Can I write this query in another way (prefferably in optimized manner)

Question

My database version._
[oracle@localhost ~]$ uname -a
Linux localhost.localdomain 2.6.18-194.17.1.0.1.el5 #1 SMP Wed Sep 29 15:40:03 EDT 2010 i686 i686 i386 GNU/Linux
[oracle@localhost ~]$ sqlplus / as sysdba
SQL*Plus: Release 11.2.0.2.0 Production on Fri Aug 12 04:44:21 2011
Copyright (c) 1982, 2010, Oracle.  All rights reserved.
Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.2.0 - Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL> SELECT * FROM v$version;
BANNER
Oracle Database 11g Enterprise Edition Release 11.2.0.2.0 - Production
PL/SQL Release 11.2.0.2.0 - Production
CORE    11.2.0.2.0      Production
TNS for Linux: Version 11.2.0.2.0 - Production
NLSRTL Version 11.2.0.2.0 - Production
SQL>
Introduction to data and logic._
I have on table called inv_leg_dummy. The main columns to consider is arrival_airport and departure_airport. Say a flight starts from kolkata (KOL) -> Goes to Dellhi (DEL) -> Goes to Hongkong (HKG) -> Goes to Tiwan (TPE). So in total KOL -> DEL -> HKG -> TPE
Data will be like:
Arrival Airport         Departure Airport
HKG                       TPE
KOL                       DEL
DEL                       HKGPlease note that the order is not as expected, that means the flight starts from kolkata can not be determined straight way from the arrangment or any kind of flag.
The main logic is, I first take Arrival Airport HKG and see if any Departure Airport exists as HKG, then I take the next KOL and see if any Departure Airport exists as KOL. You can notice KOL is only present as arrival airport, So, This is the first leg of the flight journey. By the same logic, I can determine next leg, that is DEL (because flight goes from KOL to DEL)...
I need output like :
ARRIVAL_AIRPORT     DEPARTURE_AIRPORT     SEQ
HKG                  TPE              1
DEL                  HKG              2
KOL                  DEL              3
                  KOL              4So, The starting point KOL has heighest sequence (arrival is null), then KOL to DEL, DEL to HKG and finally HKG to TPE (sequence 1). The sequence may look like reverse order.
Create Table and Insert Scripts._
CREATE TABLE inv_leg_dummy
  carrier              VARCHAR2(3) not null,
  flt_num              VARCHAR2(4) not null,
  flt_num_suffix       VARCHAR2(1) default ' ' not null,
  flt_date             DATE not null,
  arrival_airport              VARCHAR2(5),
  departure_airport              VARCHAR2(5) not null
alter table inv_leg_dummy
  add constraint XPKINV_LEG primary key (carrier,flt_num,flt_num_suffix,flt_date,departure_airport);
TRUNCATE table inv_leg_dummy; 
INSERT INTO inv_leg_dummy VALUES ('KA',1,' ',to_date('05/23/2011','mm/dd/rrrr'),'HKG','TPE');
INSERT INTO inv_leg_dummy VALUES ('KA',1,' ',to_date('05/23/2011','mm/dd/rrrr'),'KOL','DEL');
INSERT INTO inv_leg_dummy VALUES ('KA',1,' ',to_date('05/23/2011','mm/dd/rrrr'),'DEL','HKG');
INSERT INTO inv_leg_dummy VALUES ('CX',1,' ',to_date('05/22/2011','mm/dd/rrrr'),'HKG','BNE');
INSERT INTO inv_leg_dummy VALUES ('CX',1,' ',to_date('05/22/2011','mm/dd/rrrr'),'BNE','CNS');
Now, it time to show you, What I have done!_
SQL> ed
Wrote file afiedt.buf
  1  SELECT Carrier,
  2         Flt_Num,
  3         Flt_Date,
  4         Flt_num_Suffix,
  5         arrival_airport,
  6         departure_airport,
  7         RANK() OVER(partition by Carrier, Flt_Num, Flt_Date, Flt_num_Suffix ORDER BY Carrier, Flt_Num, Flt_Date, Flt_num_Suffix, SEQ ASC NULLS LAST) SEQ,
  8         /* Fetching Maximum leg Seq No excluding Dummy Leg*/
  9         max(seq) over(partition by carrier, flt_num, flt_date, flt_num_suffix order by carrier, flt_num, flt_date, flt_num_suffix) max_seq
10    FROM (SELECT k.Carrier,
11                 k.Flt_Num,
12                 k.Flt_Date,
13                 k.Flt_num_Suffix,
14                 k.departure_airport,
15                 k.arrival_airport,
16                 level seq
17            FROM (SELECT
18                   l.Carrier,
19                   l.Flt_Num,
20                   l.Flt_Date,
21                   l.Flt_num_Suffix,
22                   l.departure_airport,
23                   l.arrival_airport
24                    FROM inv_leg_dummy l) k
25           START WITH k.departure_airport = case when
26           (select count(*)
27                         FROM inv_leg_dummy ifl
28                        WHERE ifl.arrival_airport = k.departure_airport
29                          AND ifl.flt_num = k.flt_num
30                          AND ifl.carrier = k.carrier
31                          AND ifl.flt_num_suffix = k.Flt_num_Suffix) = 0 then k.departure_airport end
32          CONNECT BY prior k.arrival_airport = k.departure_airport
33                 AND prior k.carrier = k.carrier
34                 AND prior k.flt_num = k.flt_num
35                 AND prior TRUNC(k.flt_date) =
36                                                TRUNC(k.flt_date)
37          UNION ALL
38          /* Fetching Dummy Last Leg Information for Leg_Seq No*/
39          SELECT ofl.Carrier,
40                 ofl.Flt_Num,
41                 ofl.Flt_Date,
42                 ofl.Flt_num_Suffix,
43                 ofl.arrival_airport as departure_airport,
44                 NULL arrival_airport,
45                 NULL seq
46            FROM inv_leg_dummy ofl
47           where NOT EXISTS (SELECT 1
48                    FROM inv_leg_dummy ifl
49                   WHERE ofl.arrival_airport = ifl.departure_airport
50                     AND ifl.flt_num = ofl.flt_num
51                     AND ifl.carrier = ofl.carrier
52                     AND ifl.flt_num_suffix =ofl.Flt_num_Suffix))
53*  ORDER BY 1, 2, 3, 4,7
SQL> /
CAR FLT_ FLT_DATE  F ARRIV DEPAR        SEQ    MAX_SEQ
CX  1    22-MAY-11   BNE   CNS            1          2
CX  1    22-MAY-11   HKG   BNE            2          2
CX  1    22-MAY-11         HKG            3          2
KA  1    23-MAY-11   HKG   TPE            1          3
KA  1    23-MAY-11   DEL   HKG            2          3
KA  1    23-MAY-11   KOL   DEL            3          3
KA  1    23-MAY-11         KOL            4          3
7 rows selected.
SQL> The code is giving the right output, But I feel, I have done it in a hard way. Is there any easier/optimized approach to solve the problem ?

Answer 1

Hello
I thought I'd run run all 3 methods twice with autotrace to get an overview of the execution plans and basic performance metrics. The results are interesting.
OPs method
SQL> set autot on
SQL> SELECT Carrier,
  2           Flt_Num,
  3           Flt_Date,
  4           Flt_num_Suffix,
  5           arrival_airport,
  6           departure_airport,
  7           RANK() OVER(partition by Carrier, Flt_Num, Flt_Date, Flt_num_Suffix ORDER BY Carrier, Flt_Num,
53   ORDER BY 1, 2, 3, 4,7
54  /
CAR FLT_ FLT_DATE  F ARRIV DEPAR        SEQ    MAX_SEQ
CX  1    22-MAY-11   BNE   CNS            1          2
CX  1    22-MAY-11   HKG   BNE            2          2
CX  1    22-MAY-11         HKG            3          2
KA  1    23-MAY-11   HKG   TPE            1          3
KA  1    23-MAY-11   DEL   HKG            2          3
KA  1    23-MAY-11   KOL   DEL            3          3
KA  1    23-MAY-11         KOL            4          3
7 rows selected.
Execution Plan
Plan hash value: 3680289985
| Id  | Operation                         | Name          |
|   0 | SELECT STATEMENT                  |               |
|   1 |  WINDOW SORT                      |               |
|   2 |   VIEW                            |               |
|   3 |    UNION-ALL                      |               |
|*  4 |     CONNECT BY WITH FILTERING     |               |
|*  5 |      FILTER                       |               |
|*  6 |       TABLE ACCESS FULL           | INV_LEG_DUMMY |
|   7 |       SORT AGGREGATE              |               |
|*  8 |        TABLE ACCESS BY INDEX ROWID| INV_LEG_DUMMY |
|*  9 |         INDEX RANGE SCAN          | XPKINV_LEG    |
|  10 |      NESTED LOOPS                 |               |
|  11 |       CONNECT BY PUMP             |               |
|  12 |       TABLE ACCESS BY INDEX ROWID | INV_LEG_DUMMY |
|* 13 |        INDEX RANGE SCAN           | XPKINV_LEG    |
|* 14 |     FILTER                        |               |
|  15 |      TABLE ACCESS FULL            | INV_LEG_DUMMY |
|* 16 |      INDEX RANGE SCAN             | XPKINV_LEG    |
Predicate Information (identified by operation id):
   4 - access("L"."DEPARTURE_AIRPORT"=PRIOR "L"."ARRIVAL_AIRPORT" AND
              "L"."CARRIER"=PRIOR "L"."CARRIER" AND "L"."FLT_NUM"=PRIOR "L"."FLT
_NUM"
              AND INTERNAL_FUNCTION(PRIOR TRUNC(INTERNAL_FUNCTION("L"."FLT_DATE"
)))=TR
              UNC(INTERNAL_FUNCTION("L"."FLT_DATE")))
   5 - filter("L"."DEPARTURE_AIRPORT"=CASE  WHEN ( (SELECT COUNT(*)
              FROM "INV_LEG_DUMMY" "IFL" WHERE "IFL"."FLT_NUM_SUFFIX"=:B1 AND
              "IFL"."FLT_NUM"=:B2 AND "IFL"."CARRIER"=:B3 AND
              "IFL"."ARRIVAL_AIRPORT"=:B4)=0) THEN "L"."DEPARTURE_AIRPORT" END )
   6 - access("L"."CARRIER"=PRIOR "L"."CARRIER")
   8 - filter("IFL"."ARRIVAL_AIRPORT"=:B1)
   9 - access("IFL"."CARRIER"=:B1 AND "IFL"."FLT_NUM"=:B2 AND
              "IFL"."FLT_NUM_SUFFIX"=:B3)
  13 - access("L"."CARRIER"=PRIOR "L"."CARRIER" AND "L"."FLT_NUM"=PRIOR
              "L"."FLT_NUM" AND "L"."DEPARTURE_AIRPORT"=PRIOR "L"."ARRIVAL_AIRPO
RT")
       filter("L"."DEPARTURE_AIRPORT"=PRIOR "L"."ARRIVAL_AIRPORT" AND
              INTERNAL_FUNCTION(PRIOR TRUNC(INTERNAL_FUNCTION("L"."FLT_DATE")))=
TRUNC(
              INTERNAL_FUNCTION("L"."FLT_DATE")))
  14 - filter( NOT EXISTS (SELECT 0 FROM "INV_LEG_DUMMY" "IFL" WHERE
              "IFL"."FLT_NUM_SUFFIX"=:B1 AND "IFL"."FLT_NUM"=:B2 AND
              "IFL"."CARRIER"=:B3 AND "IFL"."DEPARTURE_AIRPORT"=:B4))
  16 - access("IFL"."CARRIER"=:B1 AND "IFL"."FLT_NUM"=:B2 AND
              "IFL"."FLT_NUM_SUFFIX"=:B3 AND "IFL"."DEPARTURE_AIRPORT"=:B4)
       filter("IFL"."DEPARTURE_AIRPORT"=:B1)
Note
   - rule based optimizer used (consider using cbo)
Statistics
          1  recursive calls
          0  db block gets
         33  consistent gets
          0  physical reads
          0  redo size
        877  bytes sent via SQL*Net to client
        886  bytes received via SQL*Net from client
          2  SQL*Net roundtrips to/from client
          6  sorts (memory)
          0  sorts (disk)
          7  rows processed
SQL> /
CAR FLT_ FLT_DATE  F ARRIV DEPAR        SEQ    MAX_SEQ
CX  1    22-MAY-11   BNE   CNS            1          2
CX  1    22-MAY-11   HKG   BNE            2          2
CX  1    22-MAY-11         HKG            3          2
KA  1    23-MAY-11   HKG   TPE            1          3
KA  1    23-MAY-11   DEL   HKG            2          3
KA  1    23-MAY-11   KOL   DEL            3          3
KA  1    23-MAY-11         KOL            4          3
7 rows selected.
Execution Plan
Plan hash value: 3680289985
| Id  | Operation                         | Name          |
|   0 | SELECT STATEMENT                  |               |
|   1 |  WINDOW SORT                      |               |
|   2 |   VIEW                            |               |
|   3 |    UNION-ALL                      |               |
|*  4 |     CONNECT BY WITH FILTERING     |               |
|*  5 |      FILTER                       |               |
|*  6 |       TABLE ACCESS FULL           | INV_LEG_DUMMY |
|   7 |       SORT AGGREGATE              |               |
|*  8 |        TABLE ACCESS BY INDEX ROWID| INV_LEG_DUMMY |
|*  9 |         INDEX RANGE SCAN          | XPKINV_LEG    |
|  10 |      NESTED LOOPS                 |               |
|  11 |       CONNECT BY PUMP             |               |
|  12 |       TABLE ACCESS BY INDEX ROWID | INV_LEG_DUMMY |
|* 13 |        INDEX RANGE SCAN           | XPKINV_LEG    |
|* 14 |     FILTER                        |               |
|  15 |      TABLE ACCESS FULL            | INV_LEG_DUMMY |
|* 16 |      INDEX RANGE SCAN             | XPKINV_LEG    |
Predicate Information (identified by operation id):
   4 - access("L"."DEPARTURE_AIRPORT"=PRIOR "L"."ARRIVAL_AIRPORT" AND
              "L"."CARRIER"=PRIOR "L"."CARRIER" AND "L"."FLT_NUM"=PRIOR "L"."FLT
_NUM"
              AND INTERNAL_FUNCTION(PRIOR TRUNC(INTERNAL_FUNCTION("L"."FLT_DATE"
)))=TR
              UNC(INTERNAL_FUNCTION("L"."FLT_DATE")))
   5 - filter("L"."DEPARTURE_AIRPORT"=CASE  WHEN ( (SELECT COUNT(*)
              FROM "INV_LEG_DUMMY" "IFL" WHERE "IFL"."FLT_NUM_SUFFIX"=:B1 AND
              "IFL"."FLT_NUM"=:B2 AND "IFL"."CARRIER"=:B3 AND
              "IFL"."ARRIVAL_AIRPORT"=:B4)=0) THEN "L"."DEPARTURE_AIRPORT" END )
   6 - access("L"."CARRIER"=PRIOR "L"."CARRIER")
   8 - filter("IFL"."ARRIVAL_AIRPORT"=:B1)
   9 - access("IFL"."CARRIER"=:B1 AND "IFL"."FLT_NUM"=:B2 AND
              "IFL"."FLT_NUM_SUFFIX"=:B3)
  13 - access("L"."CARRIER"=PRIOR "L"."CARRIER" AND "L"."FLT_NUM"=PRIOR
              "L"."FLT_NUM" AND "L"."DEPARTURE_AIRPORT"=PRIOR "L"."ARRIVAL_AIRPO
RT")
       filter("L"."DEPARTURE_AIRPORT"=PRIOR "L"."ARRIVAL_AIRPORT" AND
              INTERNAL_FUNCTION(PRIOR TRUNC(INTERNAL_FUNCTION("L"."FLT_DATE")))=
TRUNC(
              INTERNAL_FUNCTION("L"."FLT_DATE")))
  14 - filter( NOT EXISTS (SELECT 0 FROM "INV_LEG_DUMMY" "IFL" WHERE
              "IFL"."FLT_NUM_SUFFIX"=:B1 AND "IFL"."FLT_NUM"=:B2 AND
              "IFL"."CARRIER"=:B3 AND "IFL"."DEPARTURE_AIRPORT"=:B4))
  16 - access("IFL"."CARRIER"=:B1 AND "IFL"."FLT_NUM"=:B2 AND
              "IFL"."FLT_NUM_SUFFIX"=:B3 AND "IFL"."DEPARTURE_AIRPORT"=:B4)
       filter("IFL"."DEPARTURE_AIRPORT"=:B1)
Note
   - rule based optimizer used (consider using cbo)
Statistics
          0  recursive calls
          0  db block gets
         33  consistent gets
          0  physical reads
          0  redo size
        877  bytes sent via SQL*Net to client
        886  bytes received via SQL*Net from client
          2  SQL*Net roundtrips to/from client
          6  sorts (memory)
          0  sorts (disk)
          7  rows processedMy method
SQL> SELECT
  2      carrier,
  3      flt_num,
  4      flt_num_suffix,
  5      flt_date,
  6      arrival_airport,
  7      departure_airport,
  8      COUNT(*) OVER(PARTITION BY carrier,
  9                                  flt_num
10                    ) - LEVEL + 1  seq,
11      COUNT(*) OVER(PARTITION BY carrier,
12                                  flt_num
13                    )  - 1        max_seq
57  /
CAR FLT_ F FLT_DATE  ARRIV DEPAR        SEQ    MAX_SEQ
CX  1      22-MAY-11 BNE   CNS            1          2
CX  1      22-MAY-11 HKG   BNE            2          2
CX  1      22-MAY-11       HKG            3          2
KA  1      23-MAY-11 HKG   TPE            1          3
KA  1      23-MAY-11 DEL   HKG            2          3
KA  1      23-MAY-11 KOL   DEL            3          3
KA  1      23-MAY-11       KOL            4          3
7 rows selected.
Execution Plan
Plan hash value: 921778235
| Id  | Operation                                 | Name          |
|   0 | SELECT STATEMENT                          |               |
|   1 |  SORT ORDER BY                            |               |
|   2 |   WINDOW SORT                             |               |
|*  3 |    CONNECT BY NO FILTERING WITH START-WITH|               |
|   4 |     COUNT                                 |               |
|   5 |      VIEW                                 |               |
|   6 |       UNION-ALL                           |               |
|   7 |        TABLE ACCESS FULL                  | INV_LEG_DUMMY |
|*  8 |        FILTER                             |               |
|   9 |         TABLE ACCESS FULL                 | INV_LEG_DUMMY |
|* 10 |         INDEX RANGE SCAN                  | XPKINV_LEG    |
Predicate Information (identified by operation id):
   3 - access("ARRIVAL_AIRPORT"=PRIOR "DEPARTURE_AIRPORT" AND
              "CARRIER"=PRIOR "CARRIER" AND "FLT_NUM"=PRIOR "FLT_NUM" AND
              TRUNC(INTERNAL_FUNCTION("FLT_DATE"))=INTERNAL_FUNCTION(PRIOR
              TRUNC(INTERNAL_FUNCTION("FLT_DATE"))))
       filter("ARRIVAL_AIRPORT" IS NULL)
   8 - filter( NOT EXISTS (SELECT 0 FROM "INV_LEG_DUMMY" "DL" WHERE
              "DL"."FLT_NUM"=:B1 AND "DL"."CARRIER"=:B2 AND
              "DL"."DEPARTURE_AIRPORT"=:B3 AND "DL"."FLT_DATE"=:B4))
  10 - access("DL"."CARRIER"=:B1 AND "DL"."FLT_NUM"=:B2 AND
              "DL"."FLT_DATE"=:B3 AND "DL"."DEPARTURE_AIRPORT"=:B4)
       filter("DL"."DEPARTURE_AIRPORT"=:B1 AND "DL"."FLT_DATE"=:B2)
Note
   - rule based optimizer used (consider using cbo)
Statistics
          1  recursive calls
          0  db block gets
         19  consistent gets
          0  physical reads
          0  redo size
        877  bytes sent via SQL*Net to client
        338  bytes received via SQL*Net from client
          2  SQL*Net roundtrips to/from client
          4  sorts (memory)
          0  sorts (disk)
          7  rows processed
SQL> /
CAR FLT_ F FLT_DATE  ARRIV DEPAR        SEQ    MAX_SEQ
CX  1      22-MAY-11 BNE   CNS            1          2
CX  1      22-MAY-11 HKG   BNE            2          2
CX  1      22-MAY-11       HKG            3          2
KA  1      23-MAY-11 HKG   TPE            1          3
KA  1      23-MAY-11 DEL   HKG            2          3
KA  1      23-MAY-11 KOL   DEL            3          3
KA  1      23-MAY-11       KOL            4          3
7 rows selected.
Execution Plan
Plan hash value: 921778235
| Id  | Operation                                 | Name          |
|   0 | SELECT STATEMENT                          |               |
|   1 |  SORT ORDER BY                            |               |
|   2 |   WINDOW SORT                             |               |
|*  3 |    CONNECT BY NO FILTERING WITH START-WITH|               |
|   4 |     COUNT                                 |               |
|   5 |      VIEW                                 |               |
|   6 |       UNION-ALL                           |               |
|   7 |        TABLE ACCESS FULL                  | INV_LEG_DUMMY |
|*  8 |        FILTER                             |               |
|   9 |         TABLE ACCESS FULL                 | INV_LEG_DUMMY |
|* 10 |         INDEX RANGE SCAN                  | XPKINV_LEG    |
Predicate Information (identified by operation id):
   3 - access("ARRIVAL_AIRPORT"=PRIOR "DEPARTURE_AIRPORT" AND
              "CARRIER"=PRIOR "CARRIER" AND "FLT_NUM"=PRIOR "FLT_NUM" AND
              TRUNC(INTERNAL_FUNCTION("FLT_DATE"))=INTERNAL_FUNCTION(PRIOR
              TRUNC(INTERNAL_FUNCTION("FLT_DATE"))))
       filter("ARRIVAL_AIRPORT" IS NULL)
   8 - filter( NOT EXISTS (SELECT 0 FROM "INV_LEG_DUMMY" "DL" WHERE
              "DL"."FLT_NUM"=:B1 AND "DL"."CARRIER"=:B2 AND
              "DL"."DEPARTURE_AIRPORT"=:B3 AND "DL"."FLT_DATE"=:B4))
  10 - access("DL"."CARRIER"=:B1 AND "DL"."FLT_NUM"=:B2 AND
              "DL"."FLT_DATE"=:B3 AND "DL"."DEPARTURE_AIRPORT"=:B4)
       filter("DL"."DEPARTURE_AIRPORT"=:B1 AND "DL"."FLT_DATE"=:B2)
Note
   - rule based optimizer used (consider using cbo)
Statistics
          0  recursive calls
          0  db block gets
         19  consistent gets
          0  physical reads
          0  redo size
        877  bytes sent via SQL*Net to client
        338  bytes received via SQL*Net from client
          2  SQL*Net roundtrips to/from client
          4  sorts (memory)
          0  sorts (disk)
          7  rows processedSalim Chelabi's method
SQL> WITH t AS
  2       (SELECT     k.*, LEVEL lvl
  3              FROM inv_leg_dummy k
  4        CONNECT BY PRIOR k.arrival_airport = k.departure_airport
  5               AND PRIOR k.flt_date = k.flt_date
  6               AND PRIOR k.carrier = k.carrier
  7               AND PRIOR k.flt_num = k.flt_num)
  8  SELECT   carrier, flt_num, flt_num_suffix, flt_date, arrival_airport,
  9           departure_airport, MAX (lvl) seq,
10           MAX (MAX (lvl)) OVER (PARTITION BY carrier, flt_num, flt_num_suffix)
11                                                                        max_seq
12      FROM t
13  GROUP BY carrier,
14           flt_num,
15           flt_num_suffix,
16           flt_date,
17           arrival_airport,
18           departure_airport
19  UNION ALL
20  SELECT   carrier, flt_num, flt_num_suffix, flt_date, NULL,
21           MAX (arrival_airport), MAX (lvl) + 1 seq, MAX (lvl) max_seq
22      FROM t
23  GROUP BY carrier, flt_num, flt_num_suffix, flt_date
24  ORDER BY 1, 2, 3, seq, arrival_airport NULLS LAST;
CAR FLT_ F FLT_DATE            ARRIV DEPAR        SEQ    MAX_SEQ
CX  1      22/05/2011 00:00:00 BNE   CNS            1          2
CX  1      22/05/2011 00:00:00 HKG   BNE            2          2
CX  1      22/05/2011 00:00:00       HKG            3          2
KA  1      23/05/2011 00:00:00 HKG   TPE            1          3
KA  1      23/05/2011 00:00:00 DEL   HKG            2          3
KA  1      23/05/2011 00:00:00 KOL   DEL            3          3
KA  1      23/05/2011 00:00:00       KOL            4          3
7 rows selected.
Elapsed: 00:00:00.01
Execution Plan
Plan hash value: 2360206974
| Id  | Operation                      | Name                        |
|   0 | SELECT STATEMENT               |                             |
|   1 |  TEMP TABLE TRANSFORMATION     |                             |
|   2 |   LOAD AS SELECT               |                             |
|*  3 |    CONNECT BY WITHOUT FILTERING|                             |
|   4 |     TABLE ACCESS FULL          | INV_LEG_DUMMY               |
|   5 |   SORT ORDER BY                |                             |
|   6 |    UNION-ALL                   |                             |
|   7 |     WINDOW BUFFER              |                             |
|   8 |      SORT GROUP BY             |                             |
|   9 |       VIEW                     |                             |
|  10 |        TABLE ACCESS FULL       | SYS_TEMP_0FD9FE280_59EF9B75 |
|  11 |     SORT GROUP BY              |                             |
|  12 |      VIEW                      |                             |
|  13 |       TABLE ACCESS FULL        | SYS_TEMP_0FD9FE280_59EF9B75 |
Predicate Information (identified by operation id):
   3 - access("K"."DEPARTURE_AIRPORT"=PRIOR "K"."ARRIVAL_AIRPORT" AND
              "K"."FLT_DATE"=PRIOR "K"."FLT_DATE" AND "K"."CARRIER"=PRIOR
              "K"."CARRIER" AND "K"."FLT_NUM"=PRIOR "K"."FLT_NUM")
Note
   - rule based optimizer used (consider using cbo)
Statistics
         57  recursive calls
         10  db block gets
         25  consistent gets
          1  physical reads
       1556  redo size
        877  bytes sent via SQL*Net to client
        338  bytes received via SQL*Net from client
          2  SQL*Net roundtrips to/from client
          5  sorts (memory)
          0  sorts (disk)
          7  rows processed
SQL> /
CAR FLT_ F FLT_DATE            ARRIV DEPAR        SEQ    MAX_SEQ
CX  1      22/05/2011 00:00:00 BNE   CNS            1          2
CX  1      22/05/2011 00:00:00 HKG   BNE            2          2
CX  1      22/05/2011 00:00:00       HKG            3          2
KA  1      23/05/2011 00:00:00 HKG   TPE            1          3
KA  1      23/05/2011 00:00:00 DEL   HKG            2          3
KA  1      23/05/2011 00:00:00 KOL   DEL            3          3
KA  1      23/05/2011 00:00:00       KOL            4          3
7 rows selected.
Elapsed: 00:00:00.01
Execution Plan
Plan hash value: 4065363664
| Id  | Operation                      | Name                        |
|   0 | SELECT STATEMENT               |                             |
|   1 |  TEMP TABLE TRANSFORMATION     |                             |
|   2 |   LOAD AS SELECT               |                             |
|*  3 |    CONNECT BY WITHOUT FILTERING|                             |
|   4 |     TABLE ACCESS FULL          | INV_LEG_DUMMY               |
|   5 |   SORT ORDER BY                |                             |
|   6 |    UNION-ALL                   |                             |
|   7 |     WINDOW BUFFER              |                             |
|   8 |      SORT GROUP BY             |                             |
|   9 |       VIEW                     |                             |
|  10 |        TABLE ACCESS FULL       | SYS_TEMP_0FD9FE281_59EF9B75 |
|  11 |     SORT GROUP BY              |                             |
|  12 |      VIEW                      |                             |
|  13 |       TABLE ACCESS FULL        | SYS_TEMP_0FD9FE281_59EF9B75 |
Predicate Information (identified by operation id):
   3 - access("K"."DEPARTURE_AIRPORT"=PRIOR "K"."ARRIVAL_AIRPORT" AND
              "K"."FLT_DATE"=PRIOR "K"."FLT_DATE" AND "K"."CARRIER"=PRIOR
              "K"."CARRIER" AND "K"."FLT_NUM"=PRIOR "K"."FLT_NUM")
Note
   - rule based optimizer used (consider using cbo)
Statistics
          2  recursive calls
          8  db block gets
         15  consistent gets
          1  physical reads
        604  redo size
        877  bytes sent via SQL*Net to client
        338  bytes received via SQL*Net from client
          2  SQL*Net roundtrips to/from client
          5  sorts (memory)
          0  sorts (disk)
          7  rows processed
SQL> Personally I think Salim's method seems very suiccinct and I had expected there would be more of a difference in terms of performance metrics between it and my attempt but it appears there's not much between the two - although Salim's method is generating redo as a result of the temp table through the subquery factoring. I'd be interested to see the results of a full trace between them.
Either way though, there are two alternatives which seem a fair bit more optimal than the original SQL so it's quids in I guess! :-)
David
Edited by: Bravid on Aug 12, 2011 3:24 PM
Edited by: Bravid on Aug 12, 2011 3:27 PM
Updated the comparison with Salims additional column