Bitmap index Btree n
diff bet index bitmap and btree, how his work... ??1 index B-tree has low cardinality values, whereas Bitmap Index offers high cardinality values.
2. other than the way in which they put in place, one of the functional difference is Bitmap indexes can index null values where as BTREE index cannot.
3 updates tree index on keys was relatively inexpensive, where as a Bitmap index more expensive
Tags: Database
Similar Questions
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How the Btree and Bitmap index works?
Osama_mustafa wrote:
If you google it you will find some topics/article talking about this.Refer to this:
Index bitmap:
http://www.DBA-Oracle.com/oracle_tips_bitmapped_indexes.htmBTREE index
http://www.DBA-Oracle.com/t_garmany_easysql_btree_index.htmBetter not to refer to one of these items, they contain too many errors.
If textbooks are not good enough, then the best source of information indexing is Richard Foote's blog.(Or add "Richard Foote" for your research, you do it for the b-tree or bitmap index.
Concerning
Jonathan Lewis -
Foglight for Oracle - Bitmap Index
All,
Is thre a way for me to detect if an index Dickman is used in a database
Also, I would be able to tell if a lock is the result of a bitmap index.
Thank you!
The index bitmap behave with slightly different locks. Because of the line are stored in the bitmap, no probable outcome of row in the effective closure of the WHO index of locking. In the design of applications, you should pay attention when the bitmap indexes are used on tables with updates.
To find the bitmap indexes, you can use something like
SELECT INDEX_TYPE, TABLE_OWNER, TABLE_NAME, INDEX_NAME
OF dba_indexes
WHERE index_type IN ("BITMAP", "BITMAP AXES on the FUNCTION")
/
Conclusion if a lock is being influenced by a bitmap index wouldn't be a combination to find a blocking lock and check if the locked object is a table with a bitmap index.
The f
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Bitmap index frequently updated useful column or not?
I have a table of transaction with the status column.
Table contains millions of records.
Status, column values can be hold, dealt with, consult, error, completed.
Initially table column populate status pending and later value will be updated to processed or see even then will be updated to completed or error.
Is it useful to have the index bitmap on this column we update frequently on the status value
Is it useful to have the index bitmap on this column we update frequently on the status value
No - your is NOT a valid use for a bitmap index case.
There would be little or NO value with only one index of bitmap on the table, if the column has been updated frequently or not.
The power of the bitmap index is stronger when MULTIPLE indexes are used in the same query to identify/filter data.
See my answers in this thread
https://forums.Oracle.com/forums/thread.jspa?MessageID=10217613�
In this thread I provide more details and code examples and execution of plan that show you a more typical use of bitmap indexes and their power.
Try this code example to get a better understanding of the proper use of the case for the bitmap index.
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When the CBO would not use bitmap indexes available?
I have a large data warehouse table in a star schema classic, with an index number of bitmap for the dimension tables. When you run queries that contain parameters for multiple indexes, the CBO will only use generally one or rarely two bitmap index.
It seems to me that if the indexes are valid, statistics, the values of the parameters are present, etc and the CBO uses a bitmap index in an AND condition, he would like to use all those she could.
there all the parameters that affect or bitmap how indexes him CBO will use? I'm looking for some advice on what to look for or research.
Database is 11.2.0.3 base with no patch.
Thanks in advance,
Sean
rp0428 - who has been deliberate because my question is not "how to solve this problem", that's exactly what I pointed out in my post. Just trying to see if there are all the controls to weight the decision-making community organizations in this area.
OK - then let me simply state it.
No - there are NO these parameters. But most of the posters are not really looking for a simple yes/no answer even if of many word of questions like that.
See my response as of March 18, 2012 19:21 in this thread: https://community.oracle.com/message/10219613?
Here I provide a simple table with SIX bitmap index, a query that uses predicates that combine values since the execution plan and the six columns indicating the different INDEX of BITMAP UNIQUE BITMAP, BITMAP or operations and BITMAP CONVERSION to ROWID.
I won't repeat everything here, but this example should show you that Oracle will limit itself the way you suggest.
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DM 3.1 how to create a Bitmap Index?
How to create a bitmap with SQL Developer Data Modeler 3.1 index? In the relational model, the properties of the General table allows to enumerate the indexes of a table and to clarify some of their attributes as such as columns and uniqueness. In addition, the properties of the plain index allows more options to set the properties of the index. Unfortunately, I'm unable to find the right place to specify that an index is an index of bitmap.
However, maker of data tend to support bitmap indexes because the generated DDL statements for a table with bitmap indices, which was initially imported into the data dictionary, have correct index bitmap creation instructions. However, when I compare all B tree index with bitmap index in Data Modeler I can't find an option that specifies the index type as bitmap. So, I would be very happy if someone could tell me how to create bitmap with Data Modeler 3.1 indices.
Best regards
MiikkaHey Miikka,
physical model is the place where you can define the specifications of database objects created in the relational model. So you open the physical model and you can find the node index under the node for the related table - use dialog for index set to the index of the bitmap image.
Philippe
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Hello
I want to create an index of bitmap on one of the columns in a table. I did request and it failed.
I found there is a NORMAL index combined with VEH_PLATFORM column called "IDX$ $_30AA00021. He followed columnsSQL> CREATE BITMAP INDEX TRANS_N_BITMAPIDX_VEH_PLATFORM ON TRANSACTION_NEW(VEH_PLATFORM) LOCAL; Error starting at line 2 in command: CREATE BITMAP INDEX TRANS_N_BITMAPIDX_VEH_PLATFORM ON TRANSACTION_NEW(VEH_PLATFORM) LOCAL Error at Command Line:2 Column:70 Error report: SQL Error: ORA-01408: such column list already indexed 01408. 00000 - "such column list already indexed" *Cause: *Action:
• VEH_PLATFORM
• VEH_MODEL
• MODL_YR_NBR
• VEH_MAKE
• TXN_PROCS_DT
But I was able to create bitmap index on columns VEH_MODEL, MODL_YR_NBR, and VEH_MAKE without any error.
Why does error for the VEH_PLATFORM column?
Kind regards
SamSo the error message was true. You had already indexed this column
INDEX_OWNER INDEX_NAME COLUMN_NAME COLUMN_POSITION ------------------------------ ------------------------------ ------------------------------ --------------- VISUAL TXN_INDX_PLATFORM1 VEH_PLATFORM 1You cannot have two indexes exact same list of columns
BTW, it's a whole lot of indexes on a table.
Concerning
Peter -
HI can someone tell me, how indexing is made when we use the bitmap index
Thans in advanceHello
Very useful.http://www.juliandyke.com/presentations/BitmapIndexInternals.ppt#403, 13, Bitmap and operation
Kind regards
Simma... -
CBO: full instead of bitmap index use, why table scan?
I have a query in which it is clearly benefitial to use the bitmap index, rather oracle goes for the full table scan. Could you please shed some light on this? Because even a hint does not help, I guess that something prevents oracle (11.1.0.7.0) to use it in a sort of range index scan pass.
installation program:
several select statements:create table test_distance ( x_display number, y_display number, x_rough number(5,2) as (trunc(x_display,2)), y_rough number(5,2) as (trunc(y_display,2))); insert into test_distance (x_display,y_display) (select dbms_random.value(-180,180), dbms_random.value(-90,90) from dual connect by level < 200000); create bitmap index test_bm_xrough on test_distance(x_rough); create bitmap index test_bm_yrough on test_distance(y_rough); create or replace function western_bbox_longitude(x binary_double, y binary_double, radius binary_double) return number is begin --simplified return x - 0.0001*radius; end; / exec dbms_stats.gather_table_stats(user,'TEST_DISTANCE',cascade=>true,estimate_percent=>100);--remember x and y values and use them in the subsequent queries. select * from test_distance where rownum = 1; alter session set statistics_level = all; --no bind variable, no function call -> proper plan select * from test_distance where x_rough = 16.14 and y_rough = -35.53; select * from table(dbms_xplan.display_cursor(null,null,'ALLSTATS LAST')); --with bind variable, no function call -> still proper plan select * from test_distance where x_rough = :xin and y_rough = :yin; select * from table(dbms_xplan.display_cursor(null,null,'ALLSTATS LAST')); --using between, bind variable, no function call -> proper plan select * from test_distance where x_rough between :xin-0.01 and :xin and y_rough between :yin-0.01 and :yin; select * from table(dbms_xplan.display_cursor(null,null,'ALLSTATS LAST')); --full table scan, why? select td.*, trunc(western_bbox_longitude(:xin,:yin,:radius),2) from test_distance td where x_rough = trunc( western_bbox_longitude(:xin,:yin,:radius),2); select * from table(dbms_xplan.display_cursor(null,null,'ALLSTATS LAST')); --forcing oracle to use the index results in bitmap index full instead of range scan, why? select /*+ index( td test_bm_xrough) */ td.*, trunc(western_bbox_longitude(:xin,:yin,:radius),2) from test_distance td where x_rough = trunc( western_bbox_longitude(:xin,:yin,:radius),2); select * from table(dbms_xplan.display_cursor(null,null,'ALLSTATS LAST')); --guessing it might be related to the selectivity of the function doesn't change the plan either associate statistics with functions western_bbox_longitude default selectivity 0.001;Ah sorry, I somehow read the wrong line in your initial statement where it between the function has been used.
Yes it is possible that the selectivity of the function plays a role here. More likely may be the order of execution for the undeterministic functions is then different for literals. However, you can try to work around this problem by using a few different approaches.
encapsulate the function inside a double subseelct
select /*+ index( td test_bm_xrough) */ td.*, (select trunc(western_bbox_longitude(:xin,:yin,:radius),2)) from test_distance td where x_rough = (select trunc(western_bbox_longitude(:xin,:yin,:radius),2) from dual);This should allow to cache the result of the function to a certain extent. Otherwise, the result of the function may be recalculated for each row in the test_distance table.
The same can be achieved with a WITH clause
not testedwith wboxlong as (select trunc(western_bbox_longitude(:xin,:yin,:radius),2) xrough from dual) select /*+ index( td test_bm_xrough) */ td.*, x.xrough from test_distance td join wboxlong x on td.x_rough = x.xroughAlso note that your tip worked. Oracle uses the bitmap indexes to access the data. Index indicator indicates to the CBO to use this index if possible, but is not on the path. If you want a different plan, you can try to apply also the path combined with a suspicion as NO_INDEX_FFS (http://download.oracle.com/docs/cd/B19306_01/server.102/b14200/sql_elements006.htm#SQLRF50413).
Published by: Sven w. on January 3, 2011 18:57
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Hello
I use Oracle 10.2.0.3.0 on Solaris 5.10.
I have a range based to 60 partitions partition table. It is a fact table. I load the data for 60 days in this table. I created a partition for each day, and the partition key is the column date. I've created the table with the partition, but does not create the local bitmap index on the partition keys $vdate, because as far as I know oracle makes the local bitmap index unusable before insert you and then to rebuild it after the charge. Is this fair?
So the best strategy is first load the data in the partition, and then create a local on this partition, is bitmap index - this exact?
For example, in the future, some lines get inserted into an existing partition where the local bitmap index is present, then I should still once rebuild the index on that partition, as in the case of insertion Oracle would have it turned off?
In this table, it has a vactivity column that is a foreign key to a dimension. Several queries use this column here where clause. I also want to create an index of bitmap on this column? On this not partitioned key column, the local bitmap index should be created. Is this fair?
Please also suggest as which is faster, a local bitmap index rebuild after making it unusable, or the deletion and recreation it?
Thank you and best regardsIf you insert only a few lines, you don't need to score the unusable bitmap index partition. The insert will not fail.
However, if you perform a bulk insert several lines, it would be desirable mark it unusable and rebuild after insertion.
You can certainly create an index on the column of the FK.
Hemant K Collette
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Hello
I have a table with defined as above and bitmap index partitions.
I am trying to edit bitmap index gives me the following error:
change the index BITMAP INDEX_NAME local unusable;
Error from the 1 in the command line:
change the unusable BITMAP INDEX_NAME local index
Error report:
SQL error: ORA-00940: invalid ALTER command
Is there anyway I can make unusable index bitmap and make it reusable again once my platelets are made.
Any suggestion is welcome.
Thank you
JThe current syntax is
ALTER INDEX indexname UNUSABLE; -- for the whole indexor
ALTER INDEX indexname MODIFY PARTITION partitionname UNUSABLE ; -- for a specific partition -
Which switch to index for the index bitmap in Oracle Standard Edition
Hello
I have to move from Oracle Enterprise edition to standard edition (oracle11g). As standard edition does not support bitmap indexes. But the current database which is an Enterprise edition a bitmap index a column-based date or varchar2 or column in a table. The tables have approximately 60000000 records. I would like to know what index go for bitmap index.
Kind regards
Vaibhav
Published by: Vaibhav on November 7, 2011 05:35The BTree index certainly can and are frequently used when values are not unique (e.g. are duplicated).
uniqueness isn't the issue. The relative number of distinct values (relative to the total number of lines) is important. An advantage of BitMap index BTree indexes, it's that BTree indexes can be composite - made up of multiple columns.
You can read the documentation on the index.
http://download.Oracle.com/docs/CD/E11882_01/server.112/e25789/indexiot.htm#CBBECABB
http://download.Oracle.com/docs/CD/E11882_01/server.112/e25494/indexes.htm#i1007132
Hemant K Collette
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Hello
I'm little surprised when creating index. I have a partition table with 10784102 files in them. one of its columns have distinct values 8558592 in them.
which is equal to 80% of the data in the table. This column cardinality is very high for btree indexes is good for this situation.
In addition, there no null values in the column as well. However, when I create a btree index
and make a simple index select does not scan. While when I create bitmap on this column indexes it scan index. Here is my test scenario
The two queries of different time taken bitmap, return in 8 seconds while the index btree take 2mints.Btree index explain plan for select SESS_SESSESSIONID from REBE01S2_DG0 SELECT * FROM table(dbms_xplan.display); explain plan succeeded. PLAN_TABLE_OUTPUT ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ Plan hash value: 854853906 ---------------------------------------------------------------------------------------------------------------------------------- | Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | Pstart| Pstop | TQ |IN-OUT| PQ Distrib | ---------------------------------------------------------------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | 10M| 287M| 103K (1)| 00:24:07 | | | | | | | 1 | PX COORDINATOR | | | | | | | | | | | | 2 | PX SEND QC (RANDOM)| :TQ10000 | 10M| 287M| 103K (1)| 00:24:07 | | | Q1,00 | P->S | QC (RAND) | | 3 | PX BLOCK ITERATOR | | 10M| 287M| 103K (1)| 00:24:07 | 1 | 15 | Q1,00 | PCWC | | | 4 | TABLE ACCESS FULL| REBE01S2_DG0 | 10M| 287M| 103K (1)| 00:24:07 | 1 | 15 | Q1,00 | PCWP | | ---------------------------------------------------------------------------------------------------------------------------------- 11 rows selected *drop btree and create bitmap* PLAN_TABLE_OUTPUT ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ Plan hash value: 1533847669 ----------------------------------------------------------------------------------------------------------------------------------------------------- | Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | Pstart| Pstop | TQ |IN-OUT| PQ Distrib | ----------------------------------------------------------------------------------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | 10M| 287M| 7170 (1)| 00:01:41 | | | | | | | 1 | PX COORDINATOR | | | | | | | | | | | | 2 | PX SEND QC (RANDOM) | :TQ10000 | 10M| 287M| 7170 (1)| 00:01:41 | | | Q1,00 | P->S | QC (RAND) | | 3 | PX BLOCK ITERATOR | | 10M| 287M| 7170 (1)| 00:01:41 | 1 | 15 | Q1,00 | PCWC | | | 4 | BITMAP CONVERSION TO ROWIDS | | 10M| 287M| 7170 (1)| 00:01:41 | | | Q1,00 | PCWP | | | 5 | BITMAP INDEX FAST FULL SCAN| MINDX_REBE01S2_DG0_0 | | | | | 1 | 15 | Q1,00 | PCWP | | ----------------------------------------------------------------------------------------------------------------------------------------------------- 12 rows selected
Oracle Database 11 g Enterprise Edition Release 11.2.0.3.0 - 64 bit Production
AMT for 64-bit Windows: Version 11.2.0.3.0 - Production
Table and index both partition local. Rangeuser10858330 wrote:
Hi Jonathan when I use strange terms of suspicion is explain. Pleas take a lookThe first plan that you have demonstrated is exactly as planned during the sess_sesssessionid has not been declared as NOT NULL. However, I notice that you have modified the original request.
select /*+ index_FFS(REBE01S2_DG0(SESS_SESSESSIONID)) */ distinct SESS_SESSESSIONID from REBE01S2_DG0When I remove indication FFS it use another column index
MINDX_REBE01S2_DG0_3 please specify thisBut in the previous post in response to Hemant, there no - this suggests that you are mixing up of your experiences.
And you certainly don't expect to guess what is happening with the other indexes when you don't have it yet we gave the definition of the index.Because the column has not been declared NOT NULL, there wasn't any point in trying to the indicator. Instead you might (for the purpose of investigating a point) run your query with the predicate "sess_sessessionid is not null.
Concerning
Jonathan Lewis -
Bitmap Vs domain of index for large tables
I have a DB warehouse which consists of very large tables.
I have two questions:
1 can I use Bitmap or field type index?
2. use a different tablespace for storing the indices? This would improve performance?
Please give me advice to improve the performance of queries for these large tables (more than 300 M record).
Concerning
When to use bitmap indexes
------------------------------
-The column has a low cardinality: little separate value
-Bitmap indexes are particularly useful for complex with ad-hoc queries
long WHERE clauses or applications of aggregation (containing SUM, COUNT, or other
aggregate functions)
-The table contains the number of lines (1,000,000 lines with 10,000 distinct values)
may be acceptable)
-There are frequent, possibly ad hoc queries on the table
-L' environment is focused on the data warehouse (System DSS). Bitmap indexes are
not ideal for due processing (OLTP) environments transactional online
their locking behavior. It is not possible to lock a single bitmap.
The smallest amount of a bitmap that can be locked is a bitmap segment, which
can be a block of data up to half size. Changing the value of a row results in
a bitmap segment becomes locked, blocking to force change on a number of lines.
This is a serious drawback when there are several UPDATE, INSERT or DELETE
statements made by users. It is not a problem when loading data or
updated to the stock in bulk, as in data warehouse systems.
-Bitmap join indexes are a new method of 9.0 by which joins can be avoided in
pre-creation index bitmap on the join criteria.
The BJI is an effective way of space reduction in the volume of selected data.
The data resulting from the join operation and restrictions are
kept permanently in a BJI. The join condition is a join, equi-internal between the
column/columns in primary key of the dimension and the foreign key tables
column or columns in the fact table.
When to use domain indexes
---------------------------------------
https://docs.Oracle.com/CD/E11882_01/AppDev.112/e41502/adfns_indexes.htm#ADFNS00504
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B - Tree and explanation Index Bitmap
Hi gurus
I am trying to absorb the notion of bitmap index and b-tree, but unable to grasp the concept, so far, I have learned the following:
Index B-Tree
Use in the OLTP environment
It is customary for these types of columns where you have more unique value or we can say that high cardinality
It occupies less storage
Using the corresponding model and ranges
By default, Oracle uses tree indexing
Bitmap index
Use in home environment/OLAP data items
It is customary for these types of columns where repeated values exist or we can say that low cardinality, example are male and female
It seems that these points of difference between the two indexes. I really appreciate if someone give me more explanation on these subjects.
Thanks in advance
Concerning
Muzz
I am trying to absorb the concept index bitmap and tree but unable to grasp the concept,
Then the FIRST place to look is the Oracle documentation; specifically the chapter "Index and Index-Organized Tables" chapter of the Concepts doc.
http://docs.Oracle.com/CD/E25054_01/server.1111/e25789/indexiot.htm
3 indices and Index of Tables
This chapter deals with indices, which are schema objects that can speed up access to the lines of the table and organized index of tables, which are tables stored in an index structure.
This chapter contains the following sections:
This chapter has a lot of basic information on ALL the various types of indexes.
so far, I've learned the following:
Where, exactly, 'have you' who? Most of it is wrong, incomplete or distorted.
Index B-Tree
Use in the OLTP environment
Index B-Tree, by default, are used in all environments.
It is customary for these types of columns where you have more unique value or we can say that high cardinality
They can be used for a cardinality. True - a unique column index is most commonly used for high-cardinality columns. But Oracle may also use an index column, simple or composite, when the data being sought is ENTIRELY contained in one or more indexes, low cardinality.
It occupies less storage
Maybe, maybe not. It is based on the column being indexed, the size of the key values and the cardinality of the key values. For your example "Male and female" there will be only THREE index entries: male, female and null. And each entry is simply a list of ranges of ROWID. This index can be orders of magnitude smaller than the equivalent B-Tree index.
Using the corresponding model and ranges
For the most part correct - although the range queries can be used with the bitmap index which is not a common use.
By default, Oracle uses tree indexing
Fix.
Bitmap index
Use in home environment/OLAP data items
Especially correct - DML on tables with the bitmap index can cause severe performance and throughput problems. The distinction is therefore between environments with medium/high DML on a table compared to the weak or nonexistent DML on a table.
So rather than a distinction between environments (OLAP and warehouse) the distinction is no longer between the TABLES (high/medium DML versus LOW/NO DML). There is nothing wrong at all with the help of the index of the bitmap in an OLAP environment - but these indices should be limited to the tables with low, or no, DML.
It is customary for these types of columns where repeated values exist or we can say that low cardinality, example are male and female
Yes and no.
Yes - a bitmap index is not really appropriate, if there is NO repeat value.
No - part II (low cardinality). The attribute MAJOR missing from what you have posted is that bitmap indexes are ALMOST always used in conjunction with others (usually a bitmap) index.
If one, or more, high cardinality bitmap index can be used VERY effectively together to identify a set of rows to a query.
See my multiple responses in this thread
https://community.oracle.com/message/10219613?
One of my answers presents, in detail, just how many attributes can be combined using several bitmap on both high columns index and low cardinality.
In a later response, I provide the actual sample code and display the execution plan indicating how Oracle just that.
SQL> set serveroutput on
SQL> set autotrace on explain
SQL> select rowid from star_fact where
2 (state = 'CA') or (state = 'CO')
3 and (age = 'young') and (marital_status = 'divorced')
4 and (((summer_sport = 'baseball') and (softdrink = 'pepsi'))
5 or ((summer_sport = 'golf') and (beer = 'coors')));Read the full thread.
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