Performance Tuning :: Not In Replace With Minus
Sep 15, 2011
I have 2 questions for this SQL Statement for tuning?
select * from a where id not in (select a_id from b)
1- How do i change this query with A MINUS OPERATOR
2- Shall i use a Hint for this query?
Explain plan is:
Execution Plan
--------------------------------------------------------------------------------
Plan hash value: 31652112322
--------------------------------------------------------------------------------
-
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time
|
--------------------------------------------------------------------------------
-
| 0 | SELECT STATEMENT | | 299 | 21528 | 9 (12)| 00:00:01
|
|* 1 | HASH JOIN RIGHT ANTI| | 299 | 21528 | 9 (12)| 00:00:01
|
|* 2 | TABLE ACCESS FULL | b | 1 | 23 | 4 (0)| 00:00:01
|
| 3 | TABLE ACCESS FULL | a | 300 | 14700 | 4 (0)| 00:00:01
|
--------------------------------------------------------------------------------
-
How do i optimize it best?
View 2 Replies
ADVERTISEMENT
Jun 12, 2010
I have a table with:
1 million rows
average row length 200 bytes
50 columns
and this update statement
UPDATE mytable SET varchar2_4000_column = replace(replace(replace...300 times)
It looks at every row in the table (no WHERE clause) and does these 300 replace operations on this column for each row. Each replace replaces with a null so effectively it is removing strings. Much of the time these strings are not in the column.
This update statement takes 25 minutes and it is 98% CPU and 2% USER_IO time.
I figure that is what is taking all the time since it is a CPU bound statement. if rows in this table are persistent over time then tag rows with a flag to show which ones have already been processed and skip these next time around.
View 2 Replies
View Related
Jul 12, 2010
Looking to understand the difference between instance tuning and database tuning.
What is the difference between these two tuning exercises? I understand that an instance is memory based structures (logical) where as database consists of physical structures.
However, how does one tune a database the physical structure? Does it have to do with file placements/block sizes etc. Would you agree that a lot of that is taken care by ASM now in 11g? What tools are required/available (third party as well as oracle supplied) for these types of tuning scenarios?
View 1 Replies
View Related
Jul 16, 2012
How to replace the like operator for increase the performance. Because it is taking more time and not using the index.
SELECT *
FROM emp
WHERE ename like '%AL';
View 30 Replies
View Related
Oct 31, 2011
I have two tables with 113M records in DWH_BILL_DET & 103M in prd_rerate_chg_que and Im running following merge query, which is running for 13 hrs to update records, which is quiet longer time.
SQL> explain plan for MERGE /*+ parallel (rq, 16) */
INTO DWH_BILL_DET rq
USING (SELECT rated_que_rowid,
detail_rerate_flag_code,
rerate_sel_key,
[code].....
View 39 Replies
View Related
Sep 30, 2010
How the length of column width effects index performance?
For example if i had IOT table emp_iot with columns:
(id number,
job varchar2(20),
time date,
plan number)
Table key consist of(id, job, time)
Column JOB has fixed list of distinct values ('ANALYST', 'NIGHT_WORKED', etc...).
What performance increase i could expect if in column "job" i would store not names but concrete numbers identifying job names.
For e.g. i would store "1" instead 'ANALYST' and "2" instead 'NIGHT_WORKED'.
View 24 Replies
View Related
Jun 16, 2010
I have a question about database fragmentation.I know that fragmentation can reduce performance in query times. The blocks are distributed in many extents and scans process takes a long time. Oracle engine have to locate the address of the next extent..
I want to know if there is any system view in which you can check if your table or index has high fragmentation. If it's needed I will have to re-create, move or rebulid the table or index, but before I want to know if the degree of fragmentation is high.
Any useful script or query to do this, any interesting oracle system view?
View 2 Replies
View Related
Oct 20, 2010
There is a simple way to increase the performance of a query by reducing the row-size of the table it hits. I used it in the past by dividing the table into smaller parts and querying respective smaller table in each query.
what is this method called ? just forgot the method and can't recall it. what this type of row-reduction optimization is called ?
View 6 Replies
View Related
Jun 16, 2011
How many records could I have in a single table without performance degradation with Standard Edition without partitioning with cutting-edge server (8 or 12 cores, 72 GB RAM, FC 4 Gbit, etc...) and good storage?
300 Millions in only one table with 500K transactions / day is too much?
Simple database with simple schema.
How many records begin to be too many?
View 2 Replies
View Related
Nov 15, 2010
Testing our 9i to 11g upgrade, we've imported the entire DB into the new machine.We've found that certain procedures are really suffering performance problems. BUT, we've also found, that if we check out a production copy of the procedure from our source code control, and reinstall it, the performance issue goes away. Just alter the procedure and recompiling does NOT work.
The new machine where the 11g database exists is slightly different than the source, but it's not like we have this problem with every procedure. It's only a couple.
any possible reason that we'd have to re-install a procedure to correct a performance problem?
View 13 Replies
View Related
Apr 12, 2013
I need to check the package performance and need to improve the package performance.
1. how to check the package performance(each and every statement in the package)?
2. In the package using the delete statement to delete all records and observed that delete is taking long time to delete all the records in the table(Table records 7000000). This table is like staging table.Daily need to clean the data before inserting the data into it. what can I use instead of Delete.
View 13 Replies
View Related
Aug 9, 2010
Somewhere I read that we should not use hints in Oracle production environments, but we can use hints in the development environment and on achieving the desired execution plan we can adjust the 'statistics' to follow that plan without hints.
Q1. If it is true what statistics do we adjust for influencing the execution plan and how?
For example, I have the following simple query:
select e.empid, e.ename, d.dname
from emp e, dept d
where e.deptno=d.deptno;
emp.empid, emp.deptno and dep.deptno columns have indexes and the tables have the standard structure as found in the basic oracle examples.
If I look at the execution plan of the above query then I see that the driving table is empand the driven table is dept.Also the type of join that is taking place is 'Nested Loop'.
Questions: With respect to the above query,
Q 2. If I want to make dept the driving table and emp the driven table then how can I adjust the statistics to achieve that?
Q 3. If I want to use hash join instead of a nested loop join then then how can I adjust the statistics to achieve that?
I can put the ordered and the use_hash hint to effect this but again I have heard that altering statistics is a more robust way to control an execution plan as compared to hints.
View 6 Replies
View Related
Dec 6, 2011
I have an issue with export(expdp).
When i exporting an user using expdp utility, the load the on the server is going up-to 5. The size of the database is 180GB. Below is the command that i use for export.
expdp sys/xxxx directory=dbpdump dumpfile=expdp_trk_backup.dmp logfile=expdp_trk_backup.log exclude=statistics schemas=trk
Do i need any look into any memory parameters for this?
View 1 Replies
View Related
Oct 17, 2011
The following query gets input parameter from the Front End application, which User queries to get Reports.There are many drop down boxes like LOB, FAMILY, BRAND etc., The user may or may not select values from drop down boxes.
If the user select any one or more values ( against each drop down box) it has to fetch all matching values from DB. If the user does'nt select any values it has to fetch all the records, in this case application will send a value 'DEFAULT' (which is not a value in DB ) so that the DB will fetch all the records.
For getting this I wrote a query like below using DECODE, which colleague suggested that will hamper performance.From the below query all the variables V_ are defined in procedure which gets the values selected by user as a comma separated string here V_SELLOB and LOB_DESC is column in DB.
DECODE (V_SELLOB, 'DEFAULT', V_SELLOB, LOB_DESC) IN
OPEN v_refcursor FOR
SELECT /*+ FULL(a) PARALLEL(a, 5) */
*
FROM items a
WHERE a.sku_status = 'A'
[code]...
View 9 Replies
View Related
Sep 3, 2010
what the principal things to look at when we have for the same query different performance results are?I have 2 different bases: the plan and data are the same but performance results are very differents.
View 10 Replies
View Related
Mar 17, 2012
are the most important performance keys we have to calculate or take in account to preserve or to increase the DB performance in terms of response times, and whatsoever according to performance ?
View 8 Replies
View Related
Jul 16, 2010
I have 70 materialized views where I need to replace the FROM SCHEMA1 TO FROM SCHEMA2...To quickly to do the fix for all the 70 views..
SELECT REPLACE (QUERY, 'schema1', 'schema2' )FROM USER_MVIEWS ;
But It throws me an error that Number cannot be replace.
View 14 Replies
View Related
Nov 29, 2011
I got a two tables, table the_table_1 consist of customers and the other one the_table_2 consist of channels.
And I need to get list of channels by contract which are an assigned to customers.
The select below give me a only assigned channels but I need to get a contract_key too from the_table_1.
select o.channel_name from the_table_2 o
minus
select o.channel_name from the_table_1 a, the_table_2 o
where a.contract_key=237092201
and a.offer_channel_key=o.OFFER_CHANNEL_KEY
And the select under (after minus) gives a list of non assigned channels by contract_key:
select o.channel_name from the_table_1 a, the_table_2 o
where a.contract_key=237092201
and a.offer_channel_key=o.OFFER_CHANNEL_KEY
how to rewrite a select to get required result?
View 2 Replies
View Related
Sep 28, 2011
I am looking for an explanation for having the following query:
SELECT PK_SERIAL_NUMBER FROM TABLE1 MINUS (SELECT FK_SERIAL_NUMBER FROM TABLE2);
Which normally returns the values of SERIAL_NUMBER that are not passed to the child table TABLE2
and the query:
SELECT PK_SERIAL_NUMBER FROM TABLE1 WHERE PK_SERIAL_NUMBER
NOT IN
(
SELECT FK_SERIAL_NUMBER FROM TABLE2
);
which returns 0 rows!
View 6 Replies
View Related
Feb 12, 2013
I have a two tables with same column name , I wanted to find different record in table1 when compared with table2
create table table1(col1 number,col2 number,col3 number,col4 number,col5 number);
create table table2(col1 number,col2 number,col3 number,col4 number,col5 number);
insert into table1 values(1,2,NULL,NULL,NULL);
insert into table2 values(1,2,NULL,NULL,NULL);
commit;
select col1 from (select col1,col2,col3,col4,col5 from table1 minus select col1,col2,col3,col4,col5 from table2);
no rows selected
how come i get no rows selected when col3,col4,col5 is having null values but NULL could be anything so
NULL-NULL cannot be equal to zero how is it possible
View 3 Replies
View Related
Mar 27, 2013
I am working on an assignement where client is using Oracle 10g but stuck to using RBO Now the application team, from the GUI available to them build dynamic queries and some of them run very slow.
Neither the code can not be changed to tune the queries nor do we get the exact step in the plan which is an issue (being RBO).For some long running queries the Tuning advisor is not producing any recommendations.
Another hurdle is that all the application users are using same application user id so we can not write a logon trigger to use CBO for some particular queries to see what is happening in the background!
View 11 Replies
View Related
Jul 4, 2012
I want to tuning the next sql sentence. In this sql I want to get the hash_value and sql_text of the sentences that it's causing TX blocks. Is it possible?. This sentence works fine but sometimes It's slow.
SELECT DISTINCT hash_value,
sql_text
FROM gv$sql sq
WHERE hash_value IN (SELECT DISTINCT prev_hash_value
FROM gv$session se
WHERE sid IN (SELECT sid
FROM gv$lock l
WHERE type = 'TX'
AND ctime >= 2000
AND l.inst_id = se.inst_id
AND l.sid = se.sid)
AND sq.inst_id = se.inst_id);
[code]....
View 7 Replies
View Related
Nov 2, 2012
I see one of my SQL's which is ran by the user on a 10.2.0.3 database changing its SQL_ID after some runs even if the query is not changed a bit! However the HASH VALUE for this query remains the same.
how a same query can have different SQL_ID's but same HASH_VALUE?
Note: Statistics are not modified on the base tables of this query.
View 10 Replies
View Related
Aug 10, 2011
I am running Oracle 10.2.0.1.0 on MS Windows 2003 server 64-bit with 16G RAM.
Here is the findings for my Oracle database.
SQL> select * * from v$sgainfo;
NAME BYTES RES
-------------------------------- ---------- ---
Fixed SGA Size 1293560 No
Redo Buffers 7094272 No
Buffer Cache Size 830472192 Yes
[code]...
I find that the SGA component "Buffer Cache" is decreasing from the start "1.8G" and down to now 0.8G. On the other hand, the component "Shared Pool" is increasing from the start 0.3G to now 1.2G. I noticed that there are 100 operations of shrinking of "Buffer cache" and growth of "Shared Pool" in Oracle every day.Is it a indicator that I should raise up the SGA_MAX_SIZE?
I tried to increase the SGA_MAX_SIZE to 4G. But I cannot start the Oracle afterward.Is it a limitation of MS Windows(OS) or Oracle?I set the SGA_MAX_SIZE to 3G. This time, I can startup Oracle.What is the optimum/maximum I can set to SGA_MAX_SIZE?Is there any adverse effect/concern when setting the SGA_MAX_SIZE more than 2G?
View 6 Replies
View Related
Jul 11, 2012
Here i have three tier application. I want to know it host name from sid or sqlid . I want to know which query run on which host. Because i have one user from application to database. So i want to know which query consume more time on which host ?
View 19 Replies
View Related
Mar 17, 2006
How can I disable redo generation for DML statements.
View 25 Replies
View Related
Jul 26, 2011
I am getting enq: TS - contention as top event in AWR Report.where can i look into database to fix this issue.
View 14 Replies
View Related
Aug 14, 2010
I want to run some OLTP benchmarks on my system. I have looked up the TPC-E benchmarking suite .. but the documentation on the site makes no sense to me .
View 1 Replies
View Related
Nov 19, 2011
where difference lies between these operators or clause, & whether there is any "except" operator in oracle, i know other three are used bt dont think oracle uses "except" too..as far as i have seen "NOT IN", "MINUS" , "NOT EXISTS" are exactly similar?
View 4 Replies
View Related
Dec 1, 2010
I wish to delete records found with function MINUS from file1, which is a result of records not found in file2.
Both codes are taken way too long.
ps. none of the columms are unique, and some records have no value in some columns
DELETE
FROM file1 y
WHERE EXIST (SELECT *
FROM (
SELECT a.col1, a.col2, a.col3, a.col4
FROM file1 a
[Code]....
View 38 Replies
View Related
