Performance Tuning :: Oracle 11g Alternates Between Two Execution Plans?

Apr 3, 2012

We have a query which makes Oracle behave very strangely. It is a straight-forward join between four tables of about 30.000 rows each, with some simple comparisons and some NOT LIKE:s.

When we run this query, it either takes about 1 second or more than 1.000 seconds to run and return the approximately 5.000 rows of the result. If we run the same query over and over again, it fluctuates back and forth between two different execution plans, apparently at random, 3 times out of 4 selecting the 1.000 second version and 1 time out of 4 the 1 second version.

There are no other connections to the database, the schema is not modified, the data is identical, the query is identical, and the response is identical, but the execution time alternates between 1 second and 1.000 seconds.On the same database instance we have another schema which is identical, but with slightly less data, which is used for development. The 1.000 second run times did not happen in that schema, but only in the test system's database.

Therefore we would REALLY like to understand what happens and why, so that we can avoid triggering this in the future. We could try locking the 1 second execution plan, but then we're afraid of doing the same thing wrong again in the future.

Here are the two execution plans that Oracle switches between, more or less at random:

Rows (1st) Rows (avg) Rows (max) Row Source Operation
---------- ---------- ---------- ---------------------------------------------------
5455 5455 5455 HASH JOIN (cr=15663 pr=10536 pw=0 time=855673 us cost=82273 size=2707430769293 card=14028138701)
79272 79272 79272 TABLE ACCESS FULL GROUPS (cr=1008 pr=0 pw=0 time=22154 us cost=277 size=10693 card=289)

[code]...

Rows (1st) Rows (avg) Rows (max) Row Source Operation
---------- ---------- ---------- ---------------------------------------------------
5455 5455 5455 HASH JOIN (cr=15664 pr=0 pw=0 time=778178696 us cost=30838477 size=741611997206725 card=3842549208325)
375411 375411 375411 TABLE ACCESS FULL GROUP_GROUPS_FLAT (cr=3782 pr=0 pw=0 time=51533 us cost=1029 size=25152738 card=375414)

[code]...

The query:

select g.ucid, a.ucid
from account a, groups g, group_members gm, group_groups_flat ggf
where a.ucid = gm.ucid_member
and gm.ucid_group = ggf.ucid_member

[code]...

And excerpts from the schema:
CREATE TABLE "PDB"."GROUPS"
(
"UCID" VARCHAR2(256 BYTE),
"UNIX_GID" NUMBER(*,0),
[...]

[code]...

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Performance Tuning :: Same Query Using Different Execution Plans?

Dec 26, 2011

I am executing the query below:

INSERT INTO temp_vendor(vendor_record_seq_no,checksum,rownumber,transaction_type,iu_flag)
SELECT /*+ USE_NL ( vd1 ,vd2 ,vd3 ) leading ( vd1 ,vd2 ,vd3 , tvd) */ vd1.vendor_record_seq_no, tvr.checksum, tvr.rownumber, tvr.transaction_type, 'U'
FROM vendor_data vd1,
vendor_data vd2,
vendor_data vd3,
(SELECT rownumber,

[code]....

It is taking different approaches (execution plans) while executing for same set of parameters. Due to which sometimes it executes successfully, but sometimes it fills all TEMP space and get failed. I am pasting both the execution plan (different from expalin plan) below:

I. Successfull Execution Plan:

------------------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | Pstart| Pstop |
------------------------------------------------------------------------------------------------------------------------
| 0 | INSERT STATEMENT | | | | 65612 (100)| | | |
|* 1 | HASH JOIN | | 1 | 6121 | 65612 (1)| 00:13:08 | | |

[code]....

II. Failed with TEMP space Execution Plan:

--------------------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | Pstart| Pstop |
--------------------------------------------------------------------------------------------------------------------------
| 0 | INSERT STATEMENT | | | | 1967 (100)| | | |
|* 1 | FILTER | | | | | | | |
| 2 | SORT GROUP BY | | 1 | 8233 | 1967 (3)| 00:00:24 | | |
|* 3 | HASH JOIN | | 1 | 8233 | 1966 (3)| 00:00:24 | | |

[code]....

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Performance Tuning :: Possible To Display Alternate Execution Plans

Jan 27, 2012

When we use the AUTOTRACE / EXPLAIN PLAN we can see the (estimated) best execution plan the Optimizer found for our SQL Command. Is there a way to display all alternate execution plans the Optimizer has considered ?

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Performance Tuning :: Adding +0 And -0 To A Number Predicate Produces Different Plans

Apr 29, 2011

I have a weird optimizer behaviour on a 10.2.0.4 db.When i add "+0" or "-0" to a number predicate, the optimizer produces 2 differents plans. I dont see why. Here are the statements:

A -First statement with suboptimal plan :

SELECT /*KO*/ TFXPPRODUCT.PRODUCTID,
TFXPPRODUCT.PRODUCTTYPE,
VFUTFIX.Datech,
TFXPPRODUCT.SHORTLABEL,
VFUTFIX.TAUCPN,
VFUTFIX.Tik,
[code]....

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Performance Tuning :: Query Taking High CPU And Execution Time In Oracle 11gR2

Dec 24, 2012

The below query is taking high CPU almost 98% and longer time to execute.

SELECT ancestor,
Max(D.alarmstate) ALARMSTATE,
Max(D.sialarmstate) SIALARMSTATE,
Max(D.uncralarmstate) UNCRALARMSTATE,
Max(M.commstate) COMMSTATE,
Max(M.nncommstate) NNCOMMSTATE,
Max(M.servicestate) SERVICESTATE,
Max(M.abnormal) ABNORMAL,
CASE
[code]....

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Different Execution Plans For Same SQL In 10R2

Jan 14, 2013

DB=10.2.0.5
OS=RHEL 3

Im not sure of this, but seeing different plans for same SQL.

select sql_text from v$sqlarea where sql_id='92mb4z83fg4st'; <---TOP SQL from AWR

SELECT /*+ OPAQUE_TRANSFORM */ "ENDUSERID","LASTLOGINATTEMPTTIMESTAMP","LOGINSOURCECD","LOGINSUCCESSFLG",
"ENDUSERLOGINATTEMPTHISTORYID","VERSION_NUM","CREATEDATE"
FROM "BOMB"."ENDUSERLOGINATTEMPTHISTORY" "ENDUSERLOGINATTEMPTHISTORY";
[code]....

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Multiple Execution Plans For Sql_id From AWR

Aug 23, 2012

multiple execution plns for the sql_id from AWR,i have following questions

1.which plan is opimizer tcurrently using ?
2.how to make sure optimizer to pick right plans

SQL> select * from table(dbms_xplan.display_awr('fb0p0xv370vmb')) ;
PLAN_TABLE_OUTPUT
SQL_ID fb0p0xv370vmb
[code]....

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Performance Tuning :: Different Execution Plan In Different DB

Jul 20, 2013

Why the query is behaving differently with the different database.(execution plan)

Whatever the production database is having same database instance replicated to a new schema. I tried both the queries running on both environment.In prod the index has been used but in newdev it is not. This case existing primary key index were not been used.

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Performance Tuning :: Avg Time Taken By Execution Plan

Apr 12, 2013

How can i check the avg time taken by an execution plan. Actually i have a very big query and it changes its execution plan very often, we would like to lock the best execution plan and to find it , i would like to know the Average Execution Time the query takes when it runs using different different execution plans.

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Performance Tuning :: How To Change Execution Order

May 2, 2012

Performance issues with the below mentioned sql.After gone through execution plan we have found out the reason but we couldn't able to change the execution plan the way we want.

If we could able to join

HRMGR.HR_EXPANDED_BOOK table with MISBOMGR.ibm_client_mgr7_empid, MISBOMGR.ibm_client_mgr6_empid at earlier stage means before HRMGR.HR_EMP_STATUS_LOOKUP then my issue will be solved but somehow optimizer is not considering that path. Even i have added push_subq hint which will push sub queries to execute at earlier stage but no use. Why push_subq hint is not working in this scenario and what can be the other alternative to change the driving path.

Query :-

select /*+ push_subq */CEMP.EMP_ID,
CEMP.EMP_STATUS_CD,
EMP_STATUS_DESC,
MGR_6_EMP_ID,
MGR_7_EMP_ID
FROM
[code]........

Execution plan :-
------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | Inst |IN-OUT|
------------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 16958 | 927K| 12008 (2)| 00:02:25 | | |
|* 1 | FILTER | | | | | | | |
| 2 | MERGE JOIN OUTER | | 173K| 9511K| 12008 (2)| 00:02:25 | | |
| 3 | REMOTE | HR_EXPANDED_BOOK | 173K| 7303K| 12005 (2)| 00:02:25 | INFODB | R->S |
|* 4 | SORT JOIN | | 11 | 143 | 3 (34)| 00:00:01 | | |
| 5 | REMOTE | HR_EMP_STATUS_LOOKUP | 11 | 143 | 2 (0)| 00:00:01 | INFODB | R->S |
|* 6 | TABLE ACCESS FULL| IBM_CLIENT_MGR7_EMPID | 1 | 8 | 2 (0)| 00:00:01 | | |
|* 7 | TABLE ACCESS FULL| IBM_CLIENT_MGR6_EMPID | 1 | 8 | 3 (0)| 00:00:01 | | |
------------------------------------------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
1 - filter( EXISTS (SELECT /*+ USE_HASH ("IBM_CLIENT_MGR7_EMPID") */ 0 FROM
"MISBOMGR"."IBM_CLIENT_MGR7_EMPID" "IBM_CLIENT_MGR7_EMPID" WHERE "MGR_7_EMP_ID"=:B1) OR EXISTS
(SELECT 0 FROM "MISBOMGR"."IBM_CLIENT_MGR6_EMPID" "IBM_CLIENT_MGR6_EMPID" WHERE "MGR_6_EMP_ID"=:B2))
4 - access("CEMP"."EMP_STATUS_CD"="EMPLU"."EMP_STATUS_CD"(+))
filter("CEMP"."EMP_STATUS_CD"="EMPLU"."EMP_STATUS_CD"(+))
6 - filter("MGR_7_EMP_ID"=:B1)
7 - filter("MGR_6_EMP_ID"=:B1)

Remote SQL Information (identified by operation id):
----------------------------------------------------
3 - SELECT "EMP_ID","EMP_STATUS_CD","MGR_6_EMP_ID","MGR_7_EMP_ID" FROM
"HRMGR"."HR_EXPANDED_BOOK" "SYS_ALIAS_2" WHERE "EMP_STATUS_CD"='P' (accessing 'INFODB' )
5 - SELECT "EMP_STATUS_CD","EMP_STATUS_DESC" FROM "HRMGR"."HR_EMP_STATUS_LOOKUP" "EMPLU"
(accessing 'INFODB' )

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Performance Tuning :: Execution Plan Of SQL Statement

Mar 25, 2012

I have queries on the execution plan of a sql statement

Following is the example

create table t1 as select s1.nextval id,a.* from dba_objects a;
create table t2 as select s2.nextval id,a.* from dba_objects a;
insert into t1 select s1.nextval id,a.* from dba_objects a;
insert into t1 select s1.nextval id,a.* from dba_objects a;
insert into t2 select s2.nextval id,a.* from dba_objects a;
insert into t2 select s2.nextval id,a.* from dba_objects a;
insert into t2 select s2.nextval id,a.* from dba_objects a;
commit;

create index i1 on t1(id);
create index i2 on t2(id);
create index i11 on t1(object_type);

exec dbms_stats.gather_table_stats(user,'T1',cascade=>true);
exec dbms_stats.gather_table_stats(user,'T2',cascade=>true);

select count(*) from t1 where object_type='VIEW';

COUNT(*)
----------
8934

set autotrace traceonly explain

Can we say in the following case, that,

(1) First index on object_type is accessed to get rowids - t1.object_type='VIEW'
(2) Then the filter on owner is applied - t1.owner='SYS'
(3) Then the table T1 is accessed to fetch data from the rowids returned by the index I11 and filer application - TABLE ACCESS BY INDEX ROWID

Though I am unable to understand how filter can be applied to the rowids retrieved from index, we can see from the plan below that The rows accessed have reduced from 8550 to 1221 before we access the table...Thus filter "t1.owner='SYS'" is applied in between. Right?

another question is

Case 1 - do we retrieve a rowid from index for a given value, then retrieve required values from table for that rowid
Thus row at a time in both ... in loop
OR
Case 2 - we first fetch all rowids from index and then retrieve values from table one row at a time from the collection of rowids fetched?

Suppose Case 1 is what is happening then can we say, both the steps mentioned by IDS 2,3 in plan below are executed exactly equal number of times and the filter "t1.owner='SYS'" is applied at some later stage? Of course in this case the values in ROWS stand misleading then

select * from t1,t2 where t1.id = t2.id and t1.object_type='VIEW' and t1.owner='SYS';

Execution Plan
----------------------------------------------------------
Plan hash value: 26873579
-------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
-------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1221 | 233K| 915 (1)| 00:00:11 |
|* 1 | HASH JOIN | | 1221 | 233K| 915 (1)| 00:00:11 |
|* 2 | TABLE ACCESS BY INDEX ROWID| T1 | 1221 | 116K| 381 (1)| 00:00:05 |
|* 3 | INDEX RANGE SCAN | I11 | 8550 | | 24 (0)| 00:00:01 |
| 4 | TABLE ACCESS FULL | T2 | 161K| 15M| 533 (1)| 00:00:07 |
-------------------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
1 - access("T1"."ID"="T2"."ID")
2 - filter("T1"."OWNER"='SYS')
3 - access("T1"."OBJECT_TYPE"='VIEW')

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Performance Tuning :: SQL Execution Plan Different On Different Hardware

Oct 31, 2012

So the situation is like this

- Database A (20 tables)
- Database B (20 tables)

- Both A and B are Oracle 11gR2

- Both of these databases run on different hardware (A is a VM, B is on a physical host)

- The 20 tables in A and B have exactly same number of rows and after preparing the data, the schemas were analysed using the same DBMS_STATS parameters

Despite this, the execution plans appear to be quite different for the same queries between A and B

I imagine there is something outside of the Oracle table rowcounts, table stats, column stats, index stats that's resulting in the different execution plans.

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Performance Tuning :: Achieve Same Execution Plan?

Apr 30, 2012

refere to below 2 queries and their execution plans:

First Query
INSERT INTO temp_vendor(vendor_record_seq_no,checksum,rownumber,transaction_type,iu_flag)
SELECT /*+ USE_NL ( vd1 ,vd2 ,vd3 ) leading ( vd1 ,vd2 ,vd3 , tvd) */
vd1.vendor_record_seq_no, tvr.checksum, tvr.rownumber, tvr.transaction_type, 'U'
FROM vendor_data vd1,

[code]...

Second Query
SELECT vd1.vendor_record_seq_no, tvr.checksum, tvr.rownumber, tvr.transaction_type, 'U'
FROM ( select * from vendor_data vd1
where vd1.study_seq_no = 99903
AND vd1.control_column_seq_no = 435361232

[code]...

Both are to achieve same output but written in different ways. CAn I get same exectuion plan from 1st query as there is for 2nd using hints

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Performance Tuning :: Execution Plan Changing With Same SQL Profile

Mar 5, 2013

One of our clients is using Rule Based Optimizer on Oracle 10.2.0.3.0

2-3 weeks backs, during performance issue in one of the sql queries, one of our team members executed tuning adviser for it, created SQL profile and the subsequent execution of the SQL did not took much time (less I/O). Now it took hardly a minute to execute

When this happened I checked that the SQL profile forced that particular query to use CBO (say plan_hash_value is PHV1 here). Yesterday the same query again took 15-20 minutes for execution. I checked that even for this execution the query used the same SQL profile but "this time" with different plan_hash_value - say PHV2.

Today again the query executed in less than a minute and used the plan_hash_value as PHV1.

select distinct plan_hash_value,timestamp from dba_hist_sql_plan where sql_id='mysqlid' order by 1,2;

PLAN_HASH_VALUE TIMESTAMP
--------------- --------------------
890360113 20-feb-2013 16:38:39
3736413466 04-mar-2013 08:12:52
1237282258 03-jan-2013 17:15:02

I confirmed from awrsqrpt as well that different plans were used for different plan_hash_values and every time same SQL profile was used

SQL> select name,CATEGORY,SIGNATURE,CREATED,LAST_MODIFIED,TYPE,STATUS,FORCE_MATCHING from dba_sql_profiles;

NAME CATEGORY SIGNATURE CREATED LAST_MODIFIED TYPE STATUS FOR
------------------------------ ------------------------------ ---------- -------------------- -------------------- --------- -------- ---
SYS_SQLPROF_015ffffcc3e1c5b000 DEFAULT 1.5512E+19 20-feb-2013 16:30:48 20-feb-2013 16:30:48 MANUAL ENABLED NO

I am unable to understand how execution plan and thus plan_hash_value is changing for the same SQL Profile. I read that SQL Profile (unlike stored outline) keeps up with increasing data volume and may not keep up with changing data distribution.

I checked that values for 4 bind variables out of 81 are different for execution between today and yesterdays' run(queried v$sql_bind_capture based on last_captured)

My questions are
1) does the different plan_hash_values with different execution plans for query using same SQL profile mean the query was hard parsed multiple times and still used the same SQL profile?
2) If that is the case why I never saw child_number = 1 in any of the views for the same sql_id. I tried it repeatedly over last 2 weeks and always found child_number=0 in v$sql (also loaded_versions=1)
3) Does the different values of bind variable are causing this flip-flop of the plans? How can I conclude this?

I have 2 plans with 2 different plan_hash_values. I know which would be better. How can I force the sql to use better plan in the two in this case where I am using Rule Based Optimizer and have SQL profile created If this is not possible then how can I create stored outline from the existing plan (not waiting for subsequent execution to take place).

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Performance Tuning :: Lost Index From Second Execution Time?

Jul 11, 2013

The problem was describe:

- First time to execute: Using all indexes on 2 tables

- Second time to execute: Using only indexes on first table, full table scan on the other

- Third time to execute: Do FTS on both of tables.

Now, I show the objects and relate information here:

The Tables:

system@dbwap> select count(*) from my_wap.news_relation;

COUNT(*)
----------
272708

system@dbwap> select count(*) from my_wap.news_content;

COUNT(*)
----------
95092

system@dbwap> desc my_wap.news_content;
Name Null? Type
----------------------------------------------------- -------- ----------------
ID NOT NULL NUMBER(11)
SUBJECT NOT NULL VARCHAR2(500)
TITLE VARCHAR2(4000)
STATE NUMBER(1)
IMGPATH VARCHAR2(500)
ALIGN VARCHAR2(10)

[Code]....

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Enterprise Manager :: Top Activity - How To Increase Number Of Execution Plans Kept

Feb 1, 2010

When viewing SQL statements in Top Activity in OEM, I am only able to see the Explain Plan for the most recent statement. Is there a setting to increase the number execution plans kept?

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Performance Tuning :: Delete Statement Is Taking More Time For Execution?

Mar 9, 2010

In my code I am using delete statement which is taking too much time to execute.

Statement is as follow:

DELETE FROM TRADE_ORDER_EMP_ALLOCATION T
WHERE (ARTEMIS_SOURCE_SYSTEM_ID,NM_ARTEMIS_SOURCE_SYSTEM,CD_BOOK_KEY,ACTIVITY_DT)
IN (SELECT ARTEMIS_SOURCE_SYSTEM_ID,NM_ARTEMIS_SOURCE_SYSTEM,CD_BOOK_KEY,ACTIVITY_DT
FROM LOAD_TRADE_ORDER
WHERE IND_IS_BAD_RECORD='N');

Tables Used:
oTRADE_ORDER_EMP_ALLOCATION Row count (329525880)
oLOAD_TRADE_ORDER Row count (29281)

Every column in "IN" clause and select clause is containing index on it

Every time no of rows which to be deleted is vary (May be in hundred ,thousand or hundred thousand )so that I am Unable to use "BITMAP" index on the table "LOAD_TRADE_ORDER" column "IND_IS_BAD_RECORD" though it is containing distinct record in it.

Even table "TRADE_ORDER_EMP_ALLOCATION" is containing "RANGE" PARTITION over it on the column "ARTEMIS_SOURCE_SYSTEM_ID". With this I am enclosing table scripts with Indexes and Partitions over it.

way for fast execution in of above delete statement?

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Performance Tuning :: How To Change Execution Plan Of Currently Executing Statement

Feb 8, 2011

refer following sql statements and code

Session 1
create table tab1 as select * from dba_objects where object_id is not null;
alter session set events '10046 trace name context forever, level 12';
declare
x number;
begin
for i in 1..4
loop

[code]....

Session 2

after "starting" the above pl/sql block from Session 1, I keep on querying tab2 from Session 2 And as soon as 2 records are inserted in tab2, I create index from Session 2

select * from tab2;
select * from tab2;
select * from tab2;
N
----------
1
2
create index i on tab1(object_id);

As I have tested from a single session (just before this test) such index is used for the sql statement

select count(1) into x from tab1 where object_id=2331;

However when I checked the trace file I am not geeting results as expected

I am expecting 4 execution plans - 2 FTS and 2 Index Access scans and for this I am issuing following command

tkprof dst1_ora_7369.trc dst1_ora_7369.txt aggregate=no sys=no

But unfortunately I am getting following output

SELECT COUNT(1)
FROM
TAB1 WHERE OBJECT_ID=2331
call count cpu elapsed disk query current rows
------- ------ -------- ---------- ---------- ---------- ---------- ----------
Parse 1 0.00 0.00 0 1 0 0
Execute 4 0.00 0.00 0 2 0 0

[code]....

1) Why I am unable to see 4 execution plans - 2 with FTS and 2 with Index access when I mentioned 'aggregate=no'?

2) Whether the index i will be used for last 2 iterations after first 2 iterations of FTS?

If answer to above question 2) is 'No'

By which method I can force an ongoing sql statement in loop to take different execution path? Of course I can't hard parse sql in 'that' current session Will flushing Shared pool work in above case?

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Performance Tuning :: Explain Plan Analysis - Execution Ordering

Jul 21, 2010

I have two Oracle instances that are setup identically.When I run a query on one of them, it takes around 3 seconds, on the other it takes around 200 seconds.

I have looked at the explain plans, and it has shown me what I think is the problem. On one instance, it does a join on two tables, then runs the other filter/access predicates. On the other instance it runs the filter/access predicated first, then does the expensice join. The one that does the join first is the one that takes around 200 seconds. How to tell Oracle to make this join after runnning the other predicates?

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Performance Tuning :: Same Execution Plan For Create Table Statement When Name Changes?

May 18, 2010

Can we have same execution plan for a create table statement where the name of the table changes every time as follows:

create table test
as
select * from t1

Here table name changes from test to another table name next time

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Performance Tuning :: Increased LOGFILE Capacity Not Decrease Execution Time?

Aug 6, 2012

I'm planning to decrease the time taken to execute data by managing the redo log file but I'm kinda stuck in some aspect : > Why is my OPTIMAL_LOGFILE_SIZE is showing NULL ? > I'm trying to resize the LOGFILE capacity from 100M to 200M and I'm also adding 1 more LOG GROUP with 200M capacity too but turned out that didn't decrease my execution time.

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Performance Tuning :: Why Elapsed Time Changed While Execution Plan And Stats Remains The Same

Jun 4, 2010

attached query giving consistent execution plan but different timings across run

SELECT /*+ INDEX (CRT CRT_CUN_FK_I)*/
DISTINCT odr.dve_id
FROM company_requirements crt, orders odr, lelo_products la_pct
WHERE crt.qtn_cun_id = 10035637--10000021--10035667
AND crt.ID = odr.crt_id_quote_implemented
AND NVL (odr.cancellation_date, '31-Dec-9999') = '31-Dec-9999'

[code]....

we have 4 databases, 2 on each servers, such that db1 and db2 on server1 and db3 and db4 on server2

refer count of the records for column of biggest table in the query, taken on all 4 databases (The column is nullable)

select count(*) from company_requirements crt WHERE crt.qtn_cun_id = 10035637
db1 = 73335
db2 = 89073
db3 = 81182
db4 = 82936

First I executed the query on db1 and db2 while there wasn't any user logged on to the system

db1
**********
call count cpu elapsed disk query current rows
------- ------ -------- ---------- ---------- ---------- ---------- ----------
Parse 1 0.06 0.08 0 0 0 0
Execute 1 0.00 0.00 0 0 0 0
Fetch 1 17.47 473.39 85704 1508102 0 0

[code]...

Elapsed times include waiting on following events:

Event waited on Times Max. Wait Total Waited
---------------------------------------- Waited ---------- ------------
SQL*Net message to client 1 0.00 0.00
db file sequential read 85704 0.31 460.55
latch free 1 0.00 0.00
SQL*Net message from client 1 14.98 14.98

[code]...

Why the elasped time changed when data and plan hasn't changed at all? Also why the plan has different stats for round 1 and 2 on db1 and db2?

I ran it 2 times each round each database so hard parsing shall not be issue.Also why the number of rows accessed are different in db1,db2 and db3,db4 especially for step1 when count of crt.qtn_cun_id is similar?

In fact when the query was taking long I was the only user on the system Also I used hard coded value (no bind variables at all)

I checked num_rows, distinct keys as well which are quite similar across all 4 databases Also no stats where gather during the query execution

What I should have checked or monitored?

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Performance Tuning :: Order Of Steps In Execution Path And Order Of Predicates In The Plan

Mar 20, 2012

Which step in the following plan is the first step of execution

I reckon it is "TABLE ACCESS BY INDEX ROWID| BANK_BATCH_STATE"

Is that correct?

In the "Predicate Information (identified by operation id):"

section the predicates - access and filter for the step "TABLE ACCESS FULL | PYMNT_DUES" are displayed first

Isn't there any relation between the order of execution steps and the order in which predicates are displayed?

Execution Plan
----------------------------------------------------------
Plan hash value: 538700484
-------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
-------------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 2364 | 15 (14)| 00:00:01 |
|* 1 | FILTER | | | | | |
| 2 | HASH GROUP BY | | 1 | 2364 | 15 (14)| 00:00:01 |
| 3 | NESTED LOOPS | | 1 | 2364 | 14 (8)| 00:00:01 |
| 4 | NESTED LOOPS | | 1 | 2313 | 13 (8)| 00:00:01 |
| 5 | NESTED LOOPS | | 1 | 2281 | 12 (9)| 00:00:01 |
| 6 | NESTED LOOPS OUTER | | 1 | 2255 | 11 (10)| 00:00:01 |
|* 7 | HASH JOIN | | 1 | 175 | 6 (17)| 00:00:01 |
|* 8 | INDEX RANGE SCAN | INDX_2 | 12 | 612 | 2 (0)| 00:00:01 |
|* 9 | TABLE ACCESS FULL | PYMNT_DUES | 43 | 5332 | 3 (0)| 00:00:01 |
| 10 | VIEW PUSHED PREDICATE | | 1 | 2080 | 5 (0)| 00:00:01 |
| 11 | NESTED LOOPS | | 1 | 154 | 5 (0)| 00:00:01 |
| 12 | NESTED LOOPS | | 1 | 103 | 4 (0)| 00:00:01 |
|* 13 | TABLE ACCESS BY INDEX ROWID| BANK_BATCH_STATE | 1 | 32 | 2 (0)| 00:00:01 |
|* 14 | INDEX RANGE SCAN | INDX_BBS_1 | 3 | | 1 (0)| 00:00:01 |
|* 15 | TABLE ACCESS BY INDEX ROWID| DAILY_CHECK | 1 | 71 | 2 (0)| 00:00:01 |
|* 16 | INDEX RANGE SCAN | INDX_SEARCH | 1 | | 1 (0)| 00:00:01 |
|* 17 | INDEX RANGE SCAN | INDX_2 | 1 | 51 | 1 (0)| 00:00:01 |
|* 18 | INDEX RANGE SCAN | INDX_IAM_SR_NO | 1 | 26 | 1 (0)| 00:00:01 |
|* 19 | INDEX RANGE SCAN | INDX_2 | 1 | 32 | 1 (0)| 00:00:01 |
|* 20 | INDEX RANGE SCAN | INDX_2 | 1 | 51 | 1 (0)| 00:00:01 |
-----------------------------------------------------------------

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Jul 12, 2013

I have installed database in one server. I would like to enable AWR into it. Statistics_level is set to Typical. While running the below script to enable the AWR, its gives error -

SQL> exec dbms_scheduler.enable('GATHER_STATS_JOBS');
BEGIN dbms_scheduler.enable('GATHER_STATS_JOBS'); END;

*
ERROR at line 1:
ORA-27476: "SYS.GATHER_STATS_JOBS" does not exist
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make AWR automatical generation.

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I am running an Oracle 10.2.0.3 on Solaris 5.9 OS. Front end appplication is PeopleSoft v8.8.From my AWR report I have found below SQL which needs to be tuned:

SELECT TO_CHAR (TO_DATE (TO_CHAR (B.ASOFDATE, 'YYYY-MM-DD'), 'yyyy-mm-dd'),
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[code]...

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Our Web app (developed with .NET) reads those images just to display them on a Web Session (IE).As you can see, what we are doing now works fine. But network sometimes is an issue and also it's hard to keep synchronization with our DR server, backups, etc.

Are we taking the correct approach? It would be better to have the images in CLOB or BLOBS for better performance? If so, As I mentioned, performance is the KEY FACTOR and the most important item to consider in this design.

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my query is
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SQL> set autotrace traceonly stat
SQL> set timi on

[Code]....

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