RE: bitmapped indexes

From: Hately, Mike (NESL-IT) <Mike.Hately_at_npowernorthern.com>
Date: Tue, 14 Jan 2003 05:59:00 -0800
Message-ID: <F001.0052F01D.20030114055900@fatcity.com>

It's from a paper called "Bitmap Indexing in Oracle7.3 and 8.0" which is available at
http://www.newagetraining.com/library/ora_dev/sql_plsql/script/BitmapIndexes .pdf
<http://www.newagetraining.com/library/ora_dev/sql_plsql/script/BitmapIndexe
s.pdf>
The theory is true in relation to data loads rather than OLTP operations.  

This quote from Tech Note 70067.1 outlines a benefit of bitmap indexes :  

• Very efficient parallel DML and loads: Bitmap indexes benefit data warehousing applications but they are not appropriate for OLTP applications with a heavy load of concurrent INSERTs, UPDATEs, and DELETEs. In a data warehousing environment, data is usually maintained by way of bulk inserts and updates. Index maintenance is deferred until the end of each DML operation. For example, if you insert 1000 rows, the inserted rows are placed into a sort buffer and then the updates of all 1000 index entries are batched. (This is why SORT_AREA_SIZE must be set properly for good performance with inserts and updates on bitmap indexes.) Thus, each bitmap segment is updated only once per DML operation, even if more than one row in that segment changes.

Regards,
Mike Hately    

 -----Original Message-----
Sent: 14 January 2003 12:54
To: Multiple recipients of list ORACLE-L

It was filtered by Listguru ... where did you get it from? Maybe we can pick it up at the source ...

Raj

---

Rajendra Jamadagni MIS, ESPN Inc. Rajendra dot Jamadagni at ESPN dot com
Any opinion expressed here is personal and doesn't reflect that of ESPN Inc.

QOTD: Any clod can have facts, but having an opinion is an art!

-----Original Message-----
<mailto:andreyb_at_elrontelesoft.com> ]

Sent: Tuesday, January 14, 2003 5:49 AM To: Multiple recipients of list ORACLE-L

Hi !
I don't remember where I got the paper, but I am attaching it.

Cheers.

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Author: Hately, Mike (NESL-IT)
  INET: Mike.Hately_at_npowernorthern.com

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Received on Tue Jan 14 2003 - 07:59:00 CST