au_id_k =
                                                            au_subtyp1.au_id_k
                                          AND au_subtyp2.create_ts <
                                                 TO_DATE ('2013-01-01',
                                                          'YYYY-MM-DD'
                                          AND au_subtyp2.eff_dte =
                                                 (SELECT MAX
                                                            (au_subtyp3.eff_dte
                                                    FROM au_subtyp au_subtyp3
                                                   WHERE au_subtyp3.au_id_k =
                                                            au_subtyp2.au_id_k
                                                     AND au_subtyp3.create_ts <
                                                            TO_DATE
                                                                ('2013-01-01',
                                                                 'YYYY-MM-DD'
                                                     AND au_subtyp3.eff_dte < =
                                                            TO_DATE
                                                                ('2012-12-31',
                                                                 'YYYY-MM-DD'
                               AND au_subtyp1.exists_flg = 'Y'
Explain Plan
Plan hash value: 2534321861
| Id  | Operation                | Name      | Rows  | Bytes |TempSpc| Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT         |           |     1 |    91 |       | 33265   (2)| 00:06:40 |
|*  1 |  FILTER                  |           |       |       |       |            |          |
|   2 |   HASH GROUP BY          |           |     1 |    91 |       | 33265   (2)| 00:06:40 |
|*  3 |    HASH JOIN             |           |  1404K|   121M|    19M| 33178   (1)| 00:06:39 |
|*  4 |     HASH JOIN            |           |   307K|    16M|  8712K| 23708   (1)| 00:04:45 |
|   5 |      VIEW                | VW_SQ_1   |   307K|  5104K|       | 13493   (1)| 00:02:42 |
|   6 |       HASH GROUP BY      |           |   307K|    13M|   191M| 13493   (1)| 00:02:42 |
|*  7 |        INDEX FULL SCAN   | AUSU_PK   |  2809K|   125M|       | 13493   (1)| 00:02:42 |
|*  8 |      INDEX FAST FULL SCAN| AUSU_PK   |  2809K|   104M|       |  2977   (2)| 00:00:36 |
|*  9 |     TABLE ACCESS FULL    | AU_SUBTYP |  1404K|    46M|       |  5336   (2)| 00:01:05 |
Predicate Information (identified by operation id):
   1 - filter("AU_SUBTYP1"."CREATE_TS"=MAX("AU_SUBTYP2"."CREATE_TS"))
   3 - access("AU_SUBTYP2"."AU_ID_K"="AU_SUBTYP1"."AU_ID_K")
   4 - access("AU_SUBTYP2"."EFF_DTE"="VW_COL_1" AND "AU_ID_K"="AU_SUBTYP2"."AU_ID_K")
   7 - access("AU_SUBTYP3"."EFF_DTE"<=TO_DATE(' 2012-12-31 00:00:00', 'syyyy-mm-dd
              hh24:mi:ss') AND "AU_SUBTYP3"."CREATE_TS"<TIMESTAMP' 2013-01-01 00:00:00')
       filter("AU_SUBTYP3"."CREATE_TS"<TIMESTAMP' 2013-01-01 00:00:00' AND
              "AU_SUBTYP3"."EFF_DTE"<=TO_DATE(' 2012-12-31 00:00:00', 'syyyy-mm-dd hh24:mi:ss'))
   8 - filter("AU_SUBTYP2"."CREATE_TS"<TIMESTAMP' 2013-01-01 00:00:00')
   9 - filter("AU_SUBTYP1"."EXISTS_FLG"='Y')Code 2:
I already raised a thread a week back and Dom suggested the following query, it is cost effective but the performance is same and used the same amount of Temp tablespace
select au_id_k,pgm_struct_id_k from (
SELECT au_id_k
      ,      pgm_struct_id_k
      ,      ROW_NUMBER() OVER (PARTITION BY au_id_k ORDER BY eff_dte DESC, create_ts DESC) rn,
      create_ts, eff_dte,exists_flg
      FROM   au_subtyp
      WHERE  create_ts < TO_DATE('2013-01-01','YYYY-MM-DD')
      AND    eff_dte  <= TO_DATE('2012-12-31','YYYY-MM-DD') 
      ) d  where rn =1   and exists_flg = 'Y'
--Explain Plan
Plan hash value: 4039566059
| Id  | Operation                | Name      | Rows  | Bytes |TempSpc| Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT         |           |  2809K|   168M|       | 40034   (1)| 00:08:01 |
|*  1 |  VIEW                    |           |  2809K|   168M|       | 40034   (1)| 00:08:01 |
|*  2 |   WINDOW SORT PUSHED RANK|           |  2809K|   133M|   365M| 40034   (1)| 00:08:01 |
|*  3 |    TABLE ACCESS FULL     | AU_SUBTYP |  2809K|   133M|       |  5345   (2)| 00:01:05 |
Predicate Information (identified by operation id):
   1 - filter("RN"=1 AND "EXISTS_FLG"='Y')
   2 - filter(ROW_NUMBER() OVER ( PARTITION BY "AU_ID_K" ORDER BY
              INTERNAL_FUNCTION("EFF_DTE") DESC ,INTERNAL_FUNCTION("CREATE_TS") DESC )<=1)
   3 - filter("CREATE_TS"<TIMESTAMP' 2013-01-01 00:00:00' AND "EFF_DTE"<=TO_DATE('
              2012-12-31 00:00:00', 'syyyy-mm-dd hh24:mi:ss'))Thanks,
Vijay

Answer 1

Hi Justin,
Thanks for your reply. I am running this on our Test environment as I don't want to run this on Production environment now. The test environment holds 2809605 records (2 Million).
The query output count is 281699 (2 Hundred Thousand) records and the selectivity is 0.099. The Distinct values of create_ts, eff_dte, and exists_flg is 2808905 records. I am sure the index scan is not going to help out much as you said.
The core problem is both queries are using lot of Temp tablespace. When we use this query to join the tables, the other table has the same design as below so the temp tablespace grows bigger.
Both the production and test environment are 3 Node RAC.
First Query...
CPU used by this session     4740
CPU used when call started     4740
Cached Commit SCN referenced     21393
DB time     4745
OS Involuntary context switches     467
OS Page reclaims     64253
OS System time used     26
OS User time used     4562
OS Voluntary context switches     16
SQL*Net roundtrips to/from client     9
bytes received via SQL*Net from client     2487
bytes sent via SQL*Net to client     15830
calls to get snapshot scn: kcmgss     37
consistent gets     52162
consistent gets - examination     2
consistent gets from cache     52162
enqueue releases     19
enqueue requests     19
enqueue waits     1
execute count     2
ges messages sent     1
global enqueue gets sync     19
global enqueue releases     19
index fast full scans (full)     1
index scans kdiixs1     1
no work - consistent read gets     52125
opened cursors cumulative     2
parse count (hard)     1
parse count (total)     2
parse time cpu     1
parse time elapsed     1
physical write IO requests     69
physical write bytes     17522688
physical write total IO requests     69
physical write total bytes     17522688
physical write total multi block requests     69
physical writes     2139
physical writes direct     2139
physical writes direct temporary tablespace     2139
physical writes non checkpoint     2139
recursive calls     19
recursive cpu usage     1
session cursor cache hits     1
session logical reads     52162
sorts (memory)     2
sorts (rows)     760
table scan blocks gotten     23856
table scan rows gotten     2809607
table scans (short tables)     1
user I/O wait time     1
user calls     11
workarea executions - onepass     1
workarea executions - optimal     9
Second Query
CPU used by this session     1197
CPU used when call started     1197
Cached Commit SCN referenced     21393
DB time     1201
OS Involuntary context switches     8684
OS Page reclaims     21769
OS System time used     14
OS User time used     1183
OS Voluntary context switches     50
SQL*Net roundtrips to/from client     9
bytes received via SQL*Net from client     767
bytes sent via SQL*Net to client     15745
calls to get snapshot scn: kcmgss     17
consistent gets     23871
consistent gets from cache     23871
db block gets     16
db block gets from cache     16
enqueue releases     25
enqueue requests     25
enqueue waits     1
execute count     2
free buffer requested     1
ges messages sent     1
global enqueue get time     1
global enqueue gets sync     25
global enqueue releases     25
no work - consistent read gets     23856
opened cursors cumulative     2
parse count (hard)     1
parse count (total)     2
parse time elapsed     1
physical read IO requests     27
physical read bytes     6635520
physical read total IO requests     27
physical read total bytes     6635520
physical read total multi block requests     27
physical reads     810
physical reads direct     810
physical reads direct temporary tablespace     810
physical write IO requests     117
physical write bytes     24584192
physical write total IO requests     117
physical write total bytes     24584192
physical write total multi block requests     117
physical writes     3001
physical writes direct     3001
physical writes direct temporary tablespace     3001
physical writes non checkpoint     3001
recursive calls     25
session cursor cache hits     1
session logical reads     23887
sorts (disk)     1
sorts (memory)     2
sorts (rows)     2810365
table scan blocks gotten     23856
table scan rows gotten     2809607
table scans (short tables)     1
user I/O wait time     2
user calls     11
workarea executions - onepass     1
workarea executions - optimal     5Thanks,
Vijay
Edited by: Vijayaraghavan Krishnan on Nov 28, 2012 11:17 AM
Edited by: Vijayaraghavan Krishnan on Nov 28, 2012 11:19 AM