Tuning of Individual SQL statement

Hi all,
One of my developer come to me stating that the query is taking long time. In this case, how i have to
deal/tell with this from interview point of view.
1. I will say, first, i will see whether Indexes are there or not.
2. Join conditions.
Then what are the steps, i have to follow to see what is the bottleneck and how to rectify it.
Thanks in advance,
Pal

HI,
Please first read the links Alex provided earlier today, they explain clearly what to do:
Query works great in 9i, but on 10g massive slow down.

Similar Messages

Tuning a stubborn SQL statement

Hello,
I have performance problems with this SQL statement:
SELECT
T_00 . "FBRNR" , T_00 . "FBFNR" , T_01 . "DIVISION" , T_01 . "SERVCODE" , T_01 . "KUNSND" ,
T_01 . "KUNRCV" , T_01 . "KUNREG" , T_01 . "LFBED" , T_00 . "ABRDAT" , T_01 . "REGNL"
FROM
"ZFBINFO" T_00 , "ZFBDT" T_01
WHERE
( T_01 . "MANDT" = :A0 AND T_00 . "FBRNR" = T_01 . "FBRNR" AND T_00 . "FBFNR" = T_01 . "FBFNR" )
AND T_00 . "MANDT" = :A1 AND "DIVISION" = :A2 AND T_00 . "FBSTAT" <= :A3;
On Oracle 9i it ran within 90 seconds and the execution plan was this:
Execution Plan
Plan hash value: 298645010
| Id | Operation                    | Name        | Rows | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT             |             | 1525K|   141M| 5595K (1)| 09:33:38 |
|   1 | NESTED LOOPS                |             | 1525K|   141M| 5595K (1)| 09:33:38 |
|   2 |   TABLE ACCESS BY INDEX ROWID| ZFBINFO     | 9152K|   305M| 97247   (1)| 00:09:59 |
|* 3 |    INDEX RANGE SCAN          | ZFBINFO~B   | 9152K|       | 6121   (2)| 00:00:38 |
|* 4 |   TABLE ACCESS BY INDEX ROWID| ZFBDT       |     1 |    62 |     1   (0)| 00:00:01 |
|* 5 |    INDEX UNIQUE SCAN         | ZFBDT_____0 |     1 |       |     0   (0)| 00:00:01 |
Statistics
          1 recursive calls
          0 db block gets
     302386 consistent gets
      19689 physical reads
After an upgrade to Oracle 10g the statement runs for more than 8 minutes and the execution plan is like this:
Execution Plan
Plan hash value: 4079065069
| Id | Operation                    | Name      | Rows | Bytes |TempSpc| Cost(%CPU)| Time     |
|   0 | SELECT STATEMENT             |           | 1525K|   141M|       |   909K (4)| 01:33:13 |
|* 1 | HASH JOIN                   |           | 1525K|   141M|   410M|   909K (4)| 01:33:13 |
|   2 |   TABLE ACCESS BY INDEX ROWID| ZFBINFO   | 9152K|   305M|       | 97247 (1)| 00:09:59 |
|* 3 |    INDEX RANGE SCAN          | ZFBINFO~B | 9152K|       |       | 6121   (2)| 00:00:38 |
|* 4 |   TABLE ACCESS FULL          | ZFBDT     |    25M| 1535M|       |   716K (4)| 01:13:26 |
Statistics
        495 recursive calls
         66 db block gets
    4709177 consistent gets
    4691042 physical reads
I have asked the SQL Tuning Advisor to tune this statement on Oracle 10g, but it
believes the "TABLE ACCESS FULL" on table ZFBDT is the best way for this statement.
The index ZFBDT_____0 is defined on columns MANDT, FBRNR, FBFNR, so not suprisingly
if I add a hint manually /+INDEX(T_01, "ZFBDT_____0") / then the statement runs 5 times
faster and requires only very few physical and logical reads.
How can I convince the Oracle 10g optimizer to use the primary key index on ZFBDT?
Regards,
Mark

Hello Martin,
the tables ZFBDT and ZFBINFO have got 155 million rows. When
checking the bind variables I can see the condition FBSTAT<=70.
The SQL statement selects only 58000 entries from table ZFBINFO:
FB   COUNT(*)
00          3
10      33151
20       5657
28         28
30      11971
40       1734
50        163
55       5934
72        437
73      17355
74      49113
75      24438
76        529
78     122828
80 139801614
82   11099678
85    3054910
90    1627482
So I say the selection on FBSTAT is really selective.
However, I don't see how manipulating the CBO statistics
(as described in SAP note 724545) would help here.
Regards,
Mark

High-load sql statement using v$sql

Hi,
Can any one please tell me, how do we find high load sql statement and it's user from v$SQL view.
what is the query to find it.
Thank you!

Hello,
You can run ADDM report and check its findings it will tell you tome stuff like the following:
     Finding
67      SQL statements consuming significant database time were found.
40.7      Time spent on the CPU by the instance was responsible for a substantial part of database time.
20.7      Individual SQL statements responsible for significant user I/O wait were found.
13.7      Individual database segments responsible for significant user I/O wait were found.Kind regards
Mohamed Elazab

Tuning tips for sql

Can some one tell me the tuning tips for sql statements, please.
Thanks
Ajwat

Yes get EP (explain plan) going and try add /*+ RULE */ hint to your SIUD commands (Select/Insert/Update/Delete) . This changes the optimizer mode from CHOOSE to RULE, I find RULE uses indexes more often than CHOOSE (see example below).
select /*+ RULE */ c1,c2,c3 from t1 where n1=123
--[EP 1 results]
SELECT STATEMENT Optimizer=HINT: RULE
TABLE ACCESS (BY INDEX ROWID) OF T1
INDEX (RANGE SCAN) OF I_NU_T1_N1 (NON-UNIQUE)
select c1,c2,c3 from t1 where n1=123
--[EP 2 results]
SELECT STATEMENT Optimizer=CHOOSE (Cost=1 Card=1 Bytes=12)
TABLE ACCESS (FULL) OF T1 (Cost=1 Card=1 Bytes=12)
Look for any FULL TABLE SCAN entries in your EP results and try to get rid of them. As the above example shows, switching to RULE uses the index on table T1.
There are a while pile of other HINTS listed as well (other than just RULE) which are at ...
http://download-west.oracle.com/otndoc/oracle9i/901_doc/server.901/a87503/hintsref.htm#4894
There is a whole section on Oracle Performance at the following address...
http://download-west.oracle.com/otndoc/oracle9i/901_doc/server.901/a87503/toc.htm
the Hints section is Chapter 5
There are many more things to tuning tips, but by far, getting your SQL to use indexes is the primary one and you'll have to get EP results to see which indexes are being used (the FREE Toad program shows EP results nicely).
Hope this helps,
Tyler

HOW TO: Post a SQL statement tuning request - template posting

This post is not a question, but similar to Rob van Wijk's "When your query takes too long ..." post should help to improve the quality of the requests for SQL statement tuning here on OTN.
On the OTN forum very often tuning requests about single SQL statements are posted, but the information provided is rather limited, and therefore it's not that simple to provide a meaningful advice. Instead of writing the same requests for additional information over and over again I thought I put together a post that describes how a "useful" post for such a request should look like and what information it should cover.
I've also prepared very detailed step-by-step instructions how to obtain that information on my blog, which can be used to easily gather the required information. It also covers again the details how to post the information properly here, in particular how to use the \ tag to preserve formatting and get a fixed font output:
http://oracle-randolf.blogspot.com/2009/02/basic-sql-statement-performance.html
So again: This post here describes how a "useful" post should look like and what information it ideally covers. The blog post explains in detail how to obtain that information.
In the future, rather than requesting the same additional information and explaining how to obtain it, I'll simply refer to this HOW TO post and the corresponding blog post which describes in detail how to get that information.
*Very important:*
Use the \ tag to enclose any output that should have its formatting preserved as shown below.
So if you want to use fixed font formatting that preserves the spaces etc., do the following:
\   This preserves formatting
\And it will look like this:
   This preserves formatting
   . . .Your post should cover the following information:
1. The SQL and a short description of its purpose
2. The version of your database with 4-digits (e.g. 10.2.0.4)
3. Optimizer related parameters
4. The TIMING and AUTOTRACE output
5. The EXPLAIN PLAN output
6. The TKPROF output snippet that corresponds to your statement
7. If you're on 10g or later, the DBMS_XPLAN.DISPLAY_CURSOR output
The above mentioned blog post describes in detail how to obtain that information.
Your post should have a meaningful subject, e.g. "SQL statement tuning request", and the message body should look similar to the following:
*-- Start of template body --*
The following SQL statement has been identified to perform poorly. It currently takes up to 10 seconds to execute, but it's supposed to take a second at most.
This is the statement:
select
from
         t_demo
where
         type = 'VIEW'
order by
         id;It should return data from a table in a specific order.
The version of the database is 11.1.0.7.
These are the parameters relevant to the optimizer:
SQL>
SQL> show parameter optimizer
NAME                                 TYPE        VALUE
optimizer_capture_sql_plan_baselines boolean     FALSE
optimizer_dynamic_sampling           integer     2
optimizer_features_enable            string      11.1.0.7
optimizer_index_caching              integer     0
optimizer_index_cost_adj             integer     100
optimizer_mode                       string      ALL_ROWS
optimizer_secure_view_merging        boolean     TRUE
optimizer_use_invisible_indexes      boolean     FALSE
optimizer_use_pending_statistics     boolean     FALSE
optimizer_use_sql_plan_baselines     boolean     TRUE
SQL>
SQL> show parameter db_file_multi
NAME                                 TYPE        VALUE
db_file_multiblock_read_count        integer     8
SQL>
SQL> show parameter db_block_size
NAME                                 TYPE        VALUE
db_block_size                        integer     8192
SQL>
SQL> show parameter cursor_sharing
NAME                                 TYPE        VALUE
cursor_sharing                       string      EXACT
SQL>
SQL> column sname format a20
SQL> column pname format a20
SQL> column pval2 format a20
SQL>
SQL> select
2            sname
3          , pname
4          , pval1
5          , pval2
6 from
7          sys.aux_stats$;
SNAME                PNAME                     PVAL1 PVAL2
SYSSTATS_INFO        STATUS                          COMPLETED
SYSSTATS_INFO        DSTART                          01-30-2009 16:25
SYSSTATS_INFO        DSTOP                           01-30-2009 16:25
SYSSTATS_INFO        FLAGS                         0
SYSSTATS_MAIN        CPUSPEEDNW              494,397
SYSSTATS_MAIN        IOSEEKTIM                    10
SYSSTATS_MAIN        IOTFRSPEED                 4096
SYSSTATS_MAIN        SREADTIM
SYSSTATS_MAIN        MREADTIM
SYSSTATS_MAIN        CPUSPEED
SYSSTATS_MAIN        MBRC
SYSSTATS_MAIN        MAXTHR
SYSSTATS_MAIN        SLAVETHR
13 rows selected.Here is the output of EXPLAIN PLAN:
SQL> explain plan for
2 -- put your statement here
3 select
4            *
5 from
6            t_demo
7 where
8            type = 'VIEW'
9 order by
10            id;
Explained.
Elapsed: 00:00:00.01
SQL>
SQL> select * from table(dbms_xplan.display);
PLAN_TABLE_OUTPUT
Plan hash value: 1390505571
| Id | Operation                   | Name     | Rows | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT            |          |     1 |    60 |     0   (0)| 00:00:01 |
|   1 | TABLE ACCESS BY INDEX ROWID| T_DEMO   |     1 |    60 |     0   (0)| 00:00:01 |
|* 2 |   INDEX RANGE SCAN          | IDX_DEMO |     1 |       |     0   (0)| 00:00:01 |
Predicate Information (identified by operation id):
   2 - access("TYPE"='VIEW')
14 rows selected.Here is the output of SQL*Plus AUTOTRACE including the TIMING information:
SQL> rem Set the ARRAYSIZE according to your application
SQL> set autotrace traceonly arraysize 100
SQL> select
2            *
3 from
4            t_demo
5 where
6            type = 'VIEW'
7 order by
8            id;
149938 rows selected.
Elapsed: 00:00:02.21
Execution Plan
Plan hash value: 1390505571
| Id | Operation                   | Name     | Rows | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT            |          |     1 |    60 |     0   (0)| 00:00:01 |
|   1 | TABLE ACCESS BY INDEX ROWID| T_DEMO   |     1 |    60 |     0   (0)| 00:00:01 |
|* 2 |   INDEX RANGE SCAN          | IDX_DEMO |     1 |       |     0   (0)| 00:00:01 |
Predicate Information (identified by operation id):
   2 - access("TYPE"='VIEW')
Statistics
          0 recursive calls
          0 db block gets
     149101 consistent gets
        800 physical reads
        196 redo size
    1077830 bytes sent via SQL*Net to client
      16905 bytes received via SQL*Net from client
       1501 SQL*Net roundtrips to/from client
          0 sorts (memory)
          0 sorts (disk)
     149938 rows processed
SQL>
SQL> disconnect
Disconnected from Oracle Database 11g Enterprise Edition Release 11.1.0.7.0 - Production
With the Partitioning, OLAP, Data Mining and Real Application Testing optionsThe TKPROF output for this statement looks like the following:
TKPROF: Release 11.1.0.7.0 - Production on Mo Feb 23 10:23:08 2009
Copyright (c) 1982, 2007, Oracle. All rights reserved.
Trace file: orcl11_ora_3376_mytrace1.trc
Sort options: default
count    = number of times OCI procedure was executed
cpu      = cpu time in seconds executing
elapsed = elapsed time in seconds executing
disk     = number of physical reads of buffers from disk
query    = number of buffers gotten for consistent read
current = number of buffers gotten in current mode (usually for update)
rows     = number of rows processed by the fetch or execute call
select
from
         t_demo
where
         type = 'VIEW'
order by
         id
call     count       cpu    elapsed       disk      query    current        rows
Parse        1      0.00       0.00          0          0          0           0
Execute      1      0.00       0.00          0          0          0           0
Fetch     1501      0.53       1.36        800     149101          0      149938
total     1503      0.53       1.36        800     149101          0      149938
Misses in library cache during parse: 0
Optimizer mode: ALL_ROWS
Parsing user id: 88
Rows     Row Source Operation
149938 TABLE ACCESS BY INDEX ROWID T_DEMO (cr=149101 pr=800 pw=0 time=60042 us cost=0 size=60 card=1)
149938   INDEX RANGE SCAN IDX_DEMO (cr=1881 pr=1 pw=0 time=0 us cost=0 size=0 card=1)(object id 74895)
Elapsed times include waiting on following events:
Event waited on                             Times   Max. Wait Total Waited
----------------------------------------   Waited ---------- ------------
SQL*Net message to client                    1501        0.00          0.00
db file sequential read                       800        0.05          0.80
SQL*Net message from client                  1501        0.00          0.69
********************************************************************************The DBMS_XPLAN.DISPLAY_CURSOR output:
SQL> -- put your statement here
SQL> -- use the GATHER_PLAN_STATISTICS hint
SQL> -- if you're not using STATISTICS_LEVEL = ALL
SQL> select /*+ gather_plan_statistics */
2 *
3 from
4 t_demo
5 where
6 type = 'VIEW'
7 order by
8 id;
149938 rows selected.
Elapsed: 00:00:02.21
SQL>
SQL> select * from table(dbms_xplan.display_cursor(null, null, 'ALLSTATS LAST'));
PLAN_TABLE_OUTPUT
SQL_ID d4k5acu783vu8, child number 0
select   /*+ gather_plan_statistics */          * from          t_demo
where          type = 'VIEW' order by          id
Plan hash value: 1390505571
| Id | Operation                   | Name     | Starts | E-Rows | A-Rows |   A-Time   | Buffers | Reads |
|   0 | SELECT STATEMENT            |          |      1 |        |    149K|00:00:00.02 |     149K|   1183 |
|   1 | TABLE ACCESS BY INDEX ROWID| T_DEMO   |      1 |      1 |    149K|00:00:00.02 |     149K|   1183 |
|* 2 |   INDEX RANGE SCAN          | IDX_DEMO |      1 |      1 |    149K|00:00:00.02 |    1880 |    383 |
Predicate Information (identified by operation id):
   2 - access("TYPE"='VIEW')
20 rows selected.I'm looking forward for suggestions how to improve the performance of this statement.
*-- End of template body --*
I'm sure that if you follow these instructions and obtain the information described, post them using a proper formatting (don't forget about the \ tag) you'll receive meaningful advice very soon.
So, just to make sure you didn't miss this point:Use proper formatting!
If you think I missed something important in this sample post let me know so that I can improve it.
Regards,
Randolf
Oracle related stuff blog:
http://oracle-randolf.blogspot.com/
SQLTools++ for Oracle (Open source Oracle GUI for Windows):
http://www.sqltools-plusplus.org:7676/
http://sourceforge.net/projects/sqlt-pp/

Alex Nuijten wrote:
...you missed the proper formatting of the Autotrace section ;-)Alex,
can't reproduce, does it still look unformatted? Or are you simply kidding? :-)
Randolf
PS: Just noticed that it actually sometimes doesn't show the proper formatting although the code tags are there. Changing to the \ tag helped in this case, but it seems to be odd.
Edited by: Randolf Geist on Feb 23, 2009 11:28 AM
Odd behaviour of forum software

Error ORA-29900 when tuning spatial sql statement for tuning task

I am trying to tune a SQL statement and getting ORA-29900: operating binding does not exist and PLS-306 wrong number of arguments in call to SDO_FILTER. Oracle Version 11.1.
Query trying to tune:
Select ROUTE_LINK_ID,ROUTE_ID,ROUTE_SYSTEM_ID,ROUTE_SYSTEM_NAME,ASSIGNED_ROUTES_ID,
GEOGRAPHIC_EXTENT_ID,GEOGRAPHIC_EXTENT_NAME,ROUTE_NAME,ROUTE_DIRECTION,FULL_NAME,
OFFICIAL_NAME,ROUTE_LINK_ID,ORDINAL,DISTANCE,RELATIVE_DIRECTION,TRANSPORT_LINK_ID,
GEOMETRY_GA_TW From IDOTLRS.ROUTE_DETAIL A where (ROUTE_SYSTEM_ID=8) AND
MDSYS.SDO_FILTER(A.GEOMETRY_GA_TW, :GeometryFilter, 'querytype=window') = 'TRUE';
Example query with bind variable populated:
Select ROUTE_LINK_ID,ROUTE_ID,ROUTE_SYSTEM_ID,ROUTE_SYSTEM_NAME,ASSIGNED_ROUTES_ID,
GEOGRAPHIC_EXTENT_ID,GEOGRAPHIC_EXTENT_NAME,ROUTE_NAME,ROUTE_DIRECTION,FULL_NAME,
OFFICIAL_NAME,ROUTE_LINK_ID,ORDINAL,DISTANCE,RELATIVE_DIRECTION,TRANSPORT_LINK_ID,
GEOMETRY_GA_TW From IDOTLRS.ROUTE_DETAIL A where (ROUTE_SYSTEM_ID=1) AND
MDSYS.SDO_FILTER(A.GEOMETRY_GA_TW, SDO_GEOMETRY (2003, 1050010, NULL, sdo_elem_info_array (1, 1003, 3), sdo_ordinate_array (288325, 222066, 326949, 245295 )), 'querytype=window') = 'TRUE';
--Tuning Task that throws error ORA-29900
DECLARE
my_task_name VARCHAR2(30);
my_sqltext CLOB;
BEGIN
GeometryFilter := 'MDSYS.SDO_GEOMETRY(2003,1050010,NULL,MDSYS.sdo_elem_info_array(1,1003,3),mdsys.sdo_ordinate_array(288325,222066,326949,245295))';
my_sqltext := 'Select ROUTE_LINK_ID,ROUTE_ID,ROUTE_SYSTEM_ID,ROUTE_SYSTEM_NAME,ASSIGNED_ROUTES_ID, GEOGRAPHIC_EXTENT_ID,GEOGRAPHIC_EXTENT_NAME,ROUTE_NAME,ROUTE_DIRECTION,FULL_NAME, OFFICIAL_NAME,ROUTE_LINK_ID,ORDINAL,DISTANCE,RELATIVE_DIRECTION,TRANSPORT_LINK_ID,GEOMETRY_GA_TW From IDOTLRS.ROUTE_DETAIL A where (ROUTE_SYSTEM_ID=1) AND MDSYS.SDO_FILTER(A.GEOMETRY_GA_TW, :GeometryFilter,''MASK=INSIDE'') = ''TRUE'' ';
my_task_name := DBMS_SQLTUNE.CREATE_TUNING_TASK(
sql_text => my_sqltext,
bind_list => sql_binds(anyData.convertChar('MDSYS.SDO_GEOMETRY(2003,1050010,NULL,MDSYS.sdo_elem_info_array(1,1003,3),mdsys.sdo_ordinate_array(288325,222066,326949,245295))')),
user_name => 'IDOTLRS',
scope => 'COMPREHENSIVE',
time_limit => 240,
task_name => 'lrs_tuning_task_27',
description => 'Task to tune a query on delete');
END;
BEGIN
DBMS_SQLTUNE.EXECUTE_TUNING_TASK( task_name => 'lrs_tuning_task_27' );
END;
any advice would be appreciated to get the tuning task functioning.
thanks in advance.

convertObject allowed EXECUTE_TUNING_TASK to run, but stops with an end of file communication. I need to look and see why.
ORA-03113: end-of-file on communication channel
Process ID: 4676
Session ID: 510 Serial number: 60166
I will try the other option and see what happens.
Will file a bug....
Edited by: Eric Abrams on Sep 27, 2011 7:33 AM
Appears to be logged.
ORA-03113 reported when Enequeueing an ADT which contains a SYS.ANYDATA type [ID 799393.1], unpublished Bug 6830995
Edited by: Eric Abrams on Sep 27, 2011 7:41 AM
Edited by: Eric Abrams on Sep 27, 2011 7:42 AM

SQL Tuning Advisor on a specific SQL statement

Hi all,
How can I used SQL Tuning Advisor in Oracle EM Database Control to tune a specific SQL statement; i.e. the statement is not any of: Top SQL, SQL Tuning Sets, Snapshots Preserved Snapshot Sets.
Thanks in advance,
Ahmed B.

Hi,
You can use either the automatic SQL tuning features that are accessible from Enterprise Manager Database Console on the "Advisor Central" page or trough SQL*PLUS using the DBMS_SQLTUNE pakage:
-- creating the tuning task
set serveroutput on
declare
l_sql_tune_task_id varchar2(100);
begin
l_sql_tune_task_id := dbms_sqltune.create_tuning_task (
                          sql_id      => '<your_sql_id>',
                          scope       => dbms_sqltune.scope_comprehensive,
                          time_limit => 60,
                          task_name   => '<your_tuning_task_name>',
                          description => 'tuning task for statement your_sql_id.');
dbms_output.put_line('l_sql_tune_task_id: ' || l_sql_tune_task_id);
end;
-- executing the tuning task
exec dbms_sqltune.execute_tuning_task(task_name => '<your_tuning_task_name>');
-- displaying the recommendations
set long 100000;
set longchunksize 1000
set pagesize 10000
set linesize 100
select dbms_sqltune.report_tuning_task('<your_tuning_task_name>') as recommendations from dual;For more information, take a look at link provided by Jaffy.
Cheers
Legatti

SQL tuning Advisor for old statements

Hi all,
i've identified SQL ID (through snapshots AWR) that make me performance problem. This is a old select statement (Mar 10, 2008) and when i try to run sql tuning advisor, it shows me this error:
"There was a problem creating a SQL tuning task. ORA-13780: SQL statement does not exist. ORA-06512"
I've set AWR for retain 60 days of Snapshot Retention, why i can't run tuning advisor for this statement??
thanks very much for answers.
Andrea

Hi
The problem is that the information of AWR is based on Historical information that Oracle retrieve of historical tables . AWR means Automatic Workload Repository.
But when you execute the SQL tuning advisor task, Oracle needs retrieve the information of sql statement from SHARED POOL.
The Library Cache is a part of Shared pool and contains an area named SQLAREA that stored information of execution plan for sql statements. This memory area is managed by LRU alghoritm.(last recently used) and the error is produced because this sql statement not is stored in this memory area.
When the sql stament not reside in memory Oracle can't build the execution plan and then the error appear
Regards

SQL Statement tuning

Hi,
Some Sql statement is taking so much time to run. Performance wise it is very slow. How to tune Such SQL statemetns.Would you plase give steps for tuning.
Please any body reply on this...

Hi Satishbabu,
Try to get an PLAN on your sql statement, run EXPLAIN PLAN and check the statistics, if required, try using HINTS and see the difference in the COST.
Can you paste your sql statement in this forum?

How to Run SQL Tuning Advisor on the SQL statement with SQL_ID?

Can you give the steps to run the SQL tuning advisor on the SQL statement with SQL_ID?
Database version: 10g Release 2

Hi,
You can use either the automatic SQL tuning features that are accessible from Enterprise Manager Database Console on the "Advisor Central" page or trough SQL*PLUS using the DBMS_SQLTUNE pakage:
-- creating the tuning task
set serveroutput on
declare
l_sql_tune_task_id varchar2(100);
begin
l_sql_tune_task_id := dbms_sqltune.create_tuning_task (
                          sql_id      => '<your_sql_id>',
                          scope       => dbms_sqltune.scope_comprehensive,
                          time_limit => 60,
                          task_name   => '<your_tuning_task_name>',
                          description => 'tuning task for statement your_sql_id.');
dbms_output.put_line('l_sql_tune_task_id: ' || l_sql_tune_task_id);
end;
-- executing the tuning task
exec dbms_sqltune.execute_tuning_task(task_name => '<your_tuning_task_name>');
-- displaying the recommendations
set long 100000;
set longchunksize 1000
set pagesize 10000
set linesize 100
select dbms_sqltune.report_tuning_task('<your_tuning_task_name>') as recommendations from dual;For more information, take a look at link provided by Jaffy.
Cheers
Legatti

Tuning an sql from a vendor product without modifying the sql statement

Hi,
we have a vendor product which generates SQL Statement. For one query, we get response in 15 seconds. But users are asking if we can bring it down to 5 seconds. Limitation is query can't be changed. It used around 10 to 12 tables and bit complex query.
What kind of options could be evaluated if we want to improve performance of a query (Not sure if it could be ever reduced to 5 seconds)
without making any change to the query.
Database Version: Oracle 10.2.0.4
Thanks,
Sarayu

807778 wrote:
Hi,
we have a vendor product which generates SQL Statement. For one query, we get response in 15 seconds. But users are asking if we can bring it down to 5 seconds. Limitation is query can't be changed. It used around 10 to 12 tables and bit complex query.
What kind of options could be evaluated if we want to improve performance of a query (Not sure if it could be ever reduced to 5 seconds)
without making any change to the query.
Database Version: Oracle 10.2.0.4
Thanks,
SarayuI'd go through the standard stuff of "is there an index that can help?", "should these tables be in a cluster?" etc.. Problem there is that you might degrade other operations, and you might break your application support contract by modifying the schema. Even adding a materialized view could do that.

How to monitor worst performing sql statements

Hi,
I am new to oracle 9i release 2. I come from the Windows world, where we used sql server.
When we performanced tested our product, we always monitor the worst performaning sql statement using the sql profiler. At the end of a 24 hour test, the profiler will list the sql statement with the longest execution time. What is the equivalent Oracle 9i tools that will allow me to monitor the worst performaning sql during a test that lasts between 10 to 24 hours?
Thanks,
Paul0al

Besides statspack and OEM you have a few other options.
If an SQL statement had been identified as performing poorly or a job that you can extract the SQL from then you have the option of explaining all the SQL statements and just reviewing the plans for reasonableness. You can also trace actual execution of the task or individual statemnts (alter session set sql_trace = true for basic 10046 event).
When the SQL has not been identified in advance you can query the shared pool SQL areas for SQL statements that have relatively high physical, logical, or combined IO counts. Then you can perform tuning activities for these statements.
HTH -- Mark D Powell --

Performance tuning in PL/SQL code

Hi,
I am working on already existing PL/SQL code which is written by someone else on validation and conversion of data from a temporary table to base table. It usually has 3.5 million rows. and the procedure takes arount 2.5 - 3 hrs to complete.
Can I enhance the PL/SQL code for better performance ? or, is this OK to take so long to process these many rows?
Thanks!
Yogini

Can I enhance the PL/SQL code for better performance ? Probably you can enhance it.
or, is this OK to take so long to process these many rows? It should take a few minutes, not several hours.
But please provide some more details like your database version etc.
I suggest to TRACE the session that executes the PL/SQL code, with WAIT events, so you'll see where and on what time is spent, you'll identify your 'problem statements very quickly' (after you or your DBA have TKPROF'ed the trace file).
SQL> alter session set events '10046 trace name context forever, level 12';
SQL> execute your PL/SQL code here
SQL> exitWill give you a .trc file in your udump directory on the server.
http://www.oracle-base.com/articles/10g/SQLTrace10046TrcsessAndTkprof10g.php
Also this informative thread can give you more ideas:
HOW TO: Post a SQL statement tuning request - template posting
as well as doing a search on 10046 at AskTom, http://asktom.oracle.com will give you more examples.
and reading Oracle's Performance Tuning Guide: http://www.oracle.com/pls/db102/to_toc?pathname=server.102%2Fb14211%2Ftoc.htm&remark=portal+%28Getting+Started%29

SQL Statements in ABAP and meaning

Hello Friends,
Please, can anybody provide me a documentation on the different ABAP SQL statements and there usage/meanings.
Thanks,
Shreekant

hi,
goto abapdocu->abap Database access->open Sql you will get examples.
for documnetation got se38->specify the command and press F1.
SELECT:
Put the curson on that word and press F1 . You can see the whole documentation for select statements.
SELECT result
FROM source
INTO|APPENDING target
[[FOR ALL ENTRIES IN itab] WHERE sql_cond]
Effect
SELECT is an Open-SQL-statement for reading data from one or several database tables into data objects.
The select statement reads a result set (whose structure is determined in result ) from the database tables specified in source, and assigns the data from the result set to the data objects specified in target. You can restrict the result set using the WHERE addition. The addition GROUP BY compresses several database rows into a single row of the result set. The addition HAVING restricts the compressed rows. The addition ORDER BY sorts the result set.
The data objects specified in target must match the result set result. This means that the result set is either assigned to the data objects in one step, or by row, or by packets of rows. In the second and third case, the SELECT statement opens a loop, which which must be closed using ENDSELECT. For every loop pass, the SELECT-statement assigns a row or a packet of rows to the data objects specified in target. If the last row was assigned or if the result set is empty, then SELECT branches to ENDSELECT . A database cursor is opened implicitly to process a SELECT-loop, and is closed again when the loop is ended. You can end the loop using the statements from section leave loops.
Up to the INTO resp. APPENDING addition, the entries in the SELECTstatement define which data should be read by the database in which form. This requirement is translated in the database interface for the database system´s programming interface and is then passed to the database system. The data are read in packets by the database and are transported to the application server by the database server. On the application server, the data are transferred to the ABAP program´s data objects in accordance with the data specified in the INTO and APPENDING additions.
System Fields
The SELECT statement sets the values of the system fields sy-subrc and sy-dbcnt.
sy-subrc Relevance
0 The SELECT statement sets sy-subrc to 0 for every pass by value to an ABAP data object. The ENDSELECT statement sets sy-subrc to 0 if at least one row was transferred in the SELECT loop.
4 The SELECT statement sets sy-subrc to 4 if the result set is empty, that is, if no data was found in the database.
8 The SELECT statement sets sy-subrc to 8 if the FOR UPDATE addition is used in result, without the primary key being specified fully after WHERE.
After every value that is transferred to an ABAP data object, the SELECT statement sets sy-dbcnt to the number of rows that were transferred. If the result set is empty, sy-dbcnt is set to 0.
Notes
Outside classes, you do not need to specify the target area with INTO or APPENDING if a single database table or a single view is specified statically after FROM, and a table work area dbtab was declared with the TABLES statement for the corresponding database table or view. In this case, the system supplements the SELECT-statement implicitly with the addition INTO dbtab.
Although the WHERE-condition is optional, you should always specify it for performance reasons, and the result set should not be restricted on the application server.
SELECT-loops can be nested. For performance reasons, you should check whether a join or a sub-query would be more effective.
Within a SELECT-loop you cannot execute any statements that lead to a database commit and consequently cause the corresponding database cursor to close.
SELECT - result
Syntax
... lines columns ... .
Effect The data in result defines whether the resulting set consists of multiple rows (table-like structure) or a single row ( flat structure). It specifies the columns to be read and defines their names in the resulting set. Note that column names from the database table can be changed. For single columns, aggregate expressions can be used to specify aggregates. Identical rows in the resulting set can be excluded, and individual rows can be protected from parallel changes by another program.
The data in result consists of data for the rows lines and for the columns columns.
SELECT - lines
Syntax
... { SINGLE }
| { { } } ... .
Alternatives:
1. ... SINGLE
2. ... { }
Effect
The data in lines specifies that the resulting set has either multiple lines or a single line.
Alternative 1
... SINGLE
Effect
If SINGLE is specified, the resulting set has a single line. If the remaining additions to the SELECT command select more than one line from the database, the first line that is found is entered into the resulting set. The data objects specified after INTO may not be internal tables, and the APPENDING addition may not be used.
An exclusive lock can be set for this line using the FOR UPDATE addition when a single line is being read with SINGLE. The SELECT command is used in this case only if all primary key fields in logical expressions linked by AND are checked to make sure they are the same in the WHERE condition. Otherwise, the resulting set is empty and sy-subrc is set to 8. If the lock causes a deadlock, an exception occurs. If the FOR UPDATE addition is used, the SELECT command circumvents SAP buffering.
Note
When SINGLE is being specified, the lines to be read should be clearly specified in the WHERE condition, for the sake of efficiency. When the data is read from a database table, the system does this by specifying comparison values for the primary key.
Alternative 2
Effect
If SINGLE is not specified and if columns does not contain only aggregate expressions, the resulting set has multiple lines. All database lines that are selected by the remaining additions of the SELECT command are included in the resulting list. If the ORDER BY addition is not used, the order of the lines in the resulting list is not defined and, if the same SELECT command is executed multiple times, the order may be different each time. A data object specified after INTO can be an internal table and the APPENDING addition can be used. If no internal table is specified after INTO or APPENDING, the SELECT command triggers a loop that has to be closed using ENDSELECT.
If multiple lines are read without SINGLE, the DISTINCT addition can be used to exclude duplicate lines from the resulting list. If DISTINCT is used, the SELECT command circumvents SAP buffering. DISTINCT cannot be used in the following situations:
If a column specified in columns has the type STRING, RAWSTRING, LCHAR or LRAW
If the system tries to access pool or cluster tables and single columns are specified in columns.
Note
When specifying DISTINCT, note that you have to carry out sort operations in the database system for this.
SELECT - columns
Syntax
| { {col1|aggregate( col1 )}
{col2|aggregate( col2 )} ... }
| (column_syntax) ... .
Alternatives:
1. ... *
2. ... {col1|aggregate( col1 )}
{col2|aggregate( col2 )} ...
3. ... (column_syntax)
Effect
The input in columns determines which columns are used to build the resulting set.
Alternative 1
Effect
If * is specified, the resulting set is built based on all columns in the database tables or views specified after FROM, in the order given there. The columns in the resulting set take on the name and data type from the database tables or views. Only one data object can be specified after INTO.
Note
If multiple database tables are specified after FROM, you cannot prevent multiple columns from getting the same name when you specify *.
Alternative 2
... {col1|aggregate( col1 )}
{col2|aggregate( col2 )} ...
Effect
A list of column labels col1 col2 ... is specified in order to build the resulting list from individual columns. An individual column can be specified directly or as an argument of an aggregate function aggregate. The order in which the column labels are specified is up to you and defines the order of the columns in the resulting list. Only if a column of the type LCHAR or LRAW is listed does the corresponding length field also have to be specified directly before it. An individual column can be specified multiple times.
The addition AS can be used to define an alternative column name a1 a2 ... with a maximum of fourteen digits in the resulting set for every column label col1 col2 .... The system uses the alternative column name in the additions INTO|APPENDING CORRESPONDING FIELDS and ORDER BY. .
http://help.sap.com/saphelp_nw04/helpdata/en/62/10a423384746e8bf5f15ccdd36e8b1/content.htm

Find start and end execution time of a sql statement?

I am have databases with 10.2.0.3 and 9.2.0.8 on HP UNIX 11i and Windows 200x.
I am not in a position to turn on sql tracing in production environment. Yet, I want to find when a sql statement started executing and when it ended. When I look at v$sql, it has information such FIRST_LOAD_TIME, LAST_LOAD_TIME etc. No where it has information last time statement began execution and when it ended execution.. It shows no of executions, elapsed time etc, but they are cumulative. Is there a way to find individual times (time information each time a sql statement was executed. – its start time, its end time ….)? If I were to write my own program how will I do it?
Along the same line, when an AWR snapshot is shown, does it only include statements executed during that snapshot or it can have statements from the past if they have not been flushed from shared memory. If it only has statements executed in the snapshot period, how does it know when statement began execution?

Hi,
For oracle 10g you can use below query to find start and end time, you can see data for last seven days.
select min(to_char(a.sample_time,'DD-MON-YY HH24:MI:SS')) "Start time", max(to_char(a.sample_time,'DD-MON-YY HH24:MI:SS')) "End Time", b.sql_text
from dba_HIST_ACTIVE_SESS_HISTORY a,DBA_HIST_SQLTEXT b where
a.sql_id=b.sql_id
order by 1;
Regards
Jafar

Tuning of Individual SQL statement

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