Topic: Performance & Tuning >> performance issue
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| cool_jr.dba |
Posted: Jan 25, 2008 05:30:32 AM |
Total Post: 1
Joined: Jan, 2008
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Hi Tuning gurus
this querry works fine for lesser number of rows
eg :--
where ROWNUM <= 10 )
where rnum >=1;
but takes lot of time as we increase rownum ..
eg :--
where ROWNUM <= 10000 )
where rnum >=9990;
results are posted below
pls suggest me
oracle version -Oracle Database 10g Enterprise Edition
Release 10.2.0.1.0 - Prod
os version red hat enterprise linux ES release 4
also statistics differ when we use table
and its views
results of view v$mail
---------------------------------------
[select * from
( select a.*, ROWNUM rnum from
( SELECT M.MAIL_ID, MAIL_FROM, M.SUBJECT
AS S1,CEIL(M.MAIL_SIZE) AS MAIL_SIZE,
TO_CHAR(MAIL_DATE,'dd Mon yyyy hh:mi:ss
am') AS MAIL_DATE1, M.ATTACHMENT_FLAG,
M.MAIL_TYPE_ID, M.PRIORITY_NO, M.TEXT,
COALESCE(M.MAIL_STATUS_VALUE,0),
0 as email_address,LOWER(M.MAIL_to) as
Mail_to, M.Cc, M.MAIL_DATE AS MAIL_DATE,
lower(subject) as subject,read_ipaddress,
read_datetime,Folder_Id,compose_type,
interc_count,history_id,pined_flag,
rank() over (order by mail_date desc)
as rnk from v$mail M WHERE M.USER_ID=6 AND M.FOLDER_ID =1) a
where ROWNUM <= 10000 )
where rnum >=9990;]
result :
--------------------------------
11 rows selected.
Elapsed: 00:00:03.84
Execution Plan
----------------------------------------------------------
0 SELECT STATEMENT Optimizer=ALL_ROWS (Cost=14735 Card=10000 B
ytes=142430000)
1 0 VIEW (Cost=14735 Card=10000 Bytes=142430000)
2 1 COUNT (STOPKEY)
3 2 VIEW (Cost=14735 Card=14844 Bytes=211230120)
4 3 WINDOW (SORT) (Cost=14735 Card=14844 Bytes=9114216)
5 4 TABLE ACCESS (BY INDEX ROWID) OF 'MAIL' (TABLE) (C
ost=12805 Card=14844 Bytes=9114216)
6 5 INDEX (RANGE SCAN) OF 'FOLDER_USERID' (INDEX) (C
ost=43 Card=14844)
Statistics
----------------------------------------------------------
294 recursive calls
0 db block gets
8715 consistent gets
8669 physical reads
0 redo size
7060 bytes sent via SQL*Net to client
504 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
6 sorts (memory)
0 sorts (disk)
11 rows processed
SQL> select count(*) from v$mail;
Elapsed: 00:00:00.17
Execution Plan
----------------------------------------------------------
0 SELECT STATEMENT Optimizer=ALL_ROWS (Cost=494 Card=1)
1 0 SORT (AGGREGATE)
2 1 INDEX (FAST FULL SCAN) OF 'FOLDER_USERID' (INDEX) (Cost=
494 Card=804661)
Statistics
----------------------------------------------------------
8 recursive calls
0 db block gets
2171 consistent gets
2057 physical reads
260 redo size
352 bytes sent via SQL*Net to client
504 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
1 rows processed
results of original table mail
---------------------------------------
[select * from
( select a.*, ROWNUM rnum from
( SELECT M.MAIL_ID, MAIL_FROM, M.SUBJECT
AS S1,CEIL(M.MAIL_SIZE) AS MAIL_SIZE,
TO_CHAR(MAIL_DATE,'dd Mon yyyy hh:mi:ss
am') AS MAIL_DATE1, M.ATTACHMENT_FLAG,
M.MAIL_TYPE_ID, M.PRIORITY_NO, M.TEXT,
COALESCE(M.MAIL_STATUS_VALUE,0),
0 as email_address,LOWER(M.MAIL_to) as
Mail_to, M.Cc, M.MAIL_DATE AS MAIL_DATE,
lower(subject) as subject,read_ipaddress,
read_datetime,Folder_Id,compose_type,
interc_count,history_id,pined_flag,
rank() over (order by mail_date desc)
as rnk from mail M WHERE M.USER_ID=6 AND M.FOLDER_ID =1) a
where ROWNUM <= 10000 )
where rnum >=9990;]
result :
-----------------------
11 rows selected.
Elapsed: 00:00:03.21
Execution Plan
----------------------------------------------------------
0 SELECT STATEMENT Optimizer=ALL_ROWS (Cost=14735 Card=10000 B
ytes=142430000)
1 0 VIEW (Cost=14735 Card=10000 Bytes=142430000)
2 1 COUNT (STOPKEY)
3 2 VIEW (Cost=14735 Card=14844 Bytes=211230120)
4 3 WINDOW (SORT) (Cost=14735 Card=14844 Bytes=9114216)
5 4 TABLE ACCESS (BY INDEX ROWID) OF 'MAIL' (TABLE) (C
ost=12805 Card=14844 Bytes=9114216)
6 5 INDEX (RANGE SCAN) OF 'FOLDER_USERID' (INDEX) (C
ost=43 Card=14844)
Statistics
----------------------------------------------------------
1 recursive calls
119544 db block gets
8686 consistent gets
8648 physical reads
0 redo size
13510 bytes sent via SQL*Net to client
4084 bytes received via SQL*Net from client
41 SQL*Net roundtrips to/from client
1 sorts (memory)
0 sorts (disk)
11 rows processed
SQL> select count(*) from mail;
Elapsed: 00:00:00.34
Execution Plan
----------------------------------------------------------
0 SELECT STATEMENT Optimizer=ALL_ROWS (Cost=494 Card=1)
1 0 SORT (AGGREGATE)
2 1 INDEX (FAST FULL SCAN) OF 'FOLDER_USERID' (INDEX) (Cost=
494 Card=804661)
Statistics
----------------------------------------------------------
1 recursive calls
0 db block gets
2183 consistent gets
2062 physical reads
72 redo size
352 bytes sent via SQL*Net to client
504 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
1 rows processed
Thanks n regards
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|
 Gitesh |
| Posted: May 14, 2008 04:39:57 AM |  |
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Total Post: 322
Joined: May, 2005
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Did you try to use another HINTS also. Try to put another hint like FIRST_ROWS, FULL table scan etc.
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