In this post, I am sharing one script to find the size of Indexes in SQL Server.

The first step for performance optimization is to measure the size of tables and indexes which helps you to find out more about fragmentation.

I have already shared a couple of articles on SQL Server Indexes like: find duplicate indexes, unused indexes and fragmentation of indexes.

You can also access these articles after below T-SQL.

SELECT
	OBJECT_SCHEMA_NAME(i.OBJECT_ID) AS SchemaName
	,OBJECT_NAME(i.OBJECT_ID) AS TableName
	,i.name AS IndexName
	,8 * SUM(au.used_pages) AS IndexSizeInKB
FROM sys.indexes AS i
JOIN sys.partitions AS p 
	ON p.OBJECT_ID = i.OBJECT_ID 
		AND p.index_id = i.index_id
JOIN sys.allocation_units AS au 
	ON au.container_id = p.partition_id
GROUP BY 
	i.OBJECT_ID
	,i.index_id
	,i.name
ORDER BY OBJECT_NAME(i.OBJECT_ID),i.index_id

Other related articles:

SQL Server: Find the total row count and size of the Tables

SQL Server: Script to find Redundant and Duplicate Indexes

SQL Server: Script to find usage of Database Indexes

SQL Server: Script to find Index Average Fragmentation in Percentage

As I am preparing important scripts for SQL Server DBA, so here I am also sharing one more vital script for finding the unused indexes of SQL Server Database.

The management and maintenance of database index is a day to day exercise for a Database Administrator. The wrong or unused index can create performance issues for a frequently used table.

At every insert and update, the data of an index are also changing, and it requires some IO operations. Better to find the unused index and delete it.
I also added “DropStatement” column in script for dropping unused Indexes.

SELECT 
	OBJECT_NAME(i.OBJECT_ID) AS ObjectName
	,i.name AS UnusedIndexName	
	,8 * SUM(au.used_pages) AS IndexSizeInKB
	,CASE
		WHEN i.type = 0 THEN 'Heap'  
		WHEN i.type= 1 THEN 'Clustered' 
		WHEN i.type=2 THEN 'Non-Clustered'   
		WHEN i.type=3 THEN 'XML'   
		WHEN i.type=4 THEN 'Spatial'  
		WHEN i.type=5 THEN 'Clustered columnstore index'   
		WHEN i.type=6 THEN 'Nonclustered columnstore index'  
		WHEN i.type=7 THEN 'Nonclustered hash index.'
	END index_type
	,'DROP INDEX ' + i.name + ' ON ' + OBJECT_NAME(i.OBJECT_ID) AS DropStatement
FROM sys.indexes AS i 
LEFT JOIN sys.dm_db_index_usage_stats AS dius 
	ON dius.OBJECT_ID = i.OBJECT_ID 
		AND i.index_id = dius.index_id 
		AND dius.database_id = DB_ID() 
INNER JOIN sys.partitions AS p 
	ON p.OBJECT_ID = i.OBJECT_ID 
		AND p.index_id = i.index_id 
INNER JOIN sys.allocation_units AS au 
	ON au.container_id = p.partition_id 
WHERE OBJECTPROPERTY(i.OBJECT_ID, 'IsIndexable') = 1 
	AND OBJECTPROPERTY(i.OBJECT_ID, 'IsIndexed') = 1 
	AND dius.index_id IS NULL
	OR (dius.user_updates > 0 
		AND dius.user_seeks = 0 
		AND dius.user_scans = 0 
		AND dius.user_lookups = 0)
GROUP BY OBJECT_NAME(i.OBJECT_ID), i.name, i.type 
ORDER BY OBJECT_NAME(i.OBJECT_ID)

Other SQL Server Index related DBA Scripts:

SQL Server: Script to find Redundant and Duplicate Indexes

SQL Server: Script to find Index Average Fragmentation in Percentage

SQL Server: Script to find Missing Indexes

SQL Server: Script to find Index Operational Stats

In this post, I am going to share one T-SQL script to find duplicate and redundant Indexes of the SQL Server.

I have found some of the junior and intermediate Database Developers, who are creating multiple duplicates indexes which are decreasing the overall performance of the database.

Now the job of the Database Administrator is to find and remove duplicate indexes from the database.

I have prepared a small demonstration by creating some of duplicate indexes and provided script to find that duplicate indexes.

First, create a sample table:

CREATE TABLE dbo.tbl_Students
(
	StudID INT IDENTITY(1,1)
	,FirstName VARCHAR(50)
	,LastName VARCHAR(50)
	,DOB DATETIME
	,CONSTRAINT pk_tbl_Students_StudID PRIMARY KEY(StudID)
)
GO

Create duplicate indexes on LastName column:

CREATE NONCLUSTERED INDEX idx_tbl_Students_LastName_FirstName_DOB
ON dbo.tbl_Students (LastName,FirstName,DOB)
GO

CREATE NONCLUSTERED INDEX idx_tbl_Students_LastName_FirstName
ON dbo.tbl_Students (LastName,FirstName)
GO

CREATE NONCLUSTERED INDEX idx_tbl_Students_LastName
ON dbo.tbl_Students (LastName)
GO

Sample SELECT statements:
Below, both SELECT statements are using only one index (idx_tbl_Students_LastName_FirstName_DOB) because LastName column is duplicated in all the indexes.

SELECT *FROM dbo.tbl_Students WHERE LastName ='Patel' AND FirstName = 'Anvesh'
GO
SELECT *FROM dbo.tbl_Students WHERE LastName ='Patel'
GO

Script to find Duplicate Indexes:

SELECT
	s.Name + '.' + t.Name AS TableName	
	,i.name AS IndexName1	
	,DupliIDX.name AS IndexName2
	,c.name AS ColumnNae
FROM sys.tables AS t 
JOIN sys.indexes AS i
	ON t.object_id = i.object_id
JOIN sys.index_columns ic 
	ON ic.object_id = i.object_id 
		AND ic.index_id = i.index_id 
		AND ic.index_column_id = 1  
JOIN sys.columns AS c 
	ON c.object_id = ic.object_id 
		AND c.column_id = ic.column_id      
JOIN sys.schemas AS s 
	ON t.schema_id = s.schema_id
CROSS APPLY
(
	SELECT 
	   ind.index_id
	   ,ind.name
	FROM sys.indexes AS ind 
	JOIN sys.index_columns AS ico 
	   ON ico.object_id = ind.object_id
	   AND ico.index_id = ind.index_id
	   AND ico.index_column_id = 1  
	WHERE ind.object_id = i.object_id 
	   AND ind.index_id > i.index_id
	   AND ico.column_id = ic.column_id
) DupliIDX     
ORDER BY
    s.name,t.name,i.index_id
GO

The Result:

As I am preparing important scripts for PostgreSQL DBA, so here I am also sharing one more important script to find the unused and duplicate index in PostgreSQL.

The management and maintenance of database index is a day to day exercise for a Database Administrator, and unused index can create a performance issues for the whole database system.

At every insert and update, the data of an index are also changing, and it requires some IO operations. Better to find unused index and drop it.

Sometimes, I found that duplicate indexes on the same table, e.g. same table, same columns, same order of columns and created with a different name. Internally this will also impact to our database performance.

I am sharing two different scripts for finding the unused and duplicate index in PostgreSQL.

Script to find the unused indexes in PostgreSQL:

SELECT
	PSUI.indexrelid::regclass AS IndexName
	,PSUI.relid::regclass AS TableName
FROM pg_stat_user_indexes AS PSUI    
JOIN pg_index AS PI 
    ON PSUI.IndexRelid = PI.IndexRelid
WHERE PSUI.idx_scan = 0 
	AND PI.indisunique IS FALSE;

Script to find the duplicate indexes in PostgreSQL:

SELECT
    indrelid::regclass AS TableName
    ,array_agg(indexrelid::regclass) AS Indexes
FROM pg_index 
GROUP BY 
    indrelid
    ,indkey 
HAVING COUNT(*) > 1;