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How and when reindexing a db?

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fabianus76
Posting Yak Master

191 Posts

Posted - 2006-08-16 : 13:14:57

Hello guys,

Two things:

1) Could somebody explain me how to reindex all tables in my db?

2) How do I know when I should reindex my db?

Thank you very much for any help!

Regards,
Fabian

my favorit hoster is ASPnix : www.aspnix.com !

spirit1
Cybernetic Yak Master

11752 Posts

Posted - 2006-08-16 : 13:20:48

1. using DBCC DBREINDEX or DBCC INDEXDEFRAG or drop index create index or alter index statements
2. well run DBCC SHOWCONTIG to see how much fragmentation you have in your indexes. I defragment my indexes when the fragmentation reaches 10-20% based on the table.

some people have a scheduled job that rebuilds the indexes every day in low traffic hours.
SQL server 2005 has also improved greatly on live index rebuild.

Go with the flow & have fun! Else fight the flow

blog thingie: http://weblogs.sqlteam.com/mladenp

fabianus76
Posting Yak Master

191 Posts

Posted - 2006-08-16 : 15:14:12

Thank you very much Spirit1. That's very useful for me.

Could you help me to interpreter the report for one of my tables:

DBCC SHOWCONTIG scanning 'cs_UserProfile' table...
Table: 'cs_UserProfile' (2114822596); index ID: 1, database ID: 18
TABLE level scan performed.
- Pages Scanned................................: 27
- Extents Scanned..............................: 6
- Extent Switches..............................: 19
- Avg. Pages per Extent........................: 4.5
- Scan Density [Best Count:Actual Count].......: 20.00% [4:20]
- Logical Scan Fragmentation ..................: 96.30%
- Extent Scan Fragmentation ...................: 83.33%
- Avg. Bytes Free per Page.....................: 5165.3
- Avg. Page Density (full).....................: 36.18%

The percentage you're talking about, is it the Logical Scan Fragmentation?

Thank you very much for your help!

Regards,
Fabian

my favorit hoster is ASPnix : www.aspnix.com !

tkizer
Almighty SQL Goddess

38200 Posts

Posted - 2006-08-16 : 15:14:59

http://weblogs.sqlteam.com/tarad/archive/2006/04/11/9585.aspx

Tara Kizer

fabianus76
Posting Yak Master

191 Posts

Posted - 2006-08-17 : 08:39:49

Here is a nice way to reindex all tables :

USE DatabaseName --Enter the name of the database you want to reindex

DECLARE @TableName varchar(255)

DECLARE TableCursor CURSOR FOR
SELECT table_name FROM information_schema.tables
WHERE table_type = 'base table'

OPEN TableCursor

FETCH NEXT FROM TableCursor INTO @TableName
WHILE @@FETCH_STATUS = 0
BEGIN
DBCC DBREINDEX(@TableName,' ',90)
FETCH NEXT FROM TableCursor INTO @TableName
END

CLOSE TableCursor

DEALLOCATE TableCursor

I found this here : http://www.sql-server-performance.com/rebuilding_indexes.asp

Regards,
Fabian

my favorit hoster is ASPnix : www.aspnix.com !

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