SQL

Improve SQL Performance by the following measures:

1. Finding Missing Index in SQL 2008

     Method1:

SELECT sys.objects.name
, (avg_total_user_cost * avg_user_impact) * (user_seeks + user_scans) AS Impact
, 'CREATE NONCLUSTERED INDEX ix_IndexName ON ' + sys.objects.name COLLATE DATABASE_DEFAULT + ' ( ' + IsNull(mid.equality_columns, '') + CASE WHEN mid.inequality_columns IS NULL
THEN ''
ELSE CASE WHEN mid.equality_columns IS NULL
THEN ''
ELSE ',' END + mid.inequality_columns END + ' ) ' + CASE WHEN mid.included_columns IS NULL
THEN ''
ELSE 'INCLUDE (' + mid.included_columns + ')' END + ';' AS CreateIndexStatement
, mid.equality_columns
, mid.inequality_columns
, mid.included_columns
FROM sys.dm_db_missing_index_group_stats AS migs
INNER JOIN sys.dm_db_missing_index_groups AS mig ON migs.group_handle = mig.index_group_handle
INNER JOIN sys.dm_db_missing_index_details AS mid ON mig.index_handle = mid.index_handle AND mid.database_id = DB_ID()
INNER JOIN sys.objects WITH (nolock) ON mid.OBJECT_ID = sys.objects.OBJECT_ID
WHERE (migs.group_handle IN
(
SELECT TOP (500) group_handle
FROM sys.dm_db_missing_index_group_stats WITH (nolock)
ORDER BY (avg_total_user_cost * avg_user_impact) * (user_seeks + user_scans) DESC))
AND OBJECTPROPERTY(sys.objects.OBJECT_ID, 'isusertable')=1

    Method2:

SELECT mig.*, statement AS table_name,
column_id, column_name, column_usage
FROM sys.dm_db_missing_index_details AS mid
CROSS APPLY sys.dm_db_missing_index_columns (mid.index_handle)
INNER JOIN sys.dm_db_missing_index_groups AS mig ON mig.index_handle = mid.index_handle
ORDER BY mig.index_group_handle, mig.index_handle, column_id;

2. Finding slow running queries          

SELECT  creation_time 
        ,last_execution_time
        ,total_physical_reads
        ,total_logical_reads 
        ,total_logical_writes
        , execution_count
        , total_worker_time
        , total_elapsed_time
        , total_elapsed_time / execution_count avg_elapsed_time
        ,SUBSTRING(st.text, (qs.statement_start_offset/2) + 1,
         ((CASE statement_end_offset
          WHEN -1 THEN DATALENGTH(st.text)
          ELSE qs.statement_end_offset END
            - qs.statement_start_offset)/2) + 1) AS statement_text
FROM sys.dm_exec_query_stats AS qs
CROSS APPLY sys.dm_exec_sql_text(qs.sql_handle) st
ORDER BY total_elapsed_time / execution_count DESC;

Cheers
Bala