Select count(x) on a table with many column numbers?

Question

Hi all,
i have a table with physical data with 850 (!!) colums and
~1 Million rows.
The select count(cycle)from test_table Statement is very, very slow
WHY?
The select count(cycle)from test_table is very fast by e.g 10 Colums. WHY?
What has the number of columns, to do with the SELECT count(cyle).... statement?
create test_table(
cycle number primary key,
stamp date,
sensor 1 number,
sensor 2 number,
sensor_849 number,
sensor_850 number);
on W2K Oracle 9i Enterprise Edition Release 9.2.0.4.0 Production
Can anybody help me?
Many Thanks
Achim

Answer 1

hi lennert, hi all,
many thanks for all the answers. I�m not an Oracle expert.
Sorry for my english.
Hi Lennert,
you are right, what must i do to use the index in the
query? Can you give me a pointer of direction, please?
Many greetings
Achim
select count(*) from w4t.v_tfmc_3_blocktime;
COUNT(*) ==> Table with 3 columns (very fast)
306057
Ausf�hrungsplan
0 SELECT STATEMENT Optimizer=CHOOSE
1 0 SORT (AGGREGATE)
2 1 TABLE ACCESS (FULL) OF 'V_TFMC_3 _BLOCKTIME'    
Statistiken
0 recursive calls
0 db block gets
801 consistent gets
794 physical reads
0 redo size
388 bytes sent via SQL*Net to client
499 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
1 rows processed
select count(*) from w4t.v_tfmc_3_value;
COUNT(*)==> Table with 850 columns (very slow)
64000
Ausf�hrungsplan
0 SELECT STATEMENT Optimizer=CHOOSE
1 0 SORT (AGGREGATE)
2 1 TABLE ACCESS (FULL) OF 'V_TFMC_3 _VALUE'    
Statistiken
1 recursive calls
1 db block gets
48410 consistent gets
38791 physical reads
13068 redo size
387 bytes sent via SQL*Net to client
499 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
1 rows processed