Query with non partition key in partitioning table

Question

i compare query select with non-partition key condition in table partition with 3, 4 and 6 partition.
time execution for 3 partition faster then 4 partition, time execution for 4 partition faster than 6 partition.
i know processing query select is selection all partition, but i don't know what make time execution different between 3, 4 and 6 partition??
whether the transfer from one partition to another partition takes time?
this example sql trace query select for 3,4 and 6 partition
3 partition
SELECT *
FROM
EQU_PARAM_MONITORINGHASH WHERE TO_CHAR(time_stamp,'mm/yy')=('02/09')
call          cpu    elapsed       disk        rows
Parse        0.00       0.00          0           0
Execute      0.00       0.00          0           0
Fetch        5.70       7.57      25291     1157583
total        5.70       7.57      25291     1157583
Parsing user id: 61  (SKENARIO1)
Rows     Execution Plan
      0  SELECT STATEMENT   MODE: ALL_ROWS
      0   PARTITION HASH (ALL) PARTITION: START=1 STOP=3
      0    TABLE ACCESS   MODE: ANALYZED (FULL) OF
               'EQU_PARAM_MONITORINGHASH' (TABLE) PARTITION: START=1 STOP=34 partition
SELECT *
FROM
EQU_PARAM_MONITORINGHASH WHERE TO_CHAR(time_stamp,'mm/yy')=('02/09')
call          cpu    elapsed       disk        rows
Parse        0.00       0.00          0           0
Execute      0.00       0.00          0           0
Fetch        5.46       8.03      25126     1157583
total        5.46       8.03      25126     1157583
Parsing user id: 62  (SKENARIO2)
Rows     Execution Plan
      0  SELECT STATEMENT   MODE: ALL_ROWS
      0   PARTITION HASH (ALL) PARTITION: START=1 STOP=4
      0    TABLE ACCESS   MODE: ANALYZED (FULL) OF
               'EQU_PARAM_MONITORINGHASH' (TABLE) PARTITION: START=1 STOP=46 partition
SELECT *
FROM
EQU_PARAM_MONITORINGHASH WHERE TO_CHAR(time_stamp,'mm/yy')=('02/09')
call          cpu    elapsed       disk        rows
Parse        0.00       0.00          0           0
Execute      0.00       0.00          0           0
Fetch        5.73       9.13      25190     1157583
total        5.73       9.13      25190     1157583
Parsing user id: 63  (SKENARIO3)
Rows     Execution Plan
      0  SELECT STATEMENT   MODE: ALL_ROWS
      0   PARTITION HASH (ALL) PARTITION: START=1 STOP=6
      0    TABLE ACCESS   MODE: ANALYZED (FULL) OF
               'EQU_PARAM_MONITORINGHASH' (TABLE) PARTITION: START=1 STOP=6thanks
best regards
eko

Answer 1

ekopur wrote:
i compare query select with non-partition key condition in table partition with 3, 4 and 6 partition.
time execution for 3 partition faster then 4 partition, time execution for 4 partition faster than 6 partition.
i know processing query select is selection all partition, but i don't know what make time execution different between 3, 4 and 6 partition??
whether the transfer from one partition to another partition takes time?
this example sql trace query select for 3,4 and 6 partition
3 partition
SELECT *
FROM
EQU_PARAM_MONITORINGHASH WHERE TO_CHAR(time_stamp,'mm/yy')=('02/09')
call          cpu    elapsed       disk        rows
Parse        0.00       0.00          0           0
Execute      0.00       0.00          0           0
Fetch        5.70       7.57      25291     1157583
total        5.70       7.57      25291     1157583
Parsing user id: 61  (SKENARIO1)
Rows     Execution Plan
0  SELECT STATEMENT   MODE: ALL_ROWS
0   PARTITION HASH (ALL) PARTITION: START=1 STOP=3
0    TABLE ACCESS   MODE: ANALYZED (FULL) OF
'EQU_PARAM_MONITORINGHASH' (TABLE) PARTITION: START=1 STOP=34 partition
SELECT *
FROM
EQU_PARAM_MONITORINGHASH WHERE TO_CHAR(time_stamp,'mm/yy')=('02/09')
call          cpu    elapsed       disk        rows
Parse        0.00       0.00          0           0
Execute      0.00       0.00          0           0
Fetch        5.46       8.03      25126     1157583
total        5.46       8.03      25126     1157583
Parsing user id: 62  (SKENARIO2)
Rows     Execution Plan
0  SELECT STATEMENT   MODE: ALL_ROWS
0   PARTITION HASH (ALL) PARTITION: START=1 STOP=4
0    TABLE ACCESS   MODE: ANALYZED (FULL) OF
'EQU_PARAM_MONITORINGHASH' (TABLE) PARTITION: START=1 STOP=46 partition
SELECT *
FROM
EQU_PARAM_MONITORINGHASH WHERE TO_CHAR(time_stamp,'mm/yy')=('02/09')
call          cpu    elapsed       disk        rows
Parse        0.00       0.00          0           0
Execute      0.00       0.00          0           0
Fetch        5.73       9.13      25190     1157583
total        5.73       9.13      25190     1157583
Parsing user id: 63  (SKENARIO3)
Rows     Execution Plan
0  SELECT STATEMENT   MODE: ALL_ROWS
0   PARTITION HASH (ALL) PARTITION: START=1 STOP=6
0    TABLE ACCESS   MODE: ANALYZED (FULL) OF
'EQU_PARAM_MONITORINGHASH' (TABLE) PARTITION: START=1 STOP=6
I'm assuming you recreated the table a couple of times with different numbers of hash partitions. (Tip: always use a power of two for the number of hash partitions - it keeps them all around the same size if you are using the feature on an appropriate data set.)
There isn't really enough difference in time within the database to make any sensible comment about the difference in times. I note that you have also edited out the fetch count for the 1.1 million rows fetched, and have not captured (or perhaps just not printed) the wait times, so we don't know where you spent the time inside and outside the database.
For all we can tell, the difference you are worried about might simply be network time on the fetch calls, and have nothing to do with the extract you've published.
Regards
Jonathan Lewis