Return of Index Analysis Part 1

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Time for part two of my continued Index Analysis query.  The previous posts in this series are:

  1. Analyze Your Indexes Part 1 – Combine existing index statistics and missing indexes into a single output
  2. Analyze Your Indexes Part 2 – Find existing duplicate and overlapping indexes
  3. Analyze Your Indexes Part 3 – Find the relationship between indexes and foreign keys
  4. Analyze Your Indexes Part 4 – Add size and current memory utilization
  5. Analyze Your Indexes Part 5 – Add in index analysis guidelines
  6. Analyze Your Indexes Part 6 – Add in blocking statistics
  7. Analyzing Your Indexes with a Custom Report

I’ve linked to these posts enough lately that we are heading into the meat of it all.  So let’s start adding in some new data and talking about what we have now.

This is the seventh part, or the first in the next, series on an index analysis script that I often use.  The previous posts in this series are:

  1. Analyze Your Indexes Part 1 – Combine existing index statistics and missing indexes into a single output
  2. Analyze Your Indexes Part 2 – Find existing duplicate and overlapping indexes
  3. Analyze Your Indexes Part 3 – Find the relationship between indexes and foreign keys
  4. Analyze Your Indexes Part 4 – Add size and current memory utilization
  5. Analyze Your Indexes Part 5 – Add in index analysis guidelines
  6. Analyze Your Indexes Part 6 – Add in blocking statistics
  7. Analyzing Your Indexes with a Custom Report

I’ve linked to these posts enough lately that we are heading into the meat of it all.  So let’s start adding in some new data and talking about what we have now.

Information from Sys.dm_db_index_operational_stats

Based on some of the work done in recent posts on the DMV sys.dm_db_index_operational_stats we’ll be adding some information from this DMV to the index analysis query.

Specifically, the information from the following columns will be added:

  • range_scan_count (bigint) – Cumulative count of range and table scans started on the index or heap.
  • singleton_lookup_count (bigint) – Cumulative count of single row retrievals from the index or heap.
  • leaf_insert_count (bigint) – Cumulative count of leaf-level inserts.
  • leaf_delete_count (bigint) – Cumulative count of leaf-level deletes.
  • leaf_update_count (bigint) – Cumulative count of leaf-level updates.
  • leaf_ghost_count (bigint) – Cumulative count of leaf-level rows that are marked as deleted, but not yet removed. These rows are removed by a cleanup thread at set intervals.
  • leaf_page_merge_count (bigint) – Cumulative count of page merges at the leaf level.
  • nonleaf_insert_count (bigint) – Cumulative count of inserts above the leaf level.
  • nonleaf_delete_count (bigint) – Cumulative count of deletes above the leaf level.
  • nonleaf_update_count (bigint) – Cumulative count of updates above the leaf level.
  • nonleaf_page_merge_count (bigint) – Cumulative count of page merges above the leaf level.
  • leaf_allocation_count (bigint) – Cumulative count of leaf-level page allocations in the index or heap.  For an index, a page allocation corresponds to a page split.
  • nonleaf_allocation_count (bigint) – Cumulative count of page allocations caused by page splits above the leaf level.
  • page_latch_wait_count (bigint) – Cumulative number of times the Database Engine waited, because of latch contention.
  • page_latch_wait_in_ms (bigint) – Cumulative number of milliseconds the Database Engine waited, because of latch contention.
  • page_io_latch_wait_count (bigint) – Cumulative number of times the Database Engine waited on an I/O page latch.
  • page_io_latch_wait_in_ms (bigint) – Cumulative number of milliseconds the Database Engine waited on a page I/O latch.
  • tree_page_latch_wait_count (bigint) – Subset of page_latch_wait_count that includes only the upper-level B-tree pages. Always 0 for a heap.
  • tree_page_latch_wait_in_ms (bigint) – Subset of page_latch_wait_in_ms that includes only the upper-level B-tree pages. Always 0 for a heap.
  • tree_page_io_latch_wait_count (bigint) – Subset of page_io_latch_wait_count that includes only the upper-level B-tree pages. Always 0 for a heap.
  • tree_page_io_latch_wait_in_ms (bigint) – Subset of page_io_latch_wait_in_ms that includes only the upper-level B-tree pages. Always 0 for a heap.

Some Stuff from Sys.dm_db_index_usage_stats

And it was probably an former oversight on my part, but there was a column that should have been added previously from sys.dm_db_index_usage_stats that will added as well.

  • user_updates (bigint) - Number of updates by user queries.

More from Sys.Indexes

That leaves us with a couple more columns to add.  Now there isn’t really a good reason, but the last version of this query didn’t include information on the fill factor for indexes.

  • fill_factor (tinyint) – Percentage of free space left on pages the index was created or rebuilt.
  • is_padded (bit) - Boolean value indicating whether fill factor is applied to nonleaf levels

Index Analysis Query

Adding those columns into the previous query get us up to the current version:


SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED

DECLARE @ObjectID int
,@DB_ID int

SELECT @ObjectID = OBJECT_ID('')
,@DB_ID = db_id()

IF OBJECT_ID('tempdb..#IndexBaseLine') IS NOT NULL
DROP TABLE #IndexBaseLine

CREATE TABLE #IndexBaseLine
(
row_id int IDENTITY(1,1)
,index_action varchar(10)
,schema_id int
,schema_name sysname
,object_id int
,table_name sysname
,index_id int
,index_name nvarchar(128)
,is_unique bit DEFAULT(0)
,has_unique bit DEFAULT(0)
,type_desc nvarchar(67)
,partition_number int
,fill_factor tinyint
,is_padded bit
,reserved_page_count bigint
,size_in_mb decimal(12, 2)
,buffered_page_count int
,buffer_mb decimal(12, 2)
,pct_in_buffer decimal(12, 2)
,table_buffer_mb decimal(12, 2)
,row_count bigint
,impact int
,existing_ranking bigint
,user_total bigint
,user_total_pct decimal(6, 2)
,estimated_user_total_pct decimal(6, 2)
,user_seeks bigint
,user_scans bigint
,user_lookups bigint
,user_updates bigint
,read_to_update_ratio nvarchar(30)
,read_to_update int
,update_to_read int
,row_lock_count bigint
,row_lock_wait_count bigint
,row_lock_wait_in_ms bigint
,row_block_pct decimal(6, 2)
,avg_row_lock_waits_ms bigint
,page_latch_wait_count bigint
,avg_page_latch_wait_ms bigint
,page_io_latch_wait_count bigint
,avg_page_io_latch_wait_ms bigint
,tree_page_latch_wait_count bigint
,avg_tree_page_latch_wait_ms bigint
,tree_page_io_latch_wait_count bigint
,avg_tree_page_io_latch_wait_ms bigint
,read_operations bigint
,leaf_writes bigint
,leaf_page_allocations bigint
,leaf_page_merges bigint
,nonleaf_writes bigint
,nonleaf_page_allocations bigint
,nonleaf_page_merges bigint
,indexed_columns nvarchar(max)
,included_columns nvarchar(max)
,indexed_columns_compare nvarchar(max)
,included_columns_compare nvarchar(max)
,duplicate_indexes nvarchar(max)
,overlapping_indexes nvarchar(max)
,related_foreign_keys nvarchar(max)
,related_foreign_keys_xml xml
)

IF OBJECT_ID('tempdb..#ForeignKeys') IS NOT NULL
DROP TABLE #ForeignKeys

CREATE TABLE #ForeignKeys
(
foreign_key_name sysname
,object_id int
,fk_columns nvarchar(max)
,fk_columns_compare nvarchar(max)
)

;WITH AllocationUnits
AS (
SELECT p.object_id
,p.index_id
,p.partition_number
,au.allocation_unit_id
FROM sys.allocation_units AS au
INNER JOIN sys.partitions AS p ON au.container_id = p.hobt_id AND (au.type = 1 OR au.type = 3)
UNION ALL
SELECT p.object_id
,p.index_id
,p.partition_number
,au.allocation_unit_id
FROM sys.allocation_units AS au
INNER JOIN sys.partitions AS p ON au.container_id = p.partition_id AND au.type = 2
),MemoryBuffer
AS (
SELECT au.object_id
,au.index_id
,au.partition_number
,COUNT(*)AS buffered_page_count
,CONVERT(decimal(12,2), CAST(COUNT(*) as bigint)*CAST(8 as float)/1024) as buffer_mb
FROM sys.dm_os_buffer_descriptors AS bd
INNER JOIN AllocationUnits au ON bd.allocation_unit_id = au.allocation_unit_id
WHERE bd.database_id = db_id()
GROUP BY au.object_id, au.index_id, au.partition_number
)
INSERT INTO #IndexBaseLine
(
schema_id, schema_name, object_id, table_name, index_id, index_name, is_unique, type_desc, partition_number, fill_factor, is_padded
, reserved_page_count, size_in_mb, buffered_page_count, buffer_mb, pct_in_buffer, row_count, existing_ranking, user_total
, user_total_pct, user_seeks, user_scans, user_lookups, user_updates, read_to_update_ratio, read_to_update, update_to_read, row_lock_count
, row_lock_wait_count, row_lock_wait_in_ms, row_block_pct, avg_row_lock_waits_ms, page_latch_wait_count, avg_page_latch_wait_ms
, page_io_latch_wait_count, avg_page_io_latch_wait_ms, tree_page_latch_wait_count, avg_tree_page_latch_wait_ms, tree_page_io_latch_wait_count
, avg_tree_page_io_latch_wait_ms, read_operations, leaf_writes, leaf_page_allocations, leaf_page_merges, nonleaf_writes
, nonleaf_page_allocations, nonleaf_page_merges, indexed_columns, included_columns, indexed_columns_compare, included_columns_compare
)
SELECT
schema_id = s.schema_id
, schema_name = s.name
, object_id = t.object_id
, table_name = t.name
, index_id = i.index_id
, index_name = COALESCE(i.name, 'N/A')
, is_unique = i.is_unique
, type_desc = CASE WHEN i.is_unique = 1 THEN 'UNIQUE ' ELSE '' END + i.type_desc
, partition_number = ps.partition_number
, fill_factor = i.fill_factor
, is_padded = i.is_padded
, reserved_page_count = ps.reserved_page_count
, size_in_mb = CAST(reserved_page_count * CAST(8 as float) / 1024 as decimal(12,2))
, buffered_page_count = mb.buffered_page_count
, buffer_mb = mb.buffer_mb
, pct_in_buffer = CAST(100*buffer_mb/NULLIF(CAST(reserved_page_count * CAST(8 as float) / 1024 as decimal(12,2)),0) AS decimal(12,2))
, row_count = row_count
, existing_ranking = ROW_NUMBER()
OVER (PARTITION BY i.object_id ORDER BY i.is_primary_key desc, ius.user_seeks + ius.user_scans + ius.user_lookups desc)
, user_total = ius.user_seeks + ius.user_scans + ius.user_lookups
, user_total_pct = COALESCE(CAST(100 * (ius.user_seeks + ius.user_scans + ius.user_lookups)
/(NULLIF(SUM(ius.user_seeks + ius.user_scans + ius.user_lookups)
OVER(PARTITION BY i.object_id), 0) * 1.) as decimal(6,2)),0)
, user_seeks = ius.user_seeks
, user_scans = ius.user_scans
, user_lookups = ius.user_lookups
, user_updates = ius.user_updates
, read_to_update_ratio = (1.*(ius.user_seeks + ius.user_scans + ius.user_lookups))/NULLIF(ius.user_updates,0)
, read_to_update = CASE WHEN ius.user_seeks + ius.user_scans + ius.user_lookups >= ius.user_updates
THEN CEILING(1.*(ius.user_seeks + ius.user_scans + ius.user_lookups)/COALESCE(NULLIF(ius.user_updates,0),1))
ELSE 0 END
, update_to_read = CASE WHEN ius.user_seeks + ius.user_scans + ius.user_lookups <= ius.user_updates
THEN CEILING(1.*(ius.user_updates)/COALESCE(NULLIF(ius.user_seeks + ius.user_scans + ius.user_lookups,0),1))
ELSE 0 END
, row_lock_count = ios.row_lock_count
, row_lock_wait_count = ios.row_lock_wait_count
, row_lock_wait_in_ms = ios.row_lock_wait_in_ms
, row_block_pct = CAST(100.0 * ios.row_lock_wait_count/NULLIF(ios.row_lock_count, 0) AS decimal(12,2))
, avg_row_lock_waits_ms = CAST(1. * ios.row_lock_wait_in_ms /NULLIF(ios.row_lock_wait_count, 0) AS decimal(12,2))
, page_latch_wait_count = ios.page_latch_wait_count
, avg_page_latch_wait_ms = CAST(1. * page_latch_wait_in_ms / NULLIF(ios.page_io_latch_wait_count,0) AS decimal(12,2))
, page_io_latch_wait_count = ios.page_io_latch_wait_count
, avg_page_io_latch_wait_ms = CAST(1. * ios.page_io_latch_wait_in_ms / NULLIF(ios.page_io_latch_wait_count,0) AS decimal(12,2))
, tree_page_latch_wait_count = ios.tree_page_latch_wait_count
, avg_tree_page_latch_wait_ms = CAST(1. * tree_page_latch_wait_in_ms / NULLIF(ios.tree_page_io_latch_wait_count,0) AS decimal(12,2))
, tree_page_io_latch_wait_count = ios.tree_page_io_latch_wait_count
, avg_tree_page_io_latch_wait_ms = CAST(1. * ios.tree_page_io_latch_wait_in_ms / NULLIF(ios.tree_page_io_latch_wait_count,0) AS decimal(12,2))
, read_operations = range_scan_count + singleton_lookup_count
, leaf_writes = ios.leaf_insert_count + ios.leaf_update_count + ios.leaf_delete_count + ios.leaf_ghost_count
, leaf_page_allocations = leaf_allocation_count
, leaf_page_merges = ios.leaf_page_merge_count
, nonleaf_writes = ios.nonleaf_insert_count + ios.nonleaf_update_count + ios.nonleaf_delete_count
, nonleaf_page_allocations = ios.nonleaf_allocation_count
, nonleaf_page_merges = ios.nonleaf_page_merge_count
, indexed_columns = STUFF((
SELECT ', ' + QUOTENAME(c.name)
FROM sys.index_columns ic
INNER JOIN sys.columns c ON ic.object_id = c.object_id AND ic.column_id = c.column_id
WHERE i.object_id = ic.object_id
AND i.index_id = ic.index_id
AND is_included_column = 0
ORDER BY key_ordinal ASC
FOR XML PATH('')), 1, 2, '')
, included_columns = STUFF((
SELECT ', ' + QUOTENAME(c.name)
FROM sys.index_columns ic
INNER JOIN sys.columns c ON ic.object_id = c.object_id AND ic.column_id = c.column_id
WHERE i.object_id = ic.object_id
AND i.index_id = ic.index_id
AND is_included_column = 1
ORDER BY key_ordinal ASC
FOR XML PATH('')), 1, 2, '')
, indexed_columns_compare = (SELECT QUOTENAME(ic.column_id,'(')
FROM sys.index_columns ic
WHERE i.object_id = ic.object_id
AND i.index_id = ic.index_id
AND is_included_column = 0
ORDER BY key_ordinal ASC
FOR XML PATH(''))
, included_columns_compare = COALESCE((
SELECT QUOTENAME(ic.column_id, '(')
FROM sys.index_columns ic
WHERE i.object_id = ic.object_id
AND i.index_id = ic.index_id
AND is_included_column = 1
ORDER BY key_ordinal ASC
FOR XML PATH('')), SPACE(0))
FROM sys.tables t
INNER JOIN sys.schemas s ON t.schema_id = s.schema_id
INNER JOIN sys.indexes i ON t.object_id = i.object_id
INNER JOIN sys.dm_db_partition_stats ps ON i.object_id = ps.object_id AND i.index_id = ps.index_id
LEFT OUTER JOIN sys.dm_db_index_usage_stats ius ON i.object_id = ius.object_id AND i.index_id = ius.index_id AND ius.database_id = db_id()
LEFT OUTER JOIN sys.dm_db_index_operational_stats(@DB_ID, NULL, NULL, NULL) ios ON ps.object_id = ios.object_id AND ps.index_id = ios.index_id AND ps.partition_number = ios.partition_number
LEFT OUTER JOIN MemoryBuffer mb ON ps.object_id = mb.object_id AND ps.index_id = mb.index_id AND ps.partition_number = mb.partition_number
WHERE t.object_id = @ObjectID OR @ObjectID IS NULL

INSERT INTO #IndexBaseLine
(schema_id, schema_name, object_id, table_name, index_name, type_desc, impact, existing_ranking, user_total, user_seeks, user_scans, user_lookups, indexed_columns, included_columns)
SELECT s.schema_id
,s.name AS schema_name
,t.object_id
,t.name AS table_name
,'--MISSING--' AS index_name
,'--NONCLUSTERED--' AS type_desc
,(migs.user_seeks + migs.user_scans) * migs.avg_user_impact as impact
,0 AS existing_ranking
,migs.user_seeks + migs.user_scans as user_total
,migs.user_seeks
,migs.user_scans
,0 as user_lookups
,COALESCE(equality_columns + ', ', SPACE(0)) + COALESCE(inequality_columns, SPACE(0)) as indexed_columns
,included_columns
FROM sys.tables t
INNER JOIN sys.schemas s ON t.schema_id = s.schema_id
INNER JOIN sys.dm_db_missing_index_details mid ON t.object_id = mid.object_id
INNER JOIN sys.dm_db_missing_index_groups mig ON mid.index_handle = mig.index_handle
INNER JOIN sys.dm_db_missing_index_group_stats migs ON mig.index_group_handle = migs.group_handle
WHERE mid.database_id = db_id()
AND (mid.object_id = @ObjectID OR @ObjectID IS NULL)

INSERT INTO #ForeignKeys
(foreign_key_name, object_id, fk_columns, fk_columns_compare)
SELECT fk.name + '|PARENT' AS foreign_key_name
,fkc.parent_object_id AS object_id
,STUFF((SELECT ', ' + QUOTENAME(c.name)
FROM sys.foreign_key_columns ifkc
INNER JOIN sys.columns c ON ifkc.parent_object_id = c.object_id AND ifkc.parent_column_id = c.column_id
WHERE fk.object_id = ifkc.constraint_object_id
ORDER BY ifkc.constraint_column_id
FOR XML PATH('')), 1, 2, '') AS fk_columns
,(SELECT QUOTENAME(ifkc.parent_column_id,'(')
FROM sys.foreign_key_columns ifkc
WHERE fk.object_id = ifkc.constraint_object_id
ORDER BY ifkc.constraint_column_id
FOR XML PATH('')) AS fk_columns_compare
FROM sys.foreign_keys fk
INNER JOIN sys.foreign_key_columns fkc ON fk.object_id = fkc.constraint_object_id
WHERE fkc.constraint_column_id = 1
AND (fkc.parent_object_id = @ObjectID OR @ObjectID IS NULL)
UNION ALL
SELECT fk.name + '|REFERENCED' as foreign_key_name
,fkc.referenced_object_id AS object_id
,STUFF((SELECT ', ' + QUOTENAME(c.name)
FROM sys.foreign_key_columns ifkc
INNER JOIN sys.columns c ON ifkc.referenced_object_id = c.object_id AND ifkc.referenced_column_id = c.column_id
WHERE fk.object_id = ifkc.constraint_object_id
ORDER BY ifkc.constraint_column_id
FOR XML PATH('')), 1, 2, '') AS fk_columns
,(SELECT QUOTENAME(ifkc.referenced_column_id,'(')
FROM sys.foreign_key_columns ifkc
WHERE fk.object_id = ifkc.constraint_object_id
ORDER BY ifkc.constraint_column_id
FOR XML PATH('')) AS fk_columns_compare
FROM sys.foreign_keys fk
INNER JOIN sys.foreign_key_columns fkc ON fk.object_id = fkc.constraint_object_id
WHERE fkc.constraint_column_id = 1
AND (fkc.referenced_object_id = @ObjectID OR @ObjectID IS NULL)

UPDATE ibl
SET duplicate_indexes = STUFF((SELECT ', ' + index_name AS [data()]
FROM #IndexBaseLine iibl
WHERE ibl.object_id = iibl.object_id
AND ibl.index_id <> iibl.index_id
AND ibl.indexed_columns_compare = iibl.indexed_columns_compare
AND ibl.included_columns_compare = iibl.included_columns_compare
FOR XML PATH('')), 1, 2, '')
,overlapping_indexes = STUFF((SELECT ', ' + index_name AS [data()]
FROM #IndexBaseLine iibl
WHERE ibl.object_id = iibl.object_id
AND ibl.index_id <> iibl.index_id
AND (ibl.indexed_columns_compare LIKE iibl.indexed_columns_compare + '%'
OR iibl.indexed_columns_compare LIKE ibl.indexed_columns_compare + '%')
AND ibl.indexed_columns_compare <> iibl.indexed_columns_compare
FOR XML PATH('')), 1, 2, '')
,related_foreign_keys = STUFF((SELECT ', ' + foreign_key_name AS [data()]
FROM #ForeignKeys ifk
WHERE ifk.object_id = ibl.object_id
AND ibl.indexed_columns_compare LIKE ifk.fk_columns_compare + '%'
FOR XML PATH('')), 1, 2, '')
,related_foreign_keys_xml = CAST((SELECT foreign_key_name
FROM #ForeignKeys ForeignKeys
WHERE ForeignKeys.object_id = ibl.object_id
AND ibl.indexed_columns_compare LIKE ForeignKeys.fk_columns_compare + '%'
FOR XML AUTO) as xml)
FROM #IndexBaseLine ibl

INSERT INTO #IndexBaseLine
(schema_id, schema_name, object_id, table_name, index_name, type_desc, existing_ranking, indexed_columns)
SELECT s.schema_id
,s.name AS schema_name
,t.object_id
,t.name AS table_name
,fk.foreign_key_name AS index_name
,'--MISSING FOREIGN KEY--' as type_desc
,9999
,fk.fk_columns
FROM sys.tables t
INNER JOIN sys.schemas s ON t.schema_id = s.schema_id
INNER JOIN #ForeignKeys fk ON t.object_id = fk.object_id
LEFT OUTER JOIN #IndexBaseLine ia ON fk.object_id = ia.object_id AND ia.indexed_columns_compare LIKE fk.fk_columns_compare + '%'
WHERE ia.index_name IS NULL

;WITH Aggregation
AS (
SELECT row_id
,CAST(100. * (user_seeks + user_scans + user_lookups)
/(NULLIF(SUM(user_seeks + user_scans + user_lookups)
OVER(PARTITION BY schema_name, table_name), 0) * 1.) as decimal(12,2)) AS estimated_user_total_pct
,SUM(buffer_mb) OVER(PARTITION BY schema_name, table_name) as table_buffer_mb
FROM #IndexBaseLine
)
UPDATE ibl
SET estimated_user_total_pct = COALESCE(a.estimated_user_total_pct, 0)
,table_buffer_mb = a.table_buffer_mb
FROM #IndexBaseLine ibl
INNER JOIN Aggregation a ON ibl.row_id = a.row_id

;WITH IndexAction
AS (
SELECT row_id
,CASE WHEN user_lookups > user_seeks AND type_desc IN ('CLUSTERED', 'HEAP', 'UNIQUE CLUSTERED') THEN 'REALIGN'
WHEN type_desc = '--MISSING FOREIGN KEY--' THEN 'CREATE'
WHEN type_desc = 'XML' THEN '---'
WHEN is_unique = 1 THEN '---'
WHEN type_desc = '--NONCLUSTERED--' AND ROW_NUMBER() OVER (PARTITION BY table_name ORDER BY user_total desc) <= 10 AND estimated_user_total_pct > 1 THEN 'CREATE'
WHEN type_desc = '--NONCLUSTERED--' THEN 'BLEND'
WHEN ROW_NUMBER() OVER (PARTITION BY table_name ORDER BY user_total desc, existing_ranking) > 10 THEN 'DROP'
WHEN user_total = 0 THEN 'DROP'
ELSE '---' END AS index_action
FROM #IndexBaseLine
)
UPDATE ibl
SET index_action = ia.index_action
FROM #IndexBaseLine ibl INNER JOIN IndexAction ia
ON ibl.row_id = ia.row_id

UPDATE ibl
SET has_unique = 1
FROM #IndexBaseLine ibl
INNER JOIN (SELECT DISTINCT object_id FROM sys.indexes i WHERE i.is_unique = 1) x ON ibl.object_id = x.object_id

SELECT
index_action
,schema_name + '.' + table_name as object_name
, index_name
, type_desc
, indexed_columns
, included_columns
, is_unique
, has_unique
, partition_number
, fill_factor
, is_padded
, size_in_mb
, buffer_mb
, table_buffer_mb
, pct_in_buffer
, row_count
, user_total_pct
, estimated_user_total_pct
, impact
, user_total
, user_seeks
, user_scans
, user_lookups
, user_updates
, read_to_update_ratio
, read_to_update
, update_to_read
, row_lock_count
, row_lock_wait_count
, row_lock_wait_in_ms
, row_block_pct
, avg_row_lock_waits_ms
, page_latch_wait_count
, avg_page_latch_wait_ms
, page_io_latch_wait_count
, avg_page_io_latch_wait_ms
, tree_page_latch_wait_count
, avg_tree_page_latch_wait_ms
, tree_page_io_latch_wait_count
, avg_tree_page_io_latch_wait_ms
, read_operations
, leaf_writes
, leaf_page_allocations
, leaf_page_merges
, nonleaf_writes
, nonleaf_page_allocations
, nonleaf_page_merges
, duplicate_indexes
, overlapping_indexes
, related_foreign_keys
, related_foreign_keys_xml
FROM #IndexBaseLine
ORDER BY table_buffer_mb DESC, object_id, user_total DESC

NOTE: Populating the table name in the function for the @ObjectID variable is optional.  If the value of @ObjectID is NULL then information on all tables is returned.

Index Analysis Columns

The query populates the following columns:

  • row_id: Row identifier used for populating the table
  • index_action:Analysis recommendation on action to take on the index
    1. CREATE: Recommend adding the index to the table.
    2. DROP: Recommend dropping the index from the table
    3. BLEND: Review the missing index details to see if the missing index details can be added to an existing index.
    4. REALIGN: Bookmark lookups on the index exceed the number of seeks on the table.  Recommend investigating whether to move the clustered index to another index or add included columns to the indexes that are part of the bookmark lookups.
  • schema_id: Schema ID
  • schema_name: Name of the schema.
  • object_id: Object ID
  • table_name: Name of the table name
  • index_id: Index ID
  • index_name: Name of the index.
  • is_unique: Flag indicating whether an index has a unique index.
  • has_unique: Flag indicating whether the table has a unique index.
  • type_desc: Type of index; either clustered or non-clustered.
  • partition_number: Partition number.
  • fill_factor: Percentage of free space left on pages the index was created or rebuilt.
  • is_padded: Boolean value indicating whether fill factor is applied to nonleaf levels
  • reserved_page_count: Total number of pages reserved for the index.
  • size_in_mb: The amount of space in MB the index utilizes on disk.
  • buffered_page_count: Total number of pages in the buffer for the index.
  • buffer_mb: The amount of space in MB in the buffer for the index.
  • pct_in_buffer: The percentage of an index that is current in the SQL Server buffer.
  • table_buffer_mb: The amount of space in MB in the SQL Server buffer that is being utilized by the table.
  • row_count: Number of rows in the index.
  • impact: Calculation of impact of a potential index.  This is based on the seeks and scans that the index could have utilized multiplied by average improvement the index would have provided.  This is included only for missing indexes.
  • existing_ranking: Ranking of the existing indexes ordered by user_total descending across the indexes for the table.
  • user_total: Total number of seek, scan, and lookup operations for the index.
  • user_total_pct: Percentage of total number of seek, scan, and lookup operations for this index compared to all seek, scan, and lookup operations for existing indexes for the table.
  • estimated_user_total_pct: Percentage of total number of seek, scan, and lookup operations for this index compared to all seek, scan, and lookup operations for existing and potential indexes for the table.  This number is naturally skewed because a seek for potential Index A resulted in another operation on an existing index and both of these operations would be counted.
  • user_seeks: Number of seek operations on the index.
  • user_scans: Number of scan operations on the index.
  • user_lookups: Number of lookup operations on the index.
  • user_updates: Number of update operations on the index.
  • read_to_update_ratio: Ratio of user_seeks, user_scans, and user_lookups to user_updates.
  • read_to_update: Division of user_seeks, user_scans, and user_lookups by user_updates.
  • update_to_read: Division of user_updates to user_seeks, user_scans by user_lookups.
  • row_lock_count: Cumulative number of row locks requested.
  • row_lock_wait_count: Cumulative number of times the Database Engine waited on a row lock.
  • row_lock_wait_in_ms: Total number of milliseconds the Database Engine waited on a row lock.
  • row_block_pct: Percentage of row locks that encounter waits on a row lock.
  • avg_row_lock_waits_ms: Average number of milliseconds the Database Engine waited on a row lock.
  • page_latch_wait_count: Cumulative number of times the page latch waits occurred
  • avg_page_latch_wait_ms: Average number of milliseconds the Database Engine waited on a page latch wait.
  • page_io_latch_wait_count: Cumulative number of times the page IO latch waits occurred
  • avg_page_io_latch_wait_ms: Average number of milliseconds the Database Engine waited on a page IO latch wait.
  • tree_page_latch_wait_count: Cumulative number of times the tree page latch waits occurred
  • avg_tree_page_latch_wait_ms: Average number of milliseconds the Database Engine waited on a tree page latch wait.
  • tree_page_io_latch_wait_count: Cumulative number of times the tree page IO latch waits occurred
  • avg_tree_page_io_latch_wait_ms: Average number of milliseconds the Database Engine waited on a tree page IO latch wait.
  • read_operations: Cumulative count of range_scan_count and singleton_lookup_count operations
  • leaf_writes: Cumulative count of leaf_insert_count, leaf_update_count, leaf_delete_count and leaf_ghost_count operations
  • leaf_page_allocations: Cumulative count of leaf-level page allocations in the index or heap.  For an index, a page allocation corresponds to a page split.
  • leaf_page_merges: Cumulative count of page merges at the leaf level.
  • nonleaf_writes: Cumulative count of leaf_insert_count, leaf_update_count and leaf_delete_count operations
  • nonleaf_page_allocations: Cumulative count of page allocations caused by page splits above the leaf level.
  • nonleaf_page_merges: Cumulative count of page merges above the leaf level.
    indexed_columns: Columns that are part of the index, missing index or foreign key.
  • included_columns: Columns that are included in the index or missing index.
  • indexed_columns_compare: Column IDs that are part of the index, missing index or foreign key
  • included_columns_compare: Column IDs that are included in the index or missing index.
  • duplicate_indexes: List of Indexes that exist on the table that are identical to the index on this row.
  • overlapping_indexes: List of Indexes that exist on the table that overlap the index on this row.
  • related_foreign_keys: List of foreign keys that are related to the index either as an exact match or covering index.
  • related_foreign_keys_xml: XML document listing foreign keys that are related to the index either as an exact match or covering index.

Disclaimers

There are a few things to take note of when looking at this information:

  1. The recommendations in the Index Action column are not black and white recommendations.  They are more light grey ideas of what may be appropriate.  Always use your experience with the database in place of a blanket recommendation.
  2. The information in the DMVs is gathered from when the SQL Server service last started or when the database was last created, which ever event is more recent.
  3. The index statistics accumulated in sys.dm_db_index_operational_stats and sys.dm_db_index_usage_stats are reset when the index is rebuilt.
  4. The index statistics for a table that are accumulated in the DMVs sys.dm_db_missing_index_* are reset whenever an index is created on the table.
  5. The index name provided in the name column for indexes that do not exist is not a recommended name for the index.  It’s just an informative placeholder.

Usage Scenarios

I haven’t included any usage scenarios with this post.  If you have a table profile you’d like to see covered, feel free to comment below or reach out to me via e-mail.  Maybe I can make a post out of it and provide some ideas on improving the indexing for your table while explaining how I use the query results in the post.