Comments on: Is a scan a bad thing?

By: stephanie b

stephanie b — Mon, 20 Feb 2012 16:28:28 +0000

Is a scan a bad thing ?
As always, ‘It depends’.

By: Log Buffer #157: a Carnical of the Vanities for DBAs | Pythian Group Blog

Log Buffer #157: a Carnical of the Vanities for DBAs | Pythian Group Blog — Fri, 07 Aug 2009 16:52:15 +0000

[...] a question from SQL in the Wild—is a scan a bad thing? “Let’s imagine a hypothetical DBA who’s doing some performance tuning. He looks at a [...]

By: Weekly Link Post 104 « Rhonda Tipton’s WebLog

Weekly Link Post 104 « Rhonda Tipton’s WebLog — Mon, 03 Aug 2009 01:24:01 +0000

[...] Good article asking the question Is a scan a bad thing? [...]

By: DMJM

DMJM — Sun, 02 Aug 2009 21:54:39 +0000

Regarding the second query where the UPPER function was superfluous – I switched the collation on some columns where case was significant. My user is not going to assume case-insensitivity in her queries and I as database developer am not going to assume the database collation will remain case-insensitive. I would rather trade performance for the possibility of a future subtle error.

By: Gail

Gail — Fri, 31 Jul 2009 21:49:33 +0000

Yeah, I wrote about seeks that do the same amount of work as scans a while back. http://sqlinthewild.co.za/index.php/2009/03/05/when-is-a-seek-actually-a-scan/

The point of this post was just want you said, scans are not always bad, don’t panic and try to get rid of a scan without understanding why it’s there first.

By: SQLDenis

SQLDenis — Fri, 31 Jul 2009 18:38:45 +0000

Gail, sometimes a scan will be exactly the same as a seek. See here for some code, execution plans and statistics IO http://blogs.lessthandot.com/index.php/DataMgmt/DataDesign/is-an-index-scan-always-better-or-faster

I know that it probably doesn’t make a lot of sense but people should not always panic when they see a scan

By: Something for the weekend 31/07/09 | John Sansom - SQL Server DBA in the UK

Something for the weekend 31/07/09 | John Sansom - SQL Server DBA in the UK — Fri, 31 Jul 2009 16:28:17 +0000

[...] Is a scan a bad thing? [...]

By: Donovan

Donovan — Thu, 30 Jul 2009 12:47:01 +0000

Great read does bring insight to a common misconception

By: Gail

Gail — Wed, 29 Jul 2009 13:32:13 +0000

Fixed. Sorry about that.

By: Joe Smith

Joe Smith — Wed, 29 Jul 2009 09:59:39 +0000

The SQL markup got a bit borked in the middle of your article. Any chance of fixing it up because it makes it very hard to read. Otherwise it is a very nice article, and yet another thing for me to keep in mind when trying to clean up my old SQL.