Comments on: Do you always need index on WHERE column ?

By: RNT

RNT — Tue, 02 Dec 2008 11:42:58 +0000

Thanks for sharing. R&T SOlutions

By: Sergio

Sergio — Wed, 23 Jul 2008 00:04:28 +0000

That’s why my queries took some time (with & without index)..

I have a tinint column that takes only 1 and 0 values.
There are about 164000+ rows. Almost all have 0 value, just some of the rows have 1 (in general < 10).

To be more specific, the column name is “file_hidden”. If the value is 1, then that row is not shown to public..

SELECT * FROM files WHERE file_hidden = 0

I guess the only solution in this situation is to use two tables with the same structure.. one for “1″ (hidden from public), one for “0″ (visible to public) rows

By: Son Nguyen

Son Nguyen — Thu, 03 Jul 2008 23:02:13 +0000

What are the possible alternatives to this particular example? When skipping index is faster but not the best? Creating a summary table? Or something else? I’d like to learn from the experts.

By: Johhny

Johhny — Fri, 23 May 2008 08:59:23 +0000

Very interesting website. Keep up the outstanding work and thank you…

By: Making ActiveRecord faster by NOT indexing - Blog - ShiftEleven

Making ActiveRecord faster by NOT indexing - Blog - ShiftEleven — Tue, 29 Apr 2008 17:00:15 +0000

[...] Usually one of the first things I read about on how to speed up ActiveRecord is to index my columns to speed up the lookup of items. “Of course!” But could indexing too much be harmful? [...]

By: Brahmantyo » Blog Archive » Sifat atau budaya?

Brahmantyo » Blog Archive » Sifat atau budaya? — Mon, 29 Oct 2007 13:37:06 +0000

[...] 2. Vadim Xaprb,What about checking selectivity of indexes ? http://www.mysqlperformanceblog.com/2007/08/28/do-you-always-need-index-on-where-column/ [...]

By: Log Buffer #60: a Carnival of the Vanities for DBAs · Steve Karam · The Oracle Alchemist

Fri, 31 Aug 2007 16:03:41 +0000

[...] is all about adding indexes on your WHERE clause columns. Think again! The MySQL Performance Blog posts about cases where an index might not be such a hot idea. This applies to Oracle as well of course, where sometimes a b-tree index just won’t cut [...]

By: MySQL Resources « Technikhil Writing

MySQL Resources « Technikhil Writing — Thu, 30 Aug 2007 01:10:24 +0000

[...] is another blog written by MySQL consultants based in Europe. This blog is focussed more on the performance tuning tips for MySQL. Great resource to learn the various settings and variables in MySQL that can be used to [...]

By: peter

peter — Wed, 29 Aug 2007 13:46:03 +0000

Thanks Mark,

Even thought this is post by Vadim not me

The other important thing to remember about selectivity – it is actually selectivity of value what matters. It is well possible to have column with 2 values indexes if one of them is in 99% of values and other is in 1% and have index well used to retrieve the data for that 1%

Too bad MySQL does not have partial indexes though (I mean so only that 1% could really be indexed)

By: Arnold Daniels

Arnold Daniels — Wed, 29 Aug 2007 12:53:32 +0000

There is a sniplet on MySQL forge to find these useless/harmfull indexes. http://forge.mysql.com/snippets/view.php?id=85