The same query but different plan?

Question

Hi all
I don't understand why the same query but Oracle use different plan
explain plan for select far.id,fab.id
from agent_body fab
INNER JOIN agent_ref far ON (far.bodyid = fab.id)
WHERE fab.id=72449;
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | Pstart| Pstop |
| 0 | SELECT STATEMENT | | 1 | 18 | 2 (0)| 00:00:01 | | |
| 1 | NESTED LOOPS | | 1 | 18 | 2 (0)| 00:00:01 | | |
| 2 | PARTITION HASH SINGLE | | 1 | 6 | 1 (0)| 00:00:01 | 4 | 4 |
|* 3 | INDEX UNIQUE SCAN | PK_AGENT_BODY | 1 | 6 | 1 (0)| 00:00:01 | 4 | 4 |
| 4 | PARTITION HASH ALL | | 1 | 12 | 1 (0)| 00:00:01 | 1 | 4 |
| 5 | TABLE ACCESS BY LOCAL INDEX ROWID| AGENT_REF | 1 | 12 | 1 (0)| 00:00:01 | 1 | 4 |
|* 6 | INDEX RANGE SCAN | IXAGRAD | 1 | | 1 (0)| 00:00:01 | 1 | 4 |
Predicate Information (identified by operation id):
3 - access("FAB"."ID"=72449)
6 - access("FAR"."BODYID"=72449)
AND
explain plan for select far.id,fab.id
from agent_ref far,agent_body fab
where fab.id=far.bodyid and far.id=2219306;
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | Pstart| Pstop |
| 0 | SELECT STATEMENT | | 1 | 18 | 2 (0)| 00:00:01 | | |
| 1 | NESTED LOOPS | | 1 | 18 | 2 (0)| 00:00:01 | | |
| 2 | PARTITION HASH SINGLE | | 1 | 12 | 1 (0)| 00:00:01 | 3 | 3 |
| 3 | TABLE ACCESS BY LOCAL INDEX ROWID| AGENT_REF | 1 | 12 | 1 (0)| 00:00:01 | 3 | 3 |
|* 4 | INDEX UNIQUE SCAN | PK_AGENT_REF | 1 | | 1 (0)| 00:00:01 | 3 | 3 |
| 5 | PARTITION HASH ITERATOR | | 3348K| 19M| 1 (0)| 00:00:01 | KEY | KEY |
|* 6 | INDEX UNIQUE SCAN | PK_AGENT_BODY | 3348K| 19M| 1 (0)| 00:00:01 | KEY | KEY |
Predicate Information (identified by operation id):
4 - access("FAR"."ID"=2219306)
6 - access("FAB"."ID"="FAR"."BODYID")
Can anyone explain to me?
Thanks

Answer 1

user554265 wrote:
Hi all
I don't understand why the same query but Oracle use different plan
explain plan for select far.id,fab.id
from agent_body fab
INNER JOIN agent_ref far ON (far.bodyid = fab.id)
WHERE fab.id=72449;
AND
explain plan for select far.id,fab.id
from agent_ref far,agent_body fab
where fab.id=far.bodyid and far.id=2219306;
Can anyone explain to me?Perhaps this makes a difference...
WHERE fab.id=72449; and
and far.id=2219306; Essentially the two queries ARE different.