Comments on: SQL SERVER – Difference Between Index Scan and Index Seek

By: Mike

Mike — Thu, 09 May 2013 06:53:13 +0000

Good one…

By: SQL SERVER – Weekly Series – Memory Lane – #012 « SQL Server Journey with SQL Authority

Sat, 19 Jan 2013 01:31:07 +0000

[...] Difference Between Index Scan and Index Seek I have explained the concept of Index Scan and Index Seek earlier but I keep on receiving the same question again and again. SQL Server uses search predicates to make a decision right before applying indexes to any given query. Index Scan happens when an index definition can not point close to a single row satisfy search predicates. In this case SQL Server has to scan multiple pages to find a range of rows which satisfy search predicates. In case of Index Seek SQL Server finds single row matching search predicates using index definition. [...]

By: Matt

Matt — Tue, 25 Sep 2012 16:19:21 +0000

The article would be a little more understandable if we could see examples somehow.

By: John

John — Sun, 09 Sep 2012 15:16:43 +0000

Partial Error, in my opinion.

If ‘ [Index1 on Table1 contains two columns : Col1,Col3 ] ‘ – either Table-Field Value (column) has a null value and filtering is not used; then a possible Index Seek is in fact an Index Scan on 2008 and later SQL Servers versions, in my opinion, by Engine Design standards.

By: GopiKrishan Gosu

GopiKrishan Gosu — Sat, 12 May 2012 06:19:26 +0000

Hi Pinal,
Colud you tell me for 6+ sql developer what are all the topics will ask in interviews.

By: Vaibhav

Vaibhav — Fri, 20 Apr 2012 09:26:55 +0000

If possible can u explain the diff between index seek and scan through diagram/picture ?

By: Ram

Ram — Tue, 06 Mar 2012 21:35:37 +0000

Please take this as constructive criticism.
This article needs to be proof-read with a fine-tooth comb for grammatically correct English.
You are too verbose when it comes to insignificant details and those that need elaborate explanation, you seem to just gloss over them. Case in point — “Index Scan happens when index definition can not point close on single row to satisfy search predicates” -

By: Kuldip Bhatt

Kuldip Bhatt — Sun, 25 Dec 2011 14:06:32 +0000

thanks very nice sir

By: 1111ali

1111ali — Tue, 11 Oct 2011 19:09:06 +0000

It is really a usefull information for DBA while reading exec. plan

By: Just

Just — Mon, 19 Sep 2011 13:34:07 +0000

nice a lot!!!

By: Paras Rangraj

Paras Rangraj — Wed, 20 Apr 2011 04:42:43 +0000

Hi,
I have six table in my query and while looking at the execution plan i found that one of my table is showing Index scan without any kind of predicates. Please let me know whether this query is good or should i optimise this query.

By: Azhar Iqbal

Azhar Iqbal — Fri, 21 Jan 2011 10:00:19 +0000

Hi,
Your articles differs in difficulty levels. As You have readers from all levels of intelligence.
So please carry on these types of articles b/c these are very helpful for normal readers.
Thanks
Azhar

By: Girish Rokade

Girish Rokade — Thu, 30 Dec 2010 08:30:20 +0000

Hi,
Can you tell that which data structures actually columns uses to store the data which has some indexes applied?

By: abhishek

abhishek — Mon, 22 Nov 2010 13:35:19 +0000

Hi Pinal,
I have a simple question, Does the columns used in SELECT clause affect the index usage? e.g. in the scenario (given in article) if we write follwing queries:
SELECT col4, col5 FROM table1 where col1 = ‘abc’ and col3 = ‘xyz’

SELECT col1, col3 FROM table1 where col1 = ‘abc’ and col3 = ‘xyz’

SELECT col1, col4 FROM table1 where col1 = ‘abc’ and col3 = ‘xyz’

As indexes are on col1 and col3, how these queries will behave in terms of index utilization??

By: latha

latha — Thu, 28 Oct 2010 09:17:38 +0000

hai

to improve the performance i partition my table based on a column.but when updating it gives an error

By: shrikrishna

shrikrishna — Wed, 15 Sep 2010 15:17:48 +0000

Hi Ashish

According my knowlegde Sequence is index seek,index scan,table seek and table scan.

By: N R

N R — Tue, 27 Jul 2010 11:18:48 +0000

how to separate date and time

By: Brian Savoie

Brian Savoie — Thu, 24 Dec 2009 21:42:41 +0000

Whether we like this kind of article or not is irrelevant. Anyone who wants to write efficient queries better understand it; which is why I’m trying to! This is the least enjoyable part of writing queries, but the most rewarding and necessary.

I Appreciate this resource, thank you!!

By: Gaurav Pratap

Gaurav Pratap — Mon, 09 Nov 2009 08:23:18 +0000

Agree with all, this give us an insight of functionoing of SQL server.

More such work appreciated.

By: Wayne E. Pfeffer

Wayne E. Pfeffer — Mon, 19 Oct 2009 19:21:47 +0000

I too am interested in more articles like this, especially about indexes.

By: Sonal

Sonal — Tue, 25 Aug 2009 09:40:02 +0000

This article is really useful , and example is very nice to understand. I am looking for this type of example.
Can u provide this type of article regrading INDEX rebuild and reorganize.Thanks a lot.

By: Suresh Kurapati

Suresh Kurapati — Thu, 02 Jul 2009 15:31:50 +0000

Pinal

Thanks for short , simple yet effective information on index scans and seeks. Of course, I (and I am sure all others readers also) will truly appreciate if you can expand more on this subject

By: purushotam Bhardwaj

purushotam Bhardwaj — Sat, 20 Jun 2009 07:34:31 +0000

I want more example for index scan and index seek

By: Abhilash

Abhilash — Thu, 18 Jun 2009 10:01:22 +0000

As you guessed I’s looking for this kind of articles.
Thanks.

By: Jose Mariano Alvarez

Jose Mariano Alvarez — Tue, 24 Feb 2009 03:19:46 +0000

Interesting article. I prefer to say (when related to predicates), that “Indexseek” is used by engine when a very low percentage of rows of table satisfy the predicate.