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Home > Archive > microsoft.public.sqlserver.server > June 2002 > Index seek and Index Scan
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| Author |
Index seek and Index Scan
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| Sanjay 2002-06-24, 6:19 pm |
| Hi,
I need help on understanding the difference between index
seek and index scan.
Thanks for your help.
Sanjay
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| Andrew J. Kelly 2002-06-24, 7:44 pm |
| Index Seek means that the index was able to be used as you would expect and
the value was efficiently found in the database using the normal btrieve
process. An Index Scan means that the index was read either in whole or a
range from top to bottom. A seek usually means there was either one or only
a few rows that matched the WHERE clause and the matching rows in the table
were found using the index as you would expect. If it was scanned then you
either did not have a proper index to match the WHERE clause but there was
enough info to figure it out in an existing index or the WHERE clause had
too many matches so the engine choose to scan the index and find all the
values instead. BooksOnLine has some info I believe under Index xxx
--
Andrew J. Kelly, SQL Server MVP
TargitInteractive
"Sanjay" <dhakhwa@hotmail.com> wrote in message
news:11a6701c21bdd$08176af0$9a
e62ecf@tkmsftngxa02...
> Hi,
>
> I need help on understanding the difference between index
> seek and index scan.
>
> Thanks for your help.
> Sanjay
| |
| Gert-Jan Strik 2002-06-25, 3:25 pm |
| In addition to Andrew's post: there is a difference between an index
scan of the clustered index and an index scan of a non-clustered index.
When you see a clustered index scan, it usually means SQL-Server is
reading the entire table (sort of table scan).
Gert-Jan
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