Which index?

Hi,
I've a view which takes the most rows of a table.
Now i read that if a query takes more than 20% of rows from a table the index don't be used.
This my view:
CREATE OR REPLACE VIEW EULVIS_STROM_STAMM ( INTERNENUMMER,
ANLAGENNUMMER, KUNDENNUMMER, MASTERNUMMER, ANLAGENTYP,
WASSER, ERDGAS, FERNWAERME, ANLAGENSTATUS,
ANLAGENVONDATUM, ANLAGENBISDATUM, ABRECHNUNGSGRUPPE, ANLAGENTITEL,
ANLAGENZUNAME, ANLAGENVORNAME, ANLAGENSTRASSE, ANLAGENHAUSNUMMER,
ANLAGENHAUSNUMMERNERGAENZUNG, ANLAGENPLZ, ANLAGENORT, ANLAGENSTRASSENSCHLUESSEL,
KUNDENTITEL, KUNDENZUNAME, KUNDENVORNAME, KUNDENSTRASSE,
KUNDENHHAUSNUMMER, KUNDENHAUSNUMMERNERGAENZUNG, KUNDENPLZ, KUNDENORT,
AKTUELLETEILZAHLUNG, LETZTEHABENBUCHUNG, DATUMLETZTEHABENBUCHUNG, TAGESSALDO,
DATUMLETZTERECHNUNG, STROMVERBRAUCH, DATUM ) AS SELECT
CAST(GIS_STAMM.INTERNENUMMER AS NUMBER(30, 0)), CAST(GIS_STAMM.ANLAGENNUMMER AS NUMBER(30, 0)), CAST(GIS_STAMM.KUNDENNUMMER AS NUMBER(30, 0)), CAST(GIS_STAMM.MASTERNUMMER AS NUMBER(30, 0)), GIS_STAMM.ANLAGENTYP,
GIS_STAMM.WASSER, GIS_STAMM.ERDGAS, GIS_STAMM.FERNWAERME,
GIS_STAMM.ANLAGENSTATUS, GIS_STAMM.ANLAGENVONDATUM, GIS_STAMM.ANLAGENBISDATUM,
GIS_STAMM.ABRECHNUNGSGRUPPE, GIS_STAMM.ANLAGENTITEL, GIS_STAMM.ANLAGENZUNAME, GIS_STAMM.ANLAGENVORNAME, GIS_STAMM.ANLAGENSTRASSE,
GIS_STAMM.ANLAGENHAUSNUMMER, GIS_STAMM.ANLAGENHAUSNUMMERNERGAENZUNG, GIS_STAMM.ANLAGENPLZ, GIS_STAMM.ANLAGENORT, CAST(GIS_STAMM.ANLAGENSTRASSENSCHLUESSEL AS NUMBER(30, 0)),
GIS_STAMM.KUNDENTITEL, GIS_STAMM.KUNDENZUNAME, GIS_STAMM.KUNDENVORNAME, GIS_STAMM.KUNDENSTRASSE, GIS_STAMM.KUNDENHHAUSNUMMER,
GIS_STAMM.KUNDENHAUSNUMMERNERGAENZUNG, GIS_STAMM.KUNDENPLZ, GIS_STAMM.KUNDENORT, GIS_STAMM.AKTUELLETEILZAHLUNG, GIS_STAMM.LETZTEHABENBUCHUNG,
GIS_STAMM.DATUMLETZTEHABENBUCHUNG, GIS_STAMM.TAGESSALDO, GIS_STAMM.DATUMLETZTERECHNUNG, GIS_STAMM.STROMVERBRAUCH, GIS_STAMM.DATUM
FROM GIS_STAMM
WHERE GIS_STAMM.STROM = 'J'
I've an index of the field STROM and when i analyze a query of my view i see that whole table was used and not the index.
Which index should i use?
Thanks in advance
Nicole

Hello
What will your new table contain? 200000 rows of data, all of which you need to access. Now create an index on that table and...oracle will ignore the index because it will take longer to go to the index to find a row in the table and then go back to the table to get the value than it would to just go through the table from start to finish.
The rationale is, if you are going to be going to every row in the table, you may as well ignore any indexes because they will only slow you down.
If you are looking to access only a few rows in the table, an index can help because it allows oracle to locate the rows you are interested in without having to scan the whole table. But in your case, an index will do nothing other than slow you down
Excuse my ignorace, what is an ACP script? And again, what is the problem with this external program? Is it a program where a user sits and waits for it to complete or is it just a batch type program that does it's work in the background? Other than a view being slow, which really it isn't, you haven't really stated what the problem is you are trying to overcome.
HTH
David

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Which index I should create Btree or Bitmap index?

I have table with columns c1,c2,c3
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the column contain 50% unique values and 50% duplicate values
If Btree why?
If Bitmap Why?
I know that
Btree is used when there more unique values (high cardinality)
Bitmap is used when there less unique values (low cardinality)

read this -
Deadlocks with Bitmap Indexes
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> IDENTIFYING UNUSED INDEXES IN A SQL SERVER DATABASE
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How can i know which index will be used when executing the query ?

1 ) I have query in which i have 3-4 tables but there multiple index on one column .
so how can i know which index will be used when executing the query ?
2) I have a query which ia taking too much time . how can i know which table is taking too much time ?
3) Please Provide me some document of EXplain plan ?

Hi Jimmy,
Consider the below example
/* Formatted on 2011/02/04 21:59 (Formatter Plus v4.8.8) */
CREATE TABLE FIRST AS
SELECT * FROM all_objects;
UPDATE FIRST
SET object_name = 'TEST'
WHERE owner != 'SCOTT';
CREATE INDEX idx_first ON FIRST(object_name);
SELECT *
FROM FIRST
WHERE object_name = 'TEST';
It has not used index
Execution Plan
Plan hash value: 2265626682
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
| 0 | SELECT STATEMENT | | 58678 | 7334K| 163 (4)| 00:00:02 |
|* 1 | TABLE ACCESS FULL| FIRST | 58678 | 7334K| 163 (4)| 00:00:02 |
/* Formatted on 2011/02/04 21:59 (Formatter Plus v4.8.8) */
SELECT *
FROM FIRST
WHERE object_name = 'emp';
This has used the index
Execution Plan
Plan hash value: 1184810458
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
| 0 | SELECT STATEMENT | | 1 | 128 | 1 (0)| 00:00:01 |
| 1 | TABLE ACCESS BY INDEX ROWID| FIRST | 1 | 128 | 1 (0)| 00:00:01 |
|* 2 | INDEX RANGE SCAN | IDX_FIRST | 1 | | 1 (0)| 00:00:01 |
From this we can come to the conclusion that, whether to use one index or not by oracle
would also depend on the data which is present in the table. This has to be this way as
we see in the bind peeking, if oracle sticks to only one plan, say only use the full table
scan, it would be a performance hit when it searches for the second query ie where object_name
='emp';
2.
If we have a query like below.
select * from emp
where upper(ename) = upper(:p_ename);
Evenif we have the index on ename column, oracle wouldn't be able to use the index, as there is a function in the predicate column. If you need oracle to use the index, we need to create a function based index as below.
Create index idx_ename on emp(upper(ename));
Regards,
Cool

Which index will it take and why ?

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Good day Balaji
Prasad
1. How long it took you to write the question in the forum?
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Ronen Ariely
[Personal Site] [Blog] [Facebook]

Which Index is better?

Hi ,
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http://help.sap.com/saphelp_nw04/helpdata/en/e3/e60138fede083de10000009b38f8cf/frameset.htm
http://help.sap.com/saphelp_nw04/helpdata/en/80/1a6473e07211d2acb80000e829fbfe/frameset.htm
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col object_name for a30
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col operation for a35
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set lines 160
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Which index values can be sent to "Insert Into Array" without changing the present array ? E.g. index -1 ?

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Which index to use?

I have a table containing large complete 2D polygons (State and county boundaries). Each row in the table represents an entire polygon rather than a linestring section of a polygon.
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What sort of index should I use to maximise the performance?
I am currently using Fixed Tile Quadtree indexing with an SDO_LEVEL of 6.
Would R-Tree or Hybrid indexing suit such a geometry better?

Hi,
It depends on which version of Oracle Spatial you are using.
As of Oracle 9i, the recommendation is to use R-tree indexes (they are easy to
create, there is no tuning, their performance is nearly always as good or better
than quadtree indexes, they can be geodetic, there is functionality only supported
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Which Index to create on column ?

Hi Guys,
I have a table, which has some no. of columns. In that, one column is of Varchar2(1) which contains the value either 'Y' or 'N' and there are two other columns which contains the sequential numbers and these are unique values. So the data is like below.
Col1     Col2     Col3
1     1     Y
1     2     Y
1     3     N
1     4     N
2     5     N
2     6     Y
2     7     Y
2     8     YThese are the three main columns that will be used in all the queries with other tables, and there scenarios also when only col3 will be used in the queries.
My problem is how do I create index on this table, 1) should I create a Bit map index on Col3 and Btree index on col1 and col2
or 2) I should create btree index on all the three columns.
In case of 1, how the index can be used to improve the performance of the query, do we need to give some hint so that both the indexes are used to execute the statement.
Much appreciate your help.
Thanks in advance.
Vinod.

If this table has frequent concurrent inserts and updates then you should probably stear well clear of a bitmap index.
Presumably you are constraining the unique values with a primary key which means that you're going to have an index on 1 and 2 anyway.
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