Please help with better sql plan - full test case

Question

Hello,
here is my test case:
SQL> create table ib_auth_devices(dv_id number(12) primary key , dv_cl_id number(12));
Table created.
SQL> create table ib_clients (cl_id number(12) primary key);
Table created.
SQL> alter table ib_auth_devices add constraint fk1 foreign key(dv_cl_id) references ib_clients(cl_id);
Table altered.
SQL> create table ib_tokens (to_dv_id number(12) primary key);
Table created.
SQL> alter table ib_tokens add constraint to_dv_id foreign key(to_dv_id) references ib_auth_devices(dv_id);
Table altered.
SQL> create table ib_auth_cards(au_dv_id number(12) primary key);
Table created.
SQL>  alter table ib_auth_cards add constraint  au_dv_id foreign key(au_dv_id) references ib_auth_devices(dv_id);
Table altered.
SQL> insert into ib_clients values(1);
1 row created.
SQL> insert into ib_clients values(2);
1 row created.
SQL> insert into ib_clients values(3);
1 row created.
SQL> insert into ib_clients values(4);
1 row created.
SQL> insert into ib_clients values(5);
1 row created.
SQL> commit;
Commit complete.
SQL> insert into ib_auth_devices values(1 , 1);
1 row created.
SQL> insert into ib_auth_devices values(2 , 2);
1 row created.
SQL>  insert into ib_auth_devices values(3,3);
1 row created.
SQL> insert into ib_auth_devices values(4,4);
1 row created.
SQL> commit;
Commit complete.
SQL> insert into ib_tokens values(1);
1 row created.
SQL> insert into ib_tokens values(2);
1 row created.
SQL> insert into ib_tokens values(3);
1 row created.
SQL> insert into ib_auth_cards values(1);
1 row created.
SQL> insert into ib_auth_cards values(2);
1 row created.
SQL> commit;
Commit complete.
SQL> select cl_id from ib_clients;
     CL_ID
         1
         2
         3
         4
         5
SQL> select cl_id from ib_clients cli , ib_auth_devices ad
  2  where
  3  cli.cl_id = ad.dv_cl_id;
     CL_ID
         1
         2
         3
         4
SQL> select * from ib_tokens;
  TO_DV_ID
         1
         2
         3
SQL> select * from ib_auth_cards;
  AU_DV_ID
         1
         2
SQL> select * from ib_clients;
     CL_ID
         1
         2
         3
         4
         5
SQL> select * from ib_auth_devices;
     DV_ID   DV_CL_ID
         1          1
         2          2
         3          3
         4          4
SQL> exec dbms_stats.gather_table_stats(user , 'IB_AUTH_DEVICES' , cascade => true);
PL/SQL procedure successfully completed.
SQL> exec dbms_stats.gather_table_stats(user , 'IB_TOKENS'  , cascade => true);
PL/SQL procedure successfully completed.
SQL>  exec dbms_stats.gather_table_stats(user , 'IB_CLIENTS' , cascade => true);
PL/SQL procedure successfully completed.
SQL> exec dbms_stats.gather_table_stats(user , 'IB_AUTH_CARDS' ,  cascade => true);
PL/SQL procedure successfully completed.
SQL> l
  1  select cli.cl_id from ib_clients cli , ib_auth_devices ad,
  2          (select dv_cl_id as cl_id
  3            from ib_auth_cards, ib_auth_devices
  4            where
  5               au_dv_id = dv_id
  6            ) cards,
  7  (       select dv_cl_id as cl_id
  8            from ib_tokens, ib_auth_devices
  9            where
10               to_dv_id = dv_id
11           ) tokens
12  where
13  cli.cl_id = ad.dv_cl_id
14  and cards.cl_id(+)= cli.cl_id
15  and cards.cl_id is null
16  and tokens.cl_id(+)= cli.cl_id
17* and tokens.cl_id is null
SQL> r
  1  select cli.cl_id from ib_clients cli , ib_auth_devices ad,
  2          (select dv_cl_id as cl_id
  3            from ib_auth_cards, ib_auth_devices
  4            where
  5               au_dv_id = dv_id
  6            ) cards,
  7  (       select dv_cl_id as cl_id
  8            from ib_tokens, ib_auth_devices
  9            where
10               to_dv_id = dv_id
11           ) tokens
12  where
13  cli.cl_id = ad.dv_cl_id
14  and cards.cl_id(+)= cli.cl_id
15  and cards.cl_id is null
16  and tokens.cl_id(+)= cli.cl_id
17* and tokens.cl_id is null
Execution Plan
   0      SELECT STATEMENT Optimizer=CHOOSE (Cost=5 Card=4 Bytes=128)
   1    0   FILTER
   2    1     HASH JOIN (OUTER)
   3    2       FILTER
   4    3         HASH JOIN (OUTER)
   5    4           NESTED LOOPS (Cost=1 Card=4 Bytes=24)
   6    5             TABLE ACCESS (FULL) OF 'IB_AUTH_DEVICES' (Cost=1
           Card=4 Bytes=12)
   7    5             INDEX (UNIQUE SCAN) OF 'SYS_C008299' (UNIQUE)
   8    4           VIEW (Cost=1 Card=2 Bytes=26)
   9    8             NESTED LOOPS (Cost=1 Card=2 Bytes=18)
  10    9               TABLE ACCESS (FULL) OF 'IB_AUTH_DEVICES' (Cost
          =1 Card=4 Bytes=24)
  11    9               INDEX (UNIQUE SCAN) OF 'SYS_C008303' (UNIQUE)
  12    2       VIEW (Cost=1 Card=3 Bytes=39)
  13   12         NESTED LOOPS (Cost=1 Card=3 Bytes=27)
  14   13           TABLE ACCESS (FULL) OF 'IB_AUTH_DEVICES' (Cost=1 C
          ard=4 Bytes=24)
  15   13           INDEX (UNIQUE SCAN) OF 'SYS_C008301' (UNIQUE)
Statistics
          0  recursive calls
         12  db block gets
          9  consistent gets
          0  physical reads
          0  redo size
        364  bytes sent via SQL*Net to client
        431  bytes received via SQL*Net from client
          2  SQL*Net roundtrips to/from client
          8  sorts (memory)
          0  sorts (disk)
          1  rows processedAny ideas about rewriting this query to achive better performance ?
Oracle version 8.1.7
Best Regards.
Grzegorz

Answer 1

The answer to this question totally depends on the real volumes you have in your tables. Your test case is probably not showing us these volumes.
However, I see some needless table accesses, so it's probably safe to conclude that this rewrite will speed something up:
SQL> create table ib_auth_devices(dv_id number(12) primary key , dv_cl_id number(12));
Tabel is aangemaakt.
SQL> create table ib_clients (cl_id number(12) primary key);
Tabel is aangemaakt.
SQL> alter table ib_auth_devices add constraint fk1 foreign key(dv_cl_id) references ib_clients(cl_id);
Tabel is gewijzigd.
SQL> create table ib_tokens (to_dv_id number(12) primary key);
Tabel is aangemaakt.
SQL> alter table ib_tokens add constraint to_dv_id foreign key(to_dv_id) references ib_auth_devices(dv_id);
Tabel is gewijzigd.
SQL> create table ib_auth_cards(au_dv_id number(12) primary key);
Tabel is aangemaakt.
SQL> alter table ib_auth_cards add constraint  au_dv_id foreign key(au_dv_id) references ib_auth_devices(dv_id);
Tabel is gewijzigd.
SQL> insert into ib_clients values(1);
1 rij is aangemaakt.
SQL> insert into ib_clients values(2);
1 rij is aangemaakt.
SQL> insert into ib_clients values(3);
1 rij is aangemaakt.
SQL> insert into ib_clients values(4);
1 rij is aangemaakt.
SQL> insert into ib_clients values(5);
1 rij is aangemaakt.
SQL> insert into ib_auth_devices values(1 , 1);
1 rij is aangemaakt.
SQL> insert into ib_auth_devices values(2 , 2);
1 rij is aangemaakt.
SQL> insert into ib_auth_devices values(3,3);
1 rij is aangemaakt.
SQL> insert into ib_auth_devices values(4,4);
1 rij is aangemaakt.
SQL> insert into ib_tokens values(1);
1 rij is aangemaakt.
SQL> insert into ib_tokens values(2);
1 rij is aangemaakt.
SQL> insert into ib_tokens values(3);
1 rij is aangemaakt.
SQL> insert into ib_auth_cards values(1);
1 rij is aangemaakt.
SQL> insert into ib_auth_cards values(2);
1 rij is aangemaakt.
SQL> exec dbms_stats.gather_table_stats(user , 'IB_AUTH_DEVICES' , cascade => true);
PL/SQL-procedure is geslaagd.
SQL> exec dbms_stats.gather_table_stats(user , 'IB_TOKENS'  , cascade => true);
PL/SQL-procedure is geslaagd.
SQL> exec dbms_stats.gather_table_stats(user , 'IB_CLIENTS' , cascade => true);
PL/SQL-procedure is geslaagd.
SQL> exec dbms_stats.gather_table_stats(user , 'IB_AUTH_CARDS' ,  cascade => true);
PL/SQL-procedure is geslaagd.
SQL> set autotrace on explain
SQL> select cli.cl_id
  2    from ib_clients cli
  3       , ib_auth_devices ad
  4       , ( select dv_cl_id as cl_id
  5             from ib_auth_cards
  6                , ib_auth_devices
  7            where au_dv_id = dv_id
  8         ) cards
  9       , ( select dv_cl_id as cl_id
10             from ib_tokens
11                , ib_auth_devices
12            where to_dv_id = dv_id
13         ) tokens
14   where cli.cl_id = ad.dv_cl_id
15     and cards.cl_id(+)= cli.cl_id
16     and cards.cl_id is null
17     and tokens.cl_id(+)= cli.cl_id
18     and tokens.cl_id is null
19  /
                                 CL_ID
                                     4
1 rij is geselecteerd.
Uitvoeringspan
   0      SELECT STATEMENT Optimizer=CHOOSE (Cost=10 Card=4 Bytes=128)
   1    0   FILTER
   2    1     HASH JOIN (OUTER)
   3    2       FILTER
   4    3         HASH JOIN (OUTER)
   5    4           NESTED LOOPS (Cost=4 Card=4 Bytes=24)
   6    5             TABLE ACCESS (FULL) OF 'IB_AUTH_DEVICES' (Cost=3 Card=4 Bytes=12)
   7    5             INDEX (UNIQUE SCAN) OF 'SYS_C001354381' (UNIQUE) (Cost=1 Card=1 Bytes=3)
   8    4           VIEW (Cost=3 Card=2 Bytes=26)
   9    8             NESTED LOOPS (Cost=3 Card=2 Bytes=18)
  10    9               INDEX (FULL SCAN) OF 'SYS_C001354385' (UNIQUE) (Cost=2 Card=2 Bytes=6)
  11    9               TABLE ACCESS (BY INDEX ROWID) OF 'IB_AUTH_DEVICES' (Cost=2 Card=1 Bytes=6)
  12   11                 INDEX (UNIQUE SCAN) OF 'SYS_C001354380' (UNIQUE) (Cost=1 Card=1)
  13    2       VIEW (Cost=3 Card=3 Bytes=39)
  14   13         NESTED LOOPS (Cost=3 Card=3 Bytes=27)
  15   14           INDEX (FULL SCAN) OF 'SYS_C001354383' (UNIQUE) (Cost=2 Card=3 Bytes=9)
  16   14           TABLE ACCESS (BY INDEX ROWID) OF 'IB_AUTH_DEVICES' (Cost=2 Card=1 Bytes=6)
  17   16             INDEX (UNIQUE SCAN) OF 'SYS_C001354380' (UNIQUE) (Cost=1 Card=1)
SQL> select cli.cl_id
  2    from ib_clients cli
  3       , ib_auth_devices ad
  4   where cli.cl_id = ad.dv_cl_id
  5     and not exists
  6         ( select 'dummy'
  7             from ib_auth_cards
  8            where au_dv_id = ad.dv_id
  9         )
10     and not exists
11         ( select 'dummy'
12             from ib_tokens
13            where to_dv_id = ad.dv_id
14         )
15  /
                                 CL_ID
                                     4
1 rij is geselecteerd.
Uitvoeringspan
   0      SELECT STATEMENT Optimizer=CHOOSE (Cost=8 Card=1 Bytes=9)
   1    0   FILTER
   2    1     NESTED LOOPS (Cost=4 Card=1 Bytes=9)
   3    2       TABLE ACCESS (FULL) OF 'IB_AUTH_DEVICES' (Cost=3 Card=1 Bytes=6)
   4    2       INDEX (UNIQUE SCAN) OF 'SYS_C001354381' (UNIQUE) (Cost=1 Card=1 Bytes=3)
   5    1     INDEX (UNIQUE SCAN) OF 'SYS_C001354385' (UNIQUE) (Cost=1 Card=1 Bytes=3)
   6    1     INDEX (UNIQUE SCAN) OF 'SYS_C001354383' (UNIQUE) (Cost=1 Card=1 Bytes=3)Regards,
Rob.