Performance Tuning :: Creating Normal / Composite Indexes On Fields
Feb 14, 2013
I Want to tune the attached query. I have tried by creating the normal indexes and composite indexes on the fields . I feel that , Only normal index is required for this instead of composite index?
11:15:19 SQL> @slot.sql
11:16:03 SQL>
11:16:03 SQL> drop table slot purge;
Table dropped.
Elapsed: 00:00:00.05
11:16:03 SQL>
11:16:03 SQL> create table slot
11:16:03 2 (
11:16:03 3 id varchar2 (40) not null,
[code]....
- dynamic sampling used for this statement
22 rows selected.
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May 12, 2011
I have created an non unique index lk_fein on lookup_fein( code,map_id,trash). When I check the explain plan it does a full table scan on lookup_fein. if I force it to use index by it does and the cost also decreases.
SQL> SELECT WORK_FEIN,
2 NON_FEIN ,
3 FI_FEIN ,
4 MFEIN ,
5 TOTAL_FEIN ,
[code]...
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Dec 10, 2010
So I was reading about indexes here:[URL]...1Is there any reason to NOT use an index? If there aren't, then should you use an index on every column on every table?
What is the general best practice with indexes? After reading the section, it seems that there are only positive impacts of using an index, so why are they not automatically created?
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Sep 26, 2012
what analyzing a table does to existing indexes? Do I need to rebuild the indexes after dbms_stats.gather_table_stats command ?
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May 20, 2011
Below query is getting delayed becasue of BitMap Indexes on the table. I am trying to avoid indexes by using Hints in the query but unable to do so, Details are as follows.
explain plan for
SELECT cbu_cid, cbu_cid_customer_en_nm,
COUNT (billg_acct_no) AS billg_acct_no,
SUM (subscriber_cnt) AS subscriber_cnt
FROM daily_view
WHERE (billg_system_id = 'TM' AND mktg_sub_segment_a_nm = 'TM')
AND (cbu_cid NOT IN ('0001988048', '0001379962', '0001350469'))
GROUP BY cbu_cid, cbu_cid_customer_en_nm
HAVING SUM (subscriber_cnt) > 10
ORDER BY subscriber_cnt DESC;
[code]....
I have tried with ALL_ROWS & PARALLEL.how to avoid above two indexes in a query.
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Jan 12, 2011
So our situation is pretty simple. We have 3 tables.
A, B and C
the model is A->>B->>C
Currently A, B and C are range partitioned on a key created_date however it's typical that only C is every qualfied with created date. There is a foreign key from B -> A and C -> Bhave many queries where the data is identified by state that is indexed currently non partitioned on columns in A ... there are also indexes on the foreign keys that get from C -> B -> A. Again these are non partitioned indexes at this time.
It is typical that we qualifier A on either account or user or both. There are indexes (non partitioned on these) We have a problem with now because many of the queries use leading wildcards ie. account like '%ACCOUNT' etc. This often results in large full table scans. Our solution has been to remove the leading wildcard.
We are wondering how we can benefit from partitioning and or sub partitioning table A. since it's partitioned on created_date but rarely qualified by that. We are also wondering where and how we can benefit from either global partitioned index or local partitioned indexes on tables A. We suspect that the index on the foreign key from C to B could be a local partitioned index.
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Aug 16, 2012
getting all indexes script in particular schema.
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Sep 27, 2013
I have tried a lot by alternate solutions like rearranging the order of tables in join and moving where conditions before but no success...Its a bottleneck and I could not have indexes on these tables in production...I want to change the approach in subquery
SELECT
g.COLUMN1,
g.COLUMN2,
e.COLUMN3,
g.COLUMN4,
MIN(e.dat1) KEEP ( DENSE_RANK FIRST ORDER BY date2 Desc) * -1,
min(to_char(date3,'dd-mm-yyyy'))
[code]....
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Jun 1, 2012
I don't have any dba privileges, can you share a scripts which can tell how many block my query is fetching with or without indexes. How do i also get buffer hit, how can i get i/o without sql trace as i don't have access to dump_dest
I have a below query
SELECT DISTINCT ser_id AS STA_ser_id, rct_name AS STA_name
FROM sd_servicecalls, rep_codes, rep_codes_text
WHERE ser_sta_oid = rcd_oid
AND rcd_oid = rct_rcd_oid
AND rct_name IN ('New', 'Awaiting Approval', 'Approved', 'In Progress', 'Awaiting Supplier', 'Awaiting RFC', 'Awaiting Release', 'Pending Release', 'On Hold', 'Resolved', 'Implemented', 'Closed');
Does large hash value in explain plan mean more resource needed and more time to execute the query, How can i use ADDM for the above sql.
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Mar 19, 2012
getting how many local and global indexes on particular oracle table
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Mar 29, 2004
I am having Oracle 9i relaese 2 on my db server. I am getting the following error every time I try to create a bitmap index:-
ORA-00439: feature not enabled: Bit-mapped indexes
I have queried the v$option table .Here the value of parameter Bit-mapped indexes is FALSE.
The result of v$version is :-
Oracle9i Release 9.2.0.1.0 - 64bit Production
PL/SQL Release 9.2.0.1.0 - Production
CORE 9.2.0.1.0 Production
TNS for Solaris: Version 9.2.0.1.0 - Production
NLSRTL Version 9.2.0.1.0 - Production
Actually when we created the database our installation was halted . so we manually created the database using Create database command.
How can we enable the BITMAP Index Feature now.
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Feb 4, 2005
16:28:32 SQL> create bitmap index bp_idx_ag_id on transactions(type);
create bitmap index bp_idx_ag_id on transactions(type)
*
ERROR at line 1:ORA-25122: Only LOCAL bitmap indexes are permitted on partitioned tables
how to create bitmap index on partitiioned tables
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Apr 5, 2012
Create small functional indexes for special cases in very large tables.
When there is a column having one values in 99% records and another values that have to be search for, it is possible to create an index using null value. Index will be small and the rebuild fast.
Example
create index vh_tst_decode_ind_if1 on vh_tst_decode_ind
(decode(S,'I','I',null),style)
It is possible to do index more selective when the key is updated and there are many records to create more levels in b-tree.
create index vh_tst_decode_ind_if3 on vh_tst_decode_ind
(decode(S,'I','I',null),
decode(S,'I',style,null)
)
To access the record can by like:
SQL> select --+ index(vh_tst_decode_ind_if3)
2 style ,count(*)
3 from vh_tst_decode_ind
4 where
5 decode(S,'I','I',null)='I'
6 group by style
7 ;
[code]....
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Dec 9, 2010
I have a view on base tables holding historical data for previous 60 months(one table per month) with union all operators.create index on those base tables will improve performance or creating a primary key with disabled novalidate will improve for retrieving data?
The view has around 8 million data and used as a fact table with 4 dimension tables.A DTS package from MSSql side refreshes OLAP cube by retrieving data from these tables in oracle.
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Apr 15, 2013
how would we learn creating workspaces on the production server for application services:
* Folder structure
* How client workspaces are sharing other common folders, tomcat, java, software release etc
* Scripts tomcat and create54workspace
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Jul 3, 2013
I have a table say MY_TAB with columns as below
emp_id number,
name varchar2(30),
from_dt date,
remarks varchar2(60)
insert into MY_TAB values (1,'TOM','01-JAN-13', 'some remark');
insert into MY_TAB values (1,'TOM','02-JAN-13', 'some remark');
insert into MY_TAB values (2,'TOM','01-JAN-13', 'some remark');
insert into MY_TAB values (3,'TOM','01-JAN-13', 'some remark');
insert into MY_TAB values (4,'TOM','01-JAN-13', 'some remark');
insert into MY_TAB values (4,'TOM','02-JAN-13', 'some remark');
How do I ensure that when a user tries to insert record with emp_id as 1, then he should only be allowed to enter another from_dt but the value in the name column have to be the same as in the previous row of emp_id 1.
insert into MY_TAB values (1,'TOOM','03-JAN-13') --shld not be allowed.
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Nov 8, 2012
I have a lot of queries on a table with WHERE clause:
WHERE CR_DATE > :y AND CR_VALUE = :x
Actually, there is an index on (CR_DATE) but much more selective index is on (CR_DATE, CR_VALUE). If I do not UPDATE any records on this table, is there any difference in INSERT operation (or another problem) when I replace actual index with multi-column index?
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Jan 14, 2013
Can we tune below mentioned query without creating any indexes :
SELECT /*+ PARALLEL(a,64) */x_abc_41, x_abc_44, CALLED_FROM_NUM, X_abc_25, created, evt_stat_cd, last_date, x_abc_number_from,
x_abc_complete_date
FROM table a
WHERE a.todo_cd in('MNPIN','MNPOUT')
AND a.x_abc_25 = 'NP RFS'
AND a.created BETWEEN sysdate-180 AND sysdate
Explain Plan :
PLAN_TABLE_OUTPUT
Plan hash value: 3718629559
----------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | TQ |IN-OUT| PQ Distrib |
----------------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 11 | 2376 | 9462 (4)| 00:02:51 | | | |
[code]...
Note : Currently this query is taking 3 Minutes for retrieving 8000 records,But should be executed in less than 1 min.
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Mar 16, 2010
Lot of my tables are just for join purpose , a table with just with two columns both FK , I did not add any composite PK to this table, lot my queries uses this table , because it does not have composite PK will the query be slow ? what I have to do to increase performance querying with such tables ?
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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?
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Nov 10, 2010
I did a search on this topic and did see the ASK TOM response that storing all varchar2 fields as (2000) or what not is a bad idea based on an array fetch that developers may use etc. However I'm not sure that applies to my specific question, and the other examples he gave certainly didn't apply. So I'll pose the question a different way:
Question #1: Is there, for example, a performance difference between setting a field as varchar(2000) and varchar(25) if I was just running a native SQL query using a front end tool like TOAD?
Question #2: If I also need to index that field, will it take longer to index a varchar(2000) field than a varchar(25) field, assuming the same data is in both fields?
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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].....
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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'.
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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?
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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 ?
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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?
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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?
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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.
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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.
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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?
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