cardinality/rows column in the explain plan
- From: ryan_gaffuri@xxxxxxxxxxx
- To: oracle-l@xxxxxxxxxxxxx
- Date: Tue, 24 Oct 2006 15:21:14 +0000
I am looking at an explain plan with set autotrace on.
Table C has 53,000 rows. When I query dba_tables.num_rows it states that there
are 53,000 rows. How can I have 'rows' of 1634 on a full table scan? Shouldn't
it be all the rows in the table since Oracle is doing a full table scan?
I get teh same number when I look at the cardinality column in the 'explain
plan for'. I had though that Oracle got the rows for a full table scan from
dba_tables.num_rows? I guess not.
-----------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows |
Bytes | Cost (%CPU)| Pstart| Pstop |
-----------------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 |
60 | 31780 (1)| | |
| 1 | SORT AGGREGATE | | 1 |
60 | | | |
| 2 | TABLE ACCESS BY LOCAL INDEX ROWID| TABLE A | 1 |
22 | 4 (0)| | |
| 3 | NESTED LOOPS | | 2986 |
174K| 31780 (1)| | |
| 4 | HASH JOIN | | 9506 |
352K| 3176 (4)| | |
| 5 | TABLE ACCESS FULL | TABLE B | 211 |
3587 | 229 (6)| | |
| 6 | TABLE ACCESS FULL | TABLE C | 1634 |
34314 | 2947 (4)| | |
| 7 | PARTITION RANGE ITERATOR | | 1 |
| 3 (0)| KEY | KEY |
| 8 | INDEX RANGE SCAN | TABLE_A_IDX01 | 1 |
| 3 (0)| KEY | KEY |
-----------------------------------------------------------------------------------------------------------------
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