Saw somebody bumped one of the many "is select count(1) faster than select count(*)" threads on AskTom .
I believe Tom, but I just had to go and look AGAIN to see if anything changed in 10gR2:
SQL> select count(1) from dbtesting.t;
COUNT(1)
----------
20413
Elapsed: 00:00:00.00
Execution Plan
----------------------------------------------------------
Plan hash value: 2966233522
-------------------------------------------------------------------
| Id | Operation | Name | Rows | Cost (%CPU)| Time |
-------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 59 (2)| 00:00:01 |
| 1 | SORT AGGREGATE | | 1 | | |
| 2 | TABLE ACCESS FULL| T | 20413 | 59 (2)| 00:00:01 |
-------------------------------------------------------------------
Statistics
----------------------------------------------------------
0 recursive calls
0 db block gets
315 consistent gets
0 physical reads
0 redo size
413 bytes sent via SQL*Net to client
381 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
1 rows processed
SQL> select count(*) from dbtesting.t;
COUNT(*)
----------
20413
Elapsed: 00:00:00.00
Execution Plan
----------------------------------------------------------
Plan hash value: 2966233522
-------------------------------------------------------------------
| Id | Operation | Name | Rows | Cost (%CPU)| Time |
-------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 59 (2)| 00:00:01 |
| 1 | SORT AGGREGATE | | 1 | | |
| 2 | TABLE ACCESS FULL| T | 20413 | 59 (2)| 00:00:01 |
-------------------------------------------------------------------
Statistics
----------------------------------------------------------
0 recursive calls
0 db block gets
315 consistent gets
0 physical reads
0 redo size
413 bytes sent via SQL*Net to client
381 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
1 rows processed
SQL> select count(66666) from dbtesting.t;
COUNT(66666)
------------
20413
Elapsed: 00:00:00.00
Execution Plan
----------------------------------------------------------
Plan hash value: 2966233522
-------------------------------------------------------------------
| Id | Operation | Name | Rows | Cost (%CPU)| Time |
-------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 59 (2)| 00:00:01 |
| 1 | SORT AGGREGATE | | 1 | | |
| 2 | TABLE ACCESS FULL| T | 20413 | 59 (2)| 00:00:01 |
-------------------------------------------------------------------
Statistics
----------------------------------------------------------
1 recursive calls
0 db block gets
315 consistent gets
0 physical reads
0 redo size
417 bytes sent via SQL*Net to client
381 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
1 rows processed
SQL> select count(dbms_random.value(1,1000)) from dbtesting.t;
COUNT(DBMS_RANDOM.VALUE(1,1000))
--------------------------------
20413
Elapsed: 00:00:00.17
Execution Plan
----------------------------------------------------------
Plan hash value: 2966233522
-------------------------------------------------------------------
| Id | Operation | Name | Rows | Cost (%CPU)| Time |
-------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 59 (2)| 00:00:01 |
| 1 | SORT AGGREGATE | | 1 | | |
| 2 | TABLE ACCESS FULL| T | 20413 | 59 (2)| 00:00:01 |
-------------------------------------------------------------------
Statistics
----------------------------------------------------------
1 recursive calls
0 db block gets
315 consistent gets
0 physical reads
0 redo size
437 bytes sent via SQL*Net to client
381 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
1 rows processed
SQL> spool off
> >
There, now if somebody somebody is wondering, the argument is solved. They are the same when selecting from a table without a predicate, I even threw in the dbms_random to show any number in the count() is the same.
4 comments:
Not sure I'm convinced - would like to see more data - like 1 million rows?
thanks ur information
it very useful
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