How bit map index works?

I am not getting an example for bitmap index mechanism.
Supposing their is a table T1 with column c1 having records
Y
N
N
Y
Y
N
and i query the table like
select * from t1 where c1 = 'Y'
How bit map index functions?
thanks,
Vinodh

I think you should check the google's new feature to explore -> [How bitmap Index Works|http://www.google.co.in/search?hl=en&rlz=1G1GGLQ_ENIN333&q=how+bitmap+index+works&meta=&aq=0&oq=how+bitma]
Regards.
Satyaki De.

Similar Messages

How to set the option Bit-mapped indexes to true ?

Hi,
I a not a an Oracle Administrator. Usually, I just use Oracle as developper. I have got a Oracle 10g database. I can not import data in my database because the Bit-mapped options is not set.
When I type
select banner from v$version
I get this result :
BANNER
Oracle Database 10g Release 10.2.0.1.0 - Production
PL/SQL Release 10.2.0.1.0 - Production
CORE 10.2.0.1.0 Production
TNS for Linux: Version 10.2.0.1.0 - Production
NLSRTL Version 10.2.0.1.0 - Production
I run the import and I get this error :
IMP-00017: following statement failed with ORACLE error 439:
"CREATE BITMAP INDEX "ID_ACC_DO" ON "ES_AUDIT_CONNEXION_ARCH" ("DATE_OUVERTU"
"RE" ) PCTFREE 10 INITRANS 2 MAXTRANS 255 STORAGE(INITIAL 33554432 FREELIST"
"S 1 FREELIST GROUPS 1 BUFFER_POOL DEFAULT) TABLESPACE "IND_XL" LOGGING"
IMP-00003: ORACLE error 439 encountered
ORA-00439: feature not enabled: Bit-mapped indexes
I typed the command :
SELECT * FROM V$OPTION WHERE PARAMETER LIKE 'Bit-mapped%';
I get the result :
PARAMETER
VALUE
Bit-mapped indexes
FALSE
How to set this parameter to true ?
Best regards,
Xavier

I beleiev that you are on Standard Edition.Bitmap indexes can be used only when you are working with Enterprise edition.
SQL> select * from V$option where parameter like '%Bit%';
PARAMETER
VALUE
Bit-mapped indexes
TRUE
SQL> select * from V$version;
BANNER
Oracle Database 11g *Enterprise Edition* Release 11.1.0.6.0 - Production
PL/SQL Release 11.1.0.6.0 - Production
CORE 11.1.0.6.0 Production
TNS for 32-bit Windows: Version 11.1.0.6.0 - Production
NLSRTL Version 11.1.0.6.0 - Production
SQL>I guess you see the entry coming of Enterprise Edition in my banner.This is missing in your V$version, so you are using Standard Edition install.
You need to move to Enterprise edition to use Bitmap Indexes.
HTH
Aman....
Edited by: Aman.... on Dec 11, 2008 3:09 PM
added a little more.

Creating a bit map index on a partitioned table

Dear friends,
I am trying to create a bitmap index on a partitioned table but am receiving the following ORA error. Can you please let me know on how to create a local bit map index as the message suggests?
ERROR at line 1:
ORA-25122: Only LOCAL bitmap indexes are permitted on partitioned tables
Trying to use the keyword local in front leads to wrong syntax.
Thanks in advance !!
Somnath

ORA-25122 Only LOCAL bitmap indexes are permitted on partitioned tables
Cause: An attempt was made to create a global bitmap index on a partitioned table.
Action: Create a local bitmap index instead
Example of a Local Index Creation
CREATE INDEX employees_local_idx ON employees (employee_id) LOCAL;
Example is about btree and I think it will work for bitmap also.

Table name where I can see the Secondary bit map Index for Cube Loads in BI

Hello Friends I want to know the table name where I can see the Secondary bit map Index that gets created with each request that get loaded to Cube so each 1 request will be multiplied by 7 dimension and 7x1 = 7 local secondary bit map index will be created where is that table which show me that .
Under Oracle every uncompressed request corresponds to one partition in the
F facttable of the corresponding infocube. This partition also brings along
a full set of secondary local bitmap index partitions.
If you have a cube with 10 uncompressd requests and 10 dimensions (every
dimension brings with it a local bitmap index) you have 100 partitions for
the table itself and 10 x 10 index partitions which makes a total of
100 database objects. where is that table in BI WHICH STORE THIS INFORMATION
Also if I have E Table with no entries for future 2009 dentries will that be an issue with blank partition ion E Fact table if yes please suggest how to resolve this issue

Hi Soniya
Information about BI objects is stored in the RSD* tables. For example:
Infocubes: RSDCUBE / RSDCUBET
Aggregates: RSDDAGGR_V / RSDDAGGRT
You can see information on abap dictionary object as well in transactions SE11 / SE14. You will have to know the real table name of the cube, should be something like /BIC/F* for the uncompressed and /BIC/E* for the compressed table.
Best regards, Michael

Bit Map Indexing

Hi All
i have a table with 5.5 million records and i have a fields (project id and owner id) with 8400 and 507 distinct values. For reporting reasons i want to create a bit map index on the project id. My question is even though it makes the query faster will it take more space? How can i calculate how much space it takes? Secondly if the ROI is not good for creating index on the project id can i creat index on the second field (owner id) and can still make the query faster?
Thanks

897837 wrote:
i have a table with 5.5 million records and i have a fields (project id and owner id) with 8400 and 507 distinct values. For reporting reasons i want to create a bit map index on the project id. My question is even though it makes the query faster will it take more space? Strange question - indexes are an overhead. Space is needed for an index structure. The structure needs to be maintained when data is added, changed or deleted.
The question is whether these overheads are justified by the increase in performance when reading the table structure for selected rows and using the index structure as part of process to get to those selected rows.
So it is not only space that is the coin of payment for indexes. There's also extra CPU to burn in order to maintain those indexes.
How can i calculate how much space it takes? Well, today I would say that space is much less of a consideration. Disk space is cheap. Overheads to maintain additional data structures are not cheap. So I would first look at the performance impact. If you need to maintain a 100 rows/sec insert rate for example, you can ill afford overheads that do not pay back with time gained when reading data.
I would also want to measure just how much the index reduces the workload for reading data. Does it decrease the read I/O load by 1% or 50% ?
You need to quantify the impact of that index to determine whether it is worthwhile. And it does not mean merely calculating the cost ito space used and then see how fast it makes a query by using a stop watch or timer (the wrong metric for measuring SQL performance).

Bit Map index in DW application

Hi
I have a DW database having a table contains 9 million records. Normally for DW application bit map index is preffered if the cardinality is low.
I want to create an index on one of the column having the cardinality is about millions, so which index is preferrable?. If I go with normal indexing any performance degradation will be happen for the application? or if I used bit map indexing any improvement will be there?
Many thanks

I would go for normal index, there is a certain additional load when inserting, updating, deleting, but in that case a bitmapped index wouldn't be good idea anyway.

Bit-mapped Index

Hi,
I run this
CREATE BITMAP INDEX bx_time_period ON time_period (time_period_cd)
and i got this error:
ORA-00439: feature not enabled: Bit-mapped
I am using a Oracle 9i SE.
How can i do to fix this error ?
Do i need to install any patch
Thanks.
Leo

About differences between normal an bitmap indexes you can see [url http://download-west.oracle.com/docs/cd/B14117_01/server.101/b10743/schema.htm#sthref883]The documentation
In general, bitmap indexes are useful in application with huge data, low cardinality keys and low level of concurrent transactions (i.e. DataWarehouse), while normal indexes are tipically suitable for OLTP applications.

How do Map files work with a Windows application?

I need confirmation on how map files work.
I have created a map file previously and have updated the HTML help with a few new topics and changed the Title on a handfull of topics.
The map file setup is done for the new topics, but I am thinking I need to "fix" those topics whose title has changed.
I have opened the Map.h file I created and looked at the references, for simplicity sake lets say it looks like this:
#define Dials_Setup 1
#define Project_Setup 2
#define Scenario Scenario_Setup 54
I assume the mapping process goes like this:
(1) I hand off map file and the CHM help file
(2) Developer addes the ID of "2" to the Project Setup window form
(3) When the user is on the Project Setup window, they press F1
(4) The Project Setup window form gets the ID of "2"
(5) The Map.h file translates the "2" to "Project_Setup" topic title
(6) The CHM is opened to the topic with a title of "Project_Setup"
So, if I changed the title of the topic from "Project_Setup" to "Project_Setup_Window" would I have to update the line item in the Map.h file from "Project_Setup" to "Project_Setup_Window" for the mapping to work and the client to see the correct topic when the press F1?
I am thinking these all need to be in sync between the Map.h file and the CHM file.
As always, thanks for any guidance.
Michael F Weart

Hi, Michael
You have it right - basically. I'll just add a few notes.
Yes. Typically you would give the .h and the .chm file to the developer. However, sometimes the developer will give you a .h file created from their IDE tool (e.g., Visual Studio). In that case, you would Import the .h file into your RoboHelp project and map it that way. Or it can be a combination as long as there are no duplicates of Map #s or Context IDs. Another tip: You can also generate a Map File Report (Tools > Reports > Map IDs) which can be a handy guide for the developer.
Note: The alphanumeric string for the Context ID (sometimes also called a Topic ID) does not necessarily have to be formed from the Topic Title. The reason it may seem that way is because RoboHelp uses the Topic Title as a matter of convenience to help you keep track of the which topic is being mapped. The main thing is that there are no duplicates and RoboHelp has a report for that as well. In Microsoft HTML Help (.chm), the actual mapping from the .h Map # to the URL of the actual topic can be found in the .ali (alias) file which can be found in your Project root. The .ali file is compiled into the .chm itself.
Here is a good Online Help topic with more details:
http://help.adobe.com/en_US/robohelp/robohtml/WS5b3ccc516d4fbf351e63e3d11aff59c571-7ff9.ht ml
Rob Chandler has really good documentation for Microsoft HTML Help which you will find here:
http://helpware.net/htmlhelp/how_to_context.htm
John Daigle
Adobe Certified RoboHelp and Captivate Instructor
Evergreen, Colorado
www.showmethedemo.com

Bit map indexes.

Hi-
I am trying to understand the below from oracle documentation. Can someone explain the EXPLAIN PLAN for the below in simpler way. Thanks
Viewing Bitmap Indexes with EXPLAIN PLAN
Index row sources using bitmap indexes appear in the EXPLAIN PLAN output with the word BITMAP indicating the type of the index. Consider the sample query and plan in Example 12–8.
Example 12–8EXPLAIN PLAN with Bitmap Indexes
EXPLAIN PLAN FOR
SELECT * FROM t
WHERE c1 = 2
AND c2 <> 6
OR c3 BETWEEN 10 AND 20;
explain plan
SELECT STATEMENT
TABLE ACCESS T BY INDEX ROWID
BITMAP CONVERSION TO ROWID
BITMAP OR
BITMAP MINUS
BITMAP MINUS
     BITMAP INDEX C1_IND SINGLE VALUE
     BITMAP INDEX C2_IND SINGLE VALUE
BITMAP INDEX C2_IND SINGLE VALUE
BITMAP MERGE
BITMAP INDEX C3_IND RANGE SCAN
In this example, the predicate c1=2 yields a bitmap from which a subtraction can take
place. From this bitmap, the bits in the bitmap for c2 = 6 are subtracted. Also, the bits in the bitmap for c2 IS NULL are subtracted, explaining why there are two MINUS row sources in the plan. The NULL subtraction is necessary for semantic correctness unless the column has a NOT NULL constraint. The TO ROWIDS option generates the rowids
necessary for the table access.
Thanks
sk
Edited by: sk12345678 on Dec 10, 2011 7:45 PM

WHY ORACLE TALKS OF MINUSminus in the sense of the set operator *the set { {A} minus } is the set of all elements members of {A} that are not members of {B}*
<font face="courier">
           ┌───────────────┐
┌──────────┼───┐           │
│          │   │           │
│ C1 = 2   │   │  C2 = 6   │
│          │   │           │
└──────────┼───┘           │
           └───────────────┘
</font>
{C1 = 2} and {C2 != 6} ≡ {C1 = 2} minus {C2 = 6} ≡ {C1 = 2} intersect {C2 != 6} ≡ {C1 = 2} intersect complement({C2 = 6})
{1,2,3} minus {2,3,4,5,6} gives {1}True
instead should be an INTERSECTION of {1,2,3} and {2,3,4,5,6}False ( you missed the not )
an INTERSECTION of {1,2,3} and {1,7,8,9} ( you missed the not )
Regards
Etbin

Bit Map Index

how to use BitMap index and function based index.
in Oracle how its executed. how its taking data fast ??

@Prasad: lower(ename) is function based index.Like Hydrabadi Biriyani.... :)
@OP: Read the Oracle Documentation about Indexes.

ORA-00439: feature not enabled: Bit-mapped indexes

Do I need to change any parameter to enable this feature or I just can't use it in Oracle XE?
Thanks,
Allwyn

Hi Allwyn,
the feature list of XE says that Bitmapped index and bitmapped join index are not supported ( http://download-east.oracle.com/docs/cd/B25329_01/doc/relnotes.102/b25327/toc.htm#BEIDGBCD ) . I guess it won't work then.
We get the function based index, though.
Regards,
~Dietmar.

How index Works.

Hi all,
Shall i know how the indexes work internally in Oracle database. Because when we are creating index in some fields, its slows down the speed of the query, and when creating some indexes speeds up the index.
So please help me How to determine the fields, in which i have to create index and in what basis.
Thanks and Regards,
Manu.

Index are reference to data in tables's columns on what they are based. Index work exactly in way like we have book's index describing its chapters and what page # chapter can be found.
They only contain reference to the data. There are two types on index.
B-tree index and bit map indexes.
Whenever new index created on column it stores column value and rowid of that row into the index. The index maintains all the values in the tree structure. i.e. if you create index on salary column (supose salary column contain the salary range 1000) in that case half of the branch on one side contain values upto 1 to 500 and on another side 501 to 1000. again 1 to 500 branch is subdivided into 1 to 250 and 251 to 500. like this oracle divides all the entered data. The actual value contained components are called leaves.
You can get more details at bellow given links.
http://www.orafaq.com/node/1403
Creating new index can hamper the DML performance so there should be ballance between performance of DML and select statments. Consider creating the index if it will be used by many select queries.
Consider the table columns for index creation which will appear in most of the where clause of select statments.

Does BI 7.0 use bit map join indexes?

I have seen several threads on SDN which show that SAP BI is using bit map indexes with Oracle database. However, it is not clear whether BI utilizes bit map join indexes or just bit map index. Bit map index is on a single table whereas bitmap join index is on a join of two or more tables.
It will make sense for SAP BI to use bit map join indexes with star transformations where a join is done among fact and dimension tables.

> Thanks. Another question, are bit map indexes used both for F and E fact tables or just for F. I am not using real-time cubes (where SAP BI uses B-Tree indexes for F table to avoid dead locks).
Why don't you simply check this in your BI system yourself?
And, yes, of course it uses bitmap indexes for both fact table types.
E-fact tables are the same as F-Facttables except that they contain the compressed/rolled up data.
regards,
Lars

EL Map won't work with numerical index - works with string

If I populate a map with a numeric index, the values won't appear when I refer to it as ${myMap[0]} in JSP. In my servlet I populate myMap by doing a put(0,value).
However, when I do a myMap["index0"] or myMap.index0, it works! I simply change the line that populates the Map to put("index0",value).
Why won't it work with a numerical index? Does it have something to do with JDK 1.5's autoboxing? I cast the 0 to an int in the put( ) method, but that makes no difference.
What could be happening here? Does it work for you?
Thanks.

Whats causing this?
Basically autoboxing puts an Integer object into the Map.
ie: map.put(new Integer(0), "myValue")
EL evaluates 0 as a Long and thus goes looking for a Long as the key in the map.
ie it evaluates: map.get(new Long(0))
As a Long is never equal to an Integer object, it does not find the entry in the map.
Thats it in a nutshell.
JSP page demonstrating this:
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<%@ page import="java.util.*" %>
<h2> Server Info</h2>
Server info = <%= application.getServerInfo() %> <br>
Servlet engine version = <%= application.getMajorVersion() %>.<%= application.getMinorVersion() %><br>
Java version = <%= System.getProperty("java.vm.version") %><br>
<%
Map map = new LinkedHashMap();
map.put("2", "String(2)");
map.put(new Integer(2), "Integer(2)");
map.put(new Long(2), "Long(2)");
map.put(42, "AutoBoxedNumber");
pageContext.setAttribute("myMap", map);
Integer lifeInteger = new Integer(42);
Long lifeLong = new Long(42);
%>
<h3>Looking up map in JSTL - integer vs long </h3>
This page demonstrates how JSTL maps interact with different types used for keys in a map.
Specifically the issue relates to autoboxing by java using map.put(1, "MyValue") and attempting to display it as ${myMap[1]}
The map "myMap" consists of four entries with different keys: A String, an Integer, a Long and an entry put there by AutoBoxing Java 5 feature.
<table border="1">
     <tr><th>Key</th><th>value</th><th>Key Class</th></tr>
     <c:forEach var="entry" items="${myMap}" varStatus="status">
     <tr>
       <td>${entry.key}</td>
       <td>${entry.value}</td>
       <td>${entry.key.class}</td>
     </tr>
     </c:forEach>
</table>
    <h4> Accessing the map</h4>
    Evaluating: ${"${myMap['2']}"} = <c:out value="${myMap['2']}"/><br>
    Evaluating: ${"${myMap[2]}"}   = <c:out value="${myMap[2]}"/><br>
    Evaluating: ${"${myMap[42]}"}   = <c:out value="${myMap[42]}"/><br>
    <p>
    As you can see, the EL Expression for the literal number retrieves the value against the java.lang.Long entry in the map.
    Attempting to access the entry created by autoboxing fails because a Long is never equal to an Integer
    <p>
    lifeInteger = <%= lifeInteger %><br/>
    lifeLong = <%= lifeLong %><br/>
    lifeInteger.equals(lifeLong) : <%= lifeInteger.equals(lifeLong) %> <br>
    That at least explains what is going on.
Not sure exactly what I would do to "fix" it. Would have to look at what the requirements are. But basically I think it would end up as having to use Longs rather than Integers as keys in the map, meaning autoboxing could not be used.
Cheers,
evnafets

How to get 64-bit install and 32-bit client to work on 1 pc

I have installed a full 64-bit 11g R2 install on my Windows 7 D: drive, installed two DB's, worked great. Then I realized application I need to support requires 32-bit client (for drivers) so I installed the 11g client also.
My problem is that my registry only shows one ORACLE_HOME--the 64-bit full install whereas Cognos reqs to point to 32-bit client.
Sqlplus in 64-bit works fine (D:\oracle\app\dock\product\11.2.0\dbhome_1\BIN\sqlplus.exe) whereas the 32-bit client sqlplus (D:\oracle\client\app\dock\product\11.2.0\client_1\BIN\sqlplus.exe) does not work. The error is:
ORA-12560: TNS:protocol adapter error
If I open cmd prompt and navigate to 32-bit sqlplus under client this WILL work to login (but then I noticed it was using the 64-bit ORACLE_HOME and PATH settings if I typed set). In order to fix Cognos, I changed my ORACLE_HOME and path to point to the 32-bit client (i.e. from D:\oracle\app\dock\product\11.2.0\dbhome_1 to
ORACLE_HOME = D:\oracle\client\app\dock\product\11.2.0\client_1
PATH = D:\oracle\client\app\dock\product\11.2.0\client_1\bin;C:\Program Files (x86)\NVIDIA Corporation\PhysX\Common;%SystemRoot%\system32;%SystemRoot%;%SystemRoot%\System32\Wbem;%SYSTEMROOT%\System32\WindowsPowerShell\v1.0\;C:\Program Files\ThinkPad\Bluetooth Software\;C:\Program Files\ThinkPad\Bluetooth Software\syswow64;C:\Program Files\Intel\WiFi\bin\;C:\Program Files\Common Files\Intel\WirelessCommon\
Guess what? This stopped both the 64-bit and 32-bit sqlplus from working, even after bouncing the computer. Now the listener (64-bit) OracleOraDb11g_home1TNSListener will also not start either.
Sooooo, I think I need to set the OH and PATH back to the 64-bit as that is what the Listener requires but any ideas how to get the 32-bit sqlplus to also work?!?
Thanks in advance for any help!

lo**** wrote:
My problem is that my registry only shows one ORACLE_HOME--the 64-bit full install whereas Cognos reqs to point to 32-bit client. The env/reg variables probably do exist/show, only in the right place. In Win 64-bit, there's a separate branch of reg entries for 32-bit (look for WoW6432Node).
>
... whereas the 32-bit client sqlplus (D:\oracle\client\app\dock\product\11.2.0\client_1\BIN\sqlplus.exe) does not work. The error is:
ORA-12560: TNS:protocol adapter errorIt works as expected. Since there is no Oracle instance in the Client home (no surprise), you can't connect "locally" from the 32-bit sqlplus. I.e. you need to use "...@connectident" in the connect string.
In order to fix Cognos, I changed my ORACLE_HOME and path to point to the 32-bit client (i.e. from D:\oracle\app\dock\product\11.2.0\dbhome_1 toOn Windows platform, ORACLE_HOME should not be set by user (it is already set by installer, in the Registry).
To pick up proper settings, PATH need to be set or used.
>
Sooooo, I think I need to set the OH and PATH back to the 64-bit as that is what the Listener requires but any ideas how to get the 32-bit sqlplus to also work?!?Please remove OH from env system settings.
Multiple homes on Windows is often a source of problems, since extra consideration and setup is needed more than just installing the software.
If "Cognos" relies on system PATH, then one way to go might be:
- put path to 32-bit Client bin folder first in PATH
- set up a shortcut to command window with only 64-bit in PATH, for times when you need to administer the database via command line.

How bit map index works?

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