Comments on: Index columns, selectivity and inequality predicates

By: Gail

Gail — Thu, 27 Jan 2011 17:37:23 +0000

IO subsystem and network speed most likely.

By: Harish Modugu

Harish Modugu — Thu, 27 Jan 2011 17:27:48 +0000

Great work. Thank you very much for all the wonderful and informative posts.I have been wondering how would one speed up a range query on datetime when the query does nothing but an index seek and takes more than 10 secs to return over a million rows?

By: Gail

Gail — Tue, 25 Jan 2011 20:38:37 +0000

Statistics are not indexes. Everything I’ve said about the ability for a query to use an index based on column order applies whether or not there are statistics on the columns or not

By: Wilfred van Dijk

Wilfred van Dijk — Tue, 25 Jan 2011 10:29:15 +0000

If I run “sp_createstats ‘indexonly’”, SQL will create statistics for all columns being used in an index. If so, is the location of columns in an index still an issue?

By: Gail

Gail — Fri, 20 Nov 2009 08:33:26 +0000

Wonderful. Love the verse.

By: Greg Laresn

Greg Laresn — Fri, 20 Nov 2009 07:29:14 +0000

Place Equality column first in your indexes,
you better be bold,
or the index will not be fully seek-able,
so I’ve been told.

Now if you know what is good for you,
then you’ll think of this twice,
So you can remember the nursery rhythm,
that offered this advice.

By: Now syndicating Gail Shaw and Kendal Van Dyke | Brent Ozar - SQL Server DBA

Now syndicating Gail Shaw and Kendal Van Dyke | Brent Ozar - SQL Server DBA — Sat, 05 Sep 2009 18:37:40 +0000

[...] Index columns, selectivity and inequality predicates – understanding how the engine picks an index for your query helps you build better indexes and better queries.

By: Degraft

Degraft — Fri, 29 May 2009 14:14:01 +0000

Thanks man. Your articles are really informative. Thanks

By: Gail

Gail — Fri, 06 Feb 2009 08:01:18 +0000

Pleasure. I’m glad you’re enjoying them

By: Ben

Ben — Fri, 06 Feb 2009 02:59:29 +0000

Thanks for these posts on indexing, they are really informative.