Query slow down when added a where clause

I have a procedure that has performance issue, so I copy some of the query and run in the sql plus and try to spot which join cause the problem, but I get a result which I can figuer out why. I have a query which like below:
Select Count(a.ID) From TableA a
-- INNER JOIN other tables
WHERE a.TypeID = 2;
TableA has 140000 records, when the where clause is not added, the count return quite quick, but if I add the where clause, then the query slow down and seems never return so I have to kill my SQL Plus session. TableA has index on TypeID and TypeID is a number type. When TablA has 3000 records, the procedure return very quick, but it slow down and hang there when the TableA contains 140000 records. Any idea why this will slow down the query?
Also, the TypeID is a foreign key to another table (TableAType), so the query above can written as :
Select Count(a.ID) From TableA a
-- INNER JOIN other tables
INNER JOIN TableAType atype ON a.TypeID = atype.ID
WHERE atype.Name = 'typename';
TableAType table is a small table only contains less than 100 records, in this case, would the second query be more efficient to the first query?
Any suggestions are welcome, thanks in advance...
Message was edited by:
user500168

TableA now has 230000 records and 28000 of them has the TypeID 2.
I haven't use the hint yet but thank you for your reply which let me to to run a query to check how many records in TableA has TypeID 2. When I doing this, it seems pretty fast. So I begin with the select count for TableA only and gradually add table to join and seems the query is pretty fast as long as TableA is the fist table to select from.
Before in my query TableA is the second table to join from, there is another table (which is large as well but not as large as TableA) before TableA. So I think this is why it runs slow before. I am not at work yesterday so the query given in my post is based on my roughly memory and I forget to mention another table is joined before TableA, really sorry about that.
I think I learn a lesson here, the largest table need to be in the begining of the select statement...
Thank you very much everyone.

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Hello,
I'm wondering why a small change on a where clause in a query has a dramatic impact on its response time.
Here is the query, with its plan and a few details:
select * from (
SELECT xyz_id, time_oper, ...
     FROM (SELECT
                    d.xyz_id xyz_id,
                    TO_CHAR (di.time_operation, 'DD/MM/YYYY') time_oper,
                    di.time_operation time_operation,
                    UPPER (d.delivery_name || ' ' || d.delivery_firstname) custname,
                    d.ticket_language ticket_language, d.payed,
                    dsum.delivery_mode delivery_mode,
                    d.station_delivery station_delivery,
                    d.total_price total_price, d.crm_cust_id custid,
                    d.bene_cust_id person_id, d.xyz_num, dpe.ers_pnr ers_pnr,
                    d.delivery_name,
                    TO_CHAR (dsum.first_travel_date, 'DD/MM/YYYY') first_traveldate,
                    d.crm_company custtype, UPPER (d.client_name) partyname,
                    getremark(d.xyz_num) remark,
                    d.client_app, di.work_unit, di.account_unit,
                    di.distrib_code,
                    UPPER (d.crm_name || ' ' || d.crm_firstname) crm_custname,
                   getspecialproduct(di.xyz_id) specialproduct
               FROM xyz d, xyz_info di, xyz_pnr_ers dpe, xyz_summary dsum
              WHERE d.cancel_state = 'N'
             -- AND d.payed = 'N'
                AND dsum.delivery_mode NOT IN ('DD')
                AND dsum.payment_method NOT IN ('AC', 'AG')
                AND d.xyz_blocked IS NULL
                AND di.xyz_id = d.xyz_id
                AND di.operation = 'CREATE'
                AND dpe.xyz_id(+) = d.xyz_id
                AND EXISTS (SELECT 1
                              FROM xyz_ticket dt
                             WHERE dt.xyz_id = d.xyz_id)
                AND dsum.xyz_id = di.xyz_id
           ORDER BY di.time_operation DESC)
    WHERE ROWNUM < 1002
) view
WHERE view.DISTRIB_CODE in ('NS') AND view.TIME_OPERATION > TO_DATE('20/5/2013', 'dd/MM/yyyy')
plan with "d.payed = 'N'" (no rows, *extremely* slow):
| Id | Operation                          | Name             | Rows | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT                   |                  | 1001 | 4166K| 39354   (1)| 00:02:59 |
|* 1 | VIEW                              |                  | 1001 | 4166K| 39354   (1)| 00:02:59 |
|* 2 |   COUNT STOPKEY                    |                  |       |       |            |          |
|   3 |    VIEW                            |                  | 1001 | 4166K| 39354   (1)| 00:02:59 |
|   4 |     NESTED LOOPS OUTER             |                  | 1001 |   130K| 39354   (1)| 00:02:59 |
|   5 |      NESTED LOOPS SEMI             |                  |   970 |   111K| 36747   (1)| 00:02:47 |
|   6 |       NESTED LOOPS                 |                  |   970 |   104K| 34803   (1)| 00:02:39 |
|   7 |        NESTED LOOPS                |                  |   970 | 54320 | 32857   (1)| 00:02:30 |
|* 8 |         TABLE ACCESS BY INDEX ROWID| XYZ_INFO         |    19M|   704M| 28886   (1)| 00:02:12 |
|   9 |          INDEX FULL SCAN DESCENDING| DNIN_IDX_NI5     | 36967 |       |   296   (2)| 00:00:02 |
|* 10 |         TABLE ACCESS BY INDEX ROWID| XYZ_SUMMARY      |     1 |    19 |     2   (0)| 00:00:01 |
|* 11 |          INDEX UNIQUE SCAN         | SB11_DSMM_XYZ_UK |     1 |       |     1   (0)| 00:00:01 |
|* 12 |        TABLE ACCESS BY INDEX ROWID | XYZ              |     1 |    54 |     2   (0)| 00:00:01 |
|* 13 |         INDEX UNIQUE SCAN          | XYZ_PK           |     1 |       |     1   (0)| 00:00:01 |
|* 14 |       INDEX RANGE SCAN             | DNTI_NI1         |    32M|   249M|     2   (0)| 00:00:01 |
| 15 |      TABLE ACCESS BY INDEX ROWID   | XYZ_PNR_ERS      |     1 |    15 |     4   (0)| 00:00:01 |
|* 16 |       INDEX RANGE SCAN             | DNPE_XYZ         |     1 |       |     2   (0)| 00:00:01 |
Predicate Information (identified by operation id):
1 - filter("DISTRIB_CODE"='NS' AND "TIME_OPERATION">TO_DATE(' 2013-05-20', 'syyyy-mm-dd'))
2 - filter(ROWNUM<1002)
8 - filter("DI"."OPERATION"='CREATE')
10 - filter("DSUM"."DELIVERY_MODE"<>'DD' AND "DSUM"."PAYMENT_METHOD"<>'AC' AND "DSUM"."PAYMENT_METHOD"<>'AG')
11 - access("DSUM"."XYZ_ID"="DI"."XYZ_ID")
12 - filter("D"."PAYED"='N' AND "D"."XYZ_BLOCKED" IS NULL AND "D"."CANCEL_STATE"='N')
              ^^^^^^^^^^^^^^
13 - access("DI"."XYZ_ID"="D"."XYZ_ID")
14 - access("DT"."XYZ_ID"="D"."XYZ_ID")
16 - access("DPE"."XYZ_ID"(+)="D"."XYZ_ID")
plan with "d.payed = 'N'" (+/- 450 rows, less than two minutes):
| Id | Operation                          | Name             | Rows | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT                   |                  | 1001 | 4166K| 58604   (1)| 00:04:27 |
|* 1 | VIEW                              |                  | 1001 | 4166K| 58604   (1)| 00:04:27 |
|* 2 |   COUNT STOPKEY                    |                  |       |       |            |          |
|   3 |    VIEW                            |                  | 1002 | 4170K| 58604   (1)| 00:04:27 |
|   4 |     NESTED LOOPS OUTER             |                  | 1002 |   130K| 58604   (1)| 00:04:27 |
|   5 |      NESTED LOOPS SEMI             |                  | 1002 |   115K| 55911   (1)| 00:04:14 |
|   6 |       NESTED LOOPS                 |                  | 1476 |   158K| 52952   (1)| 00:04:01 |
|   7 |        NESTED LOOPS                |                  | 1476 | 82656 | 49992   (1)| 00:03:48 |
|* 8 |         TABLE ACCESS BY INDEX ROWID| XYZ_INFO         |    19M|   704M| 43948   (1)| 00:03:20 |
|   9 |          INDEX FULL SCAN DESCENDING| DNIN_IDX_NI5     | 56244 |       |   449   (1)| 00:00:03 |
|* 10 |         TABLE ACCESS BY INDEX ROWID| XYZ_SUMMARY      |     1 |    19 |     2   (0)| 00:00:01 |
|* 11 |          INDEX UNIQUE SCAN         | AAAA_DSMM_XYZ_UK |     1 |       |     1   (0)| 00:00:01 |
|* 12 |        TABLE ACCESS BY INDEX ROWID | XYZ              |     1 |    54 |     2   (0)| 00:00:01 |
|* 13 |         INDEX UNIQUE SCAN          | XYZ_PK           |     1 |       |     1   (0)| 00:00:01 |
|* 14 |       INDEX RANGE SCAN             | DNTI_NI1         |    22M|   168M|     2   (0)| 00:00:01 |
| 15 |      TABLE ACCESS BY INDEX ROWID   | XYZ_PNR_ERS      |     1 |    15 |     4   (0)| 00:00:01 |
|* 16 |       INDEX RANGE SCAN             | DNPE_XYZ         |     1 |       |     2   (0)| 00:00:01 |
Predicate Information (identified by operation id):
   1 - filter("DISTRIB_CODE"='NS' AND "TIME_OPERATION">TO_DATE(' 2013-05-20', 'syyyy-mm-dd'))
   2 - filter(ROWNUM<1002)
   8 - filter("DI"."OPERATION"='CREATE')
10 - filter("DSUM"."DELIVERY_MODE"<>'DD' AND "DSUM"."PAYMENT_METHOD"<>'AC' AND "DSUM"."PAYMENT_METHOD"<>'AG')
11 - access("DSUM"."XYZ_ID"="DI"."XYZ_ID")
12 - filter("D"."XYZ_BLOCKED" IS NULL AND "D"."CANCEL_STATE"='N')
13 - access("DI"."XYZ_ID"="D"."XYZ_ID")
14 - access("DT"."XYZ_ID"="D"."XYZ_ID")
16 - access("DPE"."XYZ_ID"(+)="D"."XYZ_ID")
XYZ.PAYED values breakdown:
P   COUNT(1)
Y   12202716
N    9430207
tables nb of records:
TABLE_NAME           NUM_ROWS
XYZ                  21606776
XYZ_INFO            186301951
XYZ_PNR_ERS           9716471
XYZ_SUMMARY          21616607
Everything that comes inside the "select * from(...) view" parentheses is defined in a view. We've noticed that the line "AND d.payed = 'N'" (commented above) is the guilty clause: the query takes one or two seconds to return between 400 and 500 rows if this line is removed, when included in the query, the response time then switches to *hours* -sic !- but then the result set is empty (no rows returned). The plan is exactly the same whether this "d.payed = 'N'" is added or removed, I mean the nb of steps, access paths, join order etc., only the rows/bytes/cost columns values change, as you can see.
We've found no other way of solving this perf issue but by taking out this "d.payed = 'N'" condition and setting it outside the view along with view.DISTRIB_CODE and view.TIME_OPERATION.
But we would like to understand why such a small change on the XYZ.PAYED column turns everything upside down that much, and we'd like to be able to tell the optimizer to perform this check on payed = 'N' by itself in the end, just like we did, through the use of a hint if possible...
Anybody ever encountered such a behaviour before ? Do you have any advice regarding the use of a hint to reach the same response time as that we've got by setting the payed = N condition outside of the view definition ??
Thanks a lot in advance.
Regards,
Seb

I am really sorry I couldn't get back earlier to this forum...
Thanks to you all for your answers.
First I'd just like to correct a small mistake I made, when writing
"the query takes one or two seconds": I meant one or 2 *minutes*. Sorry.
> What table/columns are indexed by "DNTI_NI1"?
aaaa.dnti_ni1 is an index ON aaaa.xyz_ticket(xyz_id, ticket_status)
> And what are the indexes on xyz table?
Too many:
XYZ_ARCHIV_STATE_IND           ARCHIVE_STATE
XYZ_BENE_CUST_ID_IND           BENE_CUST_ID
XYZ_BENE_TTL_IND               BENE_TTL
XYZ_CANCEL_STATE_IND           CANCEL_STATE
XYZ_CLIENT_APP_NI              CLIENT_APP
XYZ_CRM_CUST_ID_IND            CRM_CUST_ID
XYZ_DELIVE_MODE_IND            DELIVERY_MODE
XYZ_DELIV_BLOCK_IND            DELIVERY_BLOCKED
XYZ_DELIV_STATE_IND            DELIVERY_STATE
XYZ_XYZ_BLOCKED                XYZ_BLOCKED
XYZ_FIRST_TRAVELDATE_IND       FIRST_TRAVELDATE
XYZ_MASTER_XYZ_IND             MASTER_XYZ_ID
XYZ_ORG_ID_NI                  ORG_ID
XYZ_PAYMT_STATE_IND            PAYMENT_STATE
XYZ_PK                         XYZ_ID
XYZ_TO_PO_IDX                  TO_PO
XYZ_UK                         XYZ_NUM
For ex. XYZ_CANCEL_STATE_IND on CANCEL_STATE seems superfluous to me, as the column may only contain Y or N (or be null)...
> Have you traced both cases to compare statistics? What differences did it reveal?
Yes but it only shows more of *everything* (more tables blocks accessed, the same
for indexes blocks, for almost all objects involved) for the slowest query !
Greping WAIT on the two trc files made for every statement and counting the
object IDs access show that the quicker query requires much less I/Os; the
slowest one overall needs much more blocks to be read (except for the indexes
DNSG_NI1 or DNPE_XYZ for example). Below I replaced obj# with the table/index
name, the first column is the figure showing how many times the object was
accessed in the 10053 file (I ctrl-C'ed my second execution ofr course, the
figures should be much higher !!):
[login.hostname] ? grep WAIT OM-quick.trc|...|sort|uniq -c
    335 XYZ_SUMMARY
20816 AAAA_DSMM_XYZ_UK (index on xyz_summary.xyz_id)
    192 XYZ
   4804 XYZ_INFO
    246 XYZ_SEGMENT
      6 XYZ_REMARKS
     63 XYZ_PNR_ERS
    719 XYZ_PK           (index on xyz.xyz_id)
   2182 DNIN_IDX_NI5     (index on xyz.xyz_id)
    877 DNSG_NI1         (index on xyz_segment.xyz_id, segment_status)
    980 DNTI_NI1         (index on xyz_ticket.xyz_id, ticket_status)
    850 DNPE_XYZ         (index on xyz_pnr_ers.xyz_id)
[login.hostname] ? grep WAIT OM-slow.trc|...|sort|uniq -c
   1733 XYZ_SUMMARY
38225 AAAA_DSMM_XYZ_UK (index on xyz_summary.xyz_id)
   4359 XYZ
12536 XYZ_INFO
     65 XYZ_SEGMENT
     17 XYZ_REMARKS
     20 XYZ_PNR_ERS
   8598 XYZ_PK
   7406 DNIN_IDX_NI5
     29 DNSG_NI1
   2475 DNTI_NI1
     27 DNPE_XYZ
The overwhelmingly dominant wait event is by far 'db file sequential read':
[login.hostname] ? grep WAIT OM-*elect.txt|cut -d"'" -f2|sort |uniq -c
     36 SQL*Net message from client
     38 SQL*Net message to client
107647 db file sequential read
      1 latch free
      1 latch: object queue header operation
      3 latch: session allocation
> It will be worth knowing the estimations...
It show the same plan with a higher cost when PAYED = N is added:
SQL> select * from sb11.dnr d
2* where d.dnr_blocked IS NULL and d.cancel_state = 'N'
SQL> /
| Id | Operation                   | Name                 | Rows | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT            |                      | 1002 |   166K|    40   (3)| 00:00:01 |
|* 1 | TABLE ACCESS BY INDEX ROWID| XYZ                  | 1002 |   166K|    40   (3)| 00:00:01 |
|* 2 |   INDEX RANGE SCAN          | XYZ_CANCEL_STATE_IND |       |       |     8   (0)| 00:00:01 |
Predicate Information (identified by operation id):
   1 - filter("D"."XYZ_BLOCKED" IS NULL)
   2 - access("D"."CANCEL_STATE"='N')
SQL> select * from sb11.dnr d
2 where d.dnr_blocked IS NULL and d.cancel_state = 'N'
3* and d.payed = 'N'
SQL> /
Execution Plan
Plan hash value: 1292668880
| Id | Operation                   | Name                 | Rows | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT            |                      | 1001 |   166K|    89   (3)| 00:00:01 |
|* 1 | TABLE ACCESS BY INDEX ROWID| XYZ                  | 1001 |   166K|    89   (3)| 00:00:01 |
|* 2 |   INDEX RANGE SCAN          | XYZ_CANCEL_STATE_IND |       |       |    15   (0)| 00:00:01 |

Itunes slows down when sharing music is enabled

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by the way: i'd loooooove to see pandora-like functionality in the next major versin of itunes!!! :)))

When you are sharing your iTunes, any other users you share with are accessing your hard drive and music foilder simultaneously with you. Since shared users are not playing exactly the same song at the same time as you, your hard drive's heads are scanning and reading from more points than they would be with you alone listening. There is a need to cache some part of the files for sharing, and that uses a bit of your RAM too. I guess it would be similar to saying that your car drives fine as long as you are driving it alone. Pile a few friends in with you, tow their cars behind yours, and suddenly, your car has nowhere near the performance it did with just you in it. Aside from adding more RAM, buying a fatser hard drive or stepping up your processor, this is simply an issue with sharing one system between more than one user at the same time, and it can't be remedied.

Query slows down after upgrade

Hi,
After upgrade from oracle 10 to oracle 11 a simple query is slowing down alot.
Same amount of records, same table only the execution cost time is increased
Can someone give me some feedback over this problem?
Can I check some things to look into the problem?
Thx in advance.
Greetings
query:
Select nvl(sum(a.BM_OPENSTAAND_DEBET- a.BM_OPENSTAAND_CREDIT),0)
from bh.bh123gh a
where
a.F123_AR_NR>='4400000000' and
a.F123_AR_NR<='4404000000' and
a.F123_KL_LEV_AR_NR='0631001000' and
a.SRT_REK=2 and
a.F123_BKJR>=0000 and
a.F123_BKJR<=2011 and
a.F123_FIRMA=2
explain plans
oracle 11
cost 1,792
Bytes: 38
Cardinality: 1
oracle 10
cost 1,594
Bytes: 38
Cardinality: 1

>
After upgrade from oracle 10 to oracle 11 a simple query is slowing down alot.
Same amount of records, same table only the execution cost time is increased
Can someone give me some feedback over this problem?
Can I check some things to look into the problem?
Thx in advance.
>
Is it just one query or all queries are behaving strangely? If it's just one query, do a trace and see where it's slowing down.
In the meanwhile, you can also modify the optimizer_features_enable parameter at session level and check the explain plan.
Alter session set optimizer_features_enable='10.2.0.5';
Now test the query.
By the way, if you are just worried about the COST factor, you can just ignore it. COST by itself has no real meaning. You will only have to look at the response time.
Regards

Query slow down when added a where clause

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