One of the main functions of a DBA is to maintain database indexes. There have been several tips written about different commands to use for both index rebuilds and index defrags as well as the differences between index maintenance with SQL Server. In addition, other tips have been written about using maintenance plans to maintain indexes on all databases. One of the issues with maintenance plans is that they don't always seem to be as reliable as you would hope and you also sometimes get false feedback on whether the task actually was successful or not. In this tip we look at a simple script that could be used to rebuild all indexes for all databases.
Solution
The one nice thing about maintenance plans is that it works across multiple databases and therefore you can push out one task to handle the same activity across all of your databases. The problem that I have seen with maintenance plans is that sometimes they do not work as expected, therefore here is another approach.
The script below allows you to rebuild indexes for all databases and all tables within a database. This could be further tweaked to handle only indexes that need maintenance as well as doing either index defrags or index rebuilds.
The script uses two cursors one for the databases and another for the tables within the database. In addition, it uses the INFORMATION_SCHEMA.TABLES view to list all of the tables within a database.
Because we need to change from database to database we also need to create dynamic SQL code for the queries. For the DBCC DBREINDEX option we can just pass in the parameters, but for the ALTER INDEX statement we need to build the query dynamically. Here is the script.
DECLARE @Database VARCHAR(255)
DECLARE @Table VARCHAR(255)
DECLARE @cmd NVARCHAR(500)
DECLARE @fillfactor INT
SET @fillfactor = 90
DECLARE DatabaseCursor CURSOR FOR
SELECT name FROM master.dbo.sysdatabases
WHERE name NOT IN ('master','msdb','tempdb','model','distribution')
ORDER BY 1
OPEN DatabaseCursor
FETCH NEXT FROM DatabaseCursor INTO @Database
WHILE @@FETCH_STATUS = 0
BEGIN
SET @cmd = 'DECLARE TableCursor CURSOR FOR SELECT ''['' + table_catalog + ''].['' + table_schema + ''].['' +
table_name + '']'' as tableName FROM [' + @Database + '].INFORMATION_SCHEMA.TABLES
WHERE table_type = ''BASE TABLE'''
-- create table cursor
EXEC (@cmd)
OPEN TableCursor
FETCH NEXT FROM TableCursor INTO @Table
WHILE @@FETCH_STATUS = 0
BEGIN
IF (@@MICROSOFTVERSION / POWER(2, 24) >= 9)
BEGIN
-- SQL 2005 or higher command
SET @cmd = 'ALTER INDEX ALL ON ' + @Table + ' REBUILD WITH (FILLFACTOR = ' + CONVERT(VARCHAR(3),@fillfactor) + ')'
EXEC (@cmd)
END
ELSE
BEGIN
-- SQL 2000 command
DBCC DBREINDEX(@Table,' ',@fillfactor)
END
FETCH NEXT FROM TableCursor INTO @Table
END
CLOSE TableCursor
DEALLOCATE TableCursor
FETCH NEXT FROM DatabaseCursor INTO @Database
END
CLOSE DatabaseCursor
DEALLOCATE DatabaseCursor
The script will work for both SQL 2000 and higher versions. For SQL 2000 it uses DBREINDEX and for SQL Server 2005 and higher it uses ALTER INDEX. Thanks go out to LittlePanthers for providing the code snippet to check the version of SQL Server.
