Talk:Bitmap index

message: See Prof. Lemire's comment on the usability of bitmap indices. --Ragib (talk) 15:01, 20 August 2008 (UTC)
thread_title: Usage

message: My point for removing the formula is that it's really irrelevant. What needs to be explained, is that the number of indexes grows very quickly with the number of columns, and this can be explained better in words than with the formula given in the article.
Nobody is going to whip out a calculator and wonder "How many indexes will I need to create in order to satisfy all possible queries to this table?". In practice, the number of different possible queries that make sense is always lower than the theoretical number; for instance, rarely will anyone specify *both* a person's name and email address in a query, because either of these already identifies a person almost uniquely. Even if the user specifies both, an index on either the name or email column will satisfy the query quickly enough because the number of results is so small anyway.
Further, you often have date columns that are exclusively used for range queries -- so they always need to be last in any useful index. Not to mention full text indexes. So the formlua is pretty much useless anyway. -- intgr [talk] 13:47, 13 October 2009 (UTC)
replies: text: While none will create all possible indexes for 20 columns indeed, this formula is still of interest to many users, since they don't know how big the number is after it had "grown very fast". And yes, many will whip out a calculator and count, just to make sure they don't really want to create this many indexes. This is not a guide to the table indexing, this is an encyclopedia article and it is perfectly valid to cover some theoretical concepts here, even if they are not of immediate practical use. Abolen (talk) 16:56, 13 October 2009 (UTC)
thread_title:  Reasons for removing the formula 

message: So while the article describes the structure of the bitmap index with an example, as well as many enhancements/variations of it in other sections, it doesn't describe how they are utilized.  The analogy would be performing a binary search with a tree structure, really exemplifies what the benefits are of the structure.  In other words, there is no example that explains how a database engine might utilize a bitmap index to perform a join.
I tried following this linked reference #2, but the link is broken:
http://www.dwoptimize.com/2007/06/101010-answer-to-life-universe-and.html
207.156.50.129 (talk) 23:09, 2 March 2012 (UTC)
thread_title:  Adding information/examples of how the bitmap is utilized, not just its structure. 

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thread_title:  External links modified 

message: This was added a number of years ago with some odd formatting choices by an editor whose only edit was to add this:
:Bitmap based representation can also be used for representing a data structure which is labeled and directed attributed multigraph, used for queries in graph databases.Efficient graph management based on bitmap indices article shows how bitmap index representation can be used to manage large dataset (billions of data points) and answer queries related to graph efficiently.
I'm leaving it here in case there's a way to integrate this into the article better. —Locke Cole • t • c 16:09, 9 May 2021 (UTC)
thread_title:  Removed content