This ultimate script performs compression savings estimation check for an ENTIRE database, includes comparison between PAGE and ROW compression types, cautionary table size checks, AND it generates the remediation scripts for you! (more info: https://eitanblumin.com/2020/02/18/ultimate-compression-savings-estimation-script-entire-database/ )

ultimate_compression_savings_estimation_whole_database.sql

----------------------------------------------------------------
-------- Ultimate Compression Savings Estimation Check ---------
----------------------------------------------------------------
-- Author: Eitan Blumin | https://www.eitanblumin.com
-- Create Date: 2019-12-08
-- Source: http://bit.ly/SQLCompressionEstimation
-- Full Link: https://gist.github.com/EitanBlumin/85cf620f7267b234d677f9c3027fb7ce
-- GitHub Repo: https://github.com/MadeiraData/MadeiraToolbox/blob/master/Utility%20Scripts/ultimate_compression_savings_estimation_whole_database.sql
-- Blog: https://eitanblumin.com/2020/02/18/ultimate-compression-savings-estimation-script-entire-database/
----------------------------------------------------------------
-- Description:
-- ------------
-- This script performs compression savings estimation check for both PAGE and ROW
-- compression for an ENTIRE DATABASE.
-- For each index which passes the check, a corresponding ALTER INDEX command
-- is printed for you to use in order to apply the compression.
-- The script also compares the results of the PAGE and ROW estimations and automatically
-- selects the one with the better savings as the command to print, based on the provided thresholds.
-- This script uses mathematical rounding functions FLOOR and CEILING in a manner which makes it more "cautious".
--
-- Some of the algorithms in this script were adapted from the following resources:
-- https://www.sqlservercentral.com/blogs/introducing-what_to_compress-v2
-- https://github.com/microsoft/tigertoolbox/tree/master/Evaluate-Compression-Gains
-- https://github.com/microsoft/azure-sql-tips
----------------------------------------------------------------
-- Change Log:
-- -----------
-- 2024-06-20 - removed parameter @MinimumScanPctForComparison; removed singleton_lookup_count from calculation.
-- 2021-09-09 - added check for incompatible options SortInTempDB and ResumableBuild being both enabled
-- 2021-09-06 - added @ResumableRebuild parameter
-- 2021-09-01 - some minor bug fixes and code quality fixes
-- 2021-02-02 - added SET NOCOUNT, QUOTED_IDENTIFIER, ARITHABORT, XACT_ABORT ON settings
-- 2021-01-17 - added cautionary parameters to stop/pause execution if CPU utilization is too high 
-- 2021-01-17 - added optional cautionary parameters controlling allowed/forbidden execution window
-- 2021-01-17 - made some changes to threshold parameters based on partition stats (adapted from Azure-SQL-Tips)
-- 2021-01-05 - added informative message about current TempDB available space
-- 2020-12-06 - added @MaximumUpdatePctAsInfrequent and @MinimumScanPctForComparison parameters
-- 2020-12-01 - output remediation script is now idempotent; fixed recommendations in resultset to match actual remediation script
-- 2020-09-30 - added @MaxDOP parameter
-- 2020-09-06 - added support for readable secondaries; added MAXDOP 1 for the query from operational stats to avoid access violation bug
-- 2020-03-30 - added filter to ignore indexes and tables with unsupported LOB/FILESTREAM columns
-- 2020-03-16 - added informational and status messages in output script
-- 2020-03-15 - tweaked default parameter values a bit; added server uptime message
-- 2020-02-26 - added best guess for unknown compression recommendations; improved performance for DBs with many objects
-- 2020-02-19 - added support for Azure SQL DB
-- 2020-02-18 - cleaned the code a bit and fixed some bugs
-- 2020-02-17 - added specific database support; adjusted tabs to match github standard; added compatibility checks
-- 2020-02-16 - added threshold parameters; additional checks based on partition stats and operational stats
-- 2019-12-09 - added ONLINE rebuild option
-- 2019-12-24 - flipped to traditional ratio calculation; added READ UNCOMMITTED isolation level; added minimum difference thresholds for PAGE vs. ROW considerations
----------------------------------------------------------------
-- 
-- IMPORTANT !!!
-- -------------
--
-- 1. Don't forget to change the @DatabaseName parameter value to the one you want to check.
--
-- 2. BE MINDFUL IN PRODUCTION ENVIRONMENTS !
--
--		- If you want to be extra careful, run this script with @FeasibilityCheckOnly set to 1. This will perform only basic checks for compression candidates
--		  based on usage and operational stats only, without running [sp_estimate_data_compression_savings].
--
--		- Running this script with @FeasibilityCheckOnly = 0 may take a very long time on big databases with many tables, and significant IO + CPU stress may be noticeable.
--
--		- Schema-level locks may be held for a while per each table, and will possibly block other sessions performing DDL operations.
--
--		- This script uses [sp_estimate_data_compression_savings] which copies 5 % of your data into TempDB and compresses it there.
--		  If you have very large tables, you must be very careful not to fill out the disk.
--		  Please use the following cautionary threshold parameters to avoid such scenarios: @MaxSizeMBForActualCheck, @TempDBSpaceUsageThresholdPercent
----------------------------------------------------------------
-- Parameters:
-- -----------
DECLARE
	-- Choose what to check:
	 @DatabaseName				SYSNAME		= NULL		-- Specify the name of the database to check. If NULL, will use current.
	,@FeasibilityCheckOnly			BIT		= 1		-- If 1, will only check for potential compression candidates, without using sp_estimate_data_compression_savings and without generating remediation scripts
	,@CheckPerPartition			BIT		= 0		-- If 1, will perform separate estimation checks per partition
	,@MinimumSizeMB				INT		= 256		-- Minimum table/partition size in MB in order to perform estimation checks on it

	-- Cautionary thresholds:
	,@MaxSizeMBForActualCheck		INT		= NULL		-- If a table/partition is bigger than this size (in MB), then sp_estimate_data_compression_savings will NOT be executed for it. If set to NULL, then use available TempDB space instead
	,@TempDBSpaceUsageThresholdPercent	INT		= 60		-- A percentage number between 1 and 100, representing how much of the disk space available to TempDB is allowed to be used for the estimation checks

	-- Cautionary parameters to stop/pause execution if CPU utilization is too high (this affects both the estimation check and the rebuild script):
	,@MaximumCPUPercentForRebuild		INT		= 80		-- Maximum average CPU utilization to allow rebuild. Set to NULL to ignore.
	,@SamplesToCheckAvgForCPUPercent	INT		= 10		-- Number of CPU utilization percent samples to check and average out
	,@MaximumTimeToWaitForCPU		DATETIME	= '00:10:00'	-- Maximum time to continously wait for CPU utilization to drop below threshold, before cancelling execution (HH:MM:SS.MS format). Set to NULL to wait forever.

	-- Optional cautionary parameters controlling allowed execution window (server clock)
	-- You can think of this as your "maintenance window" (24hour based. for example, between 0 and 4):
	,@AllowedRuntimeHourFrom		INT		= NULL		-- If not NULL, will specify minimum hour of day during which rebuilds are allowed
	,@AllowedRuntimeHourTo			INT		= NULL		-- If not NULL, will specify maximum hour of day during which rebuilds are allowed

	-- Optional cautionary parameters controlling forbidden execution window (server clock)
	-- You can think of this as your "business hours" (24hour based. for example, between 6 and 22):
	,@NotAllowedRuntimeHourFrom		INT		= 6		-- If not NULL, will specify minimum time of day during which rebuilds are forbidden
	,@NotAllowedRuntimeHourTo		INT		= 22		-- If not NULL, will specify maximum time of day during which rebuilds are forbidden
	 
	-- Threshold parameters controlling recommendation algorithms based on partition stats:
	,@MinimumCompressibleDataPercent	INT		= 45		-- Minimum percent of compressible in-row data, in order to consider any compression
	,@MaximumUpdatePctAsInfrequent		INT		= 10		-- Maximum percent of updates for all operations to consider as "infrequent updates"
	,@MinimumScanPctForPage			INT		= 40		-- Minimum percent of scans when comparing to update percent, to deem PAGE compression preferable (otherwise, ROW compression will be preferable)
	,@MaximumUpdatePctForPage		INT		= 40		-- Maximum percent of updates when comparing to scan percent, to deem PAGE compression preferable
	,@MaximumUpdatePctForRow		INT		= 60		-- Maximum percent of updates when comparing to scan percent, to deem ROW compression preferable

	-- Threshold parameters controlling recommendation algorithms based on savings estimation check:
	,@CompressionRatioThreshold		FLOAT		= 45		-- Number between 0 and 100 representing the minimum compressed data ratio, relative to current size, for which a check will pass
	,@CompressionSizeSavedMBThreshold	FLOAT		= 200		-- Minimum estimated saved space in MB resulting from compression (affects both PAGE and ROW compressions)
	,@MinimumRatioDifferenceForPage		FLOAT		= 20		-- Minimum difference in percentage between ROW and PAGE compression types, in order to deem PAGE compression preferable
	,@MinimumSavingsMBDifferenceForPage	FLOAT		= 40		-- Minimum difference in saved space in MB between ROW and PAGE compression types, in order to deem PAGE compression preferable

	-- Parameters controlling the structure of output scripts:
	,@OnlineRebuild				BIT		= 1		-- If 1, will generate REBUILD commands with the ONLINE option turned on
	,@ResumableRebuild			BIT		= 0		-- If 1, will generate REBUILD commands with the RESUMABLE option turned on (SQL 2019 and newer only)
	,@SortInTempDB				BIT		= 1		-- If 1, will generate REBUILD commands with the SORT_IN_TEMPDB option turned on. Incompatible with RESUMABLE=ON.
	,@MaxDOP				INT		= NULL		-- If not NULL, will add a MaxDOP option accordingly. Set to 1 to prevent parallelism and reduce workload.

--------------------------------------------------------------------
--     		  DO NOT CHANGE ANYTHING BELOW THIS LINE       	  --
--------------------------------------------------------------------

SET NOCOUNT, ARITHABORT, XACT_ABORT ON;
SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED;

-- Variable declaration
DECLARE @CMD NVARCHAR(MAX), @AvailableTempDBSpaceMB INT, @ErrMsg NVARCHAR(MAX)
DECLARE @CurrDB SYSNAME, @Schema SYSNAME, @Table SYSNAME, @ObjectId INT, @IndexId INT, @IndexName SYSNAME, @Partition INT, @CompressionType VARCHAR(4), @EstimationCheckRecommended BIT, @TotalSizeMB INT, @InRowPercent INT, @ScanPercent INT, @UpdatePercent INT
DECLARE @Results AS TABLE ([object_name] SYSNAME NOT NULL, [schema_name] SYSNAME NOT NULL, index_id int NULL, partition_number int NULL, size_w_current_compression_KB float NULL, size_w_requested_compression_KB float NULL, sample_size_current_KB int NULL, sample_size_requested_KB int NULL)
DECLARE @RebuildOptions NVARCHAR(MAX), @ChecksSkipped BIT

-- Compatibility checks
SELECT @ErrMsg = ISNULL(@ErrMsg + ', ', N'Sorry, this SQL Server version is not supported. Missing object(s): ') + objectname
FROM (
SELECT objectname = CONVERT(nvarchar(500), 'sys.tables')
UNION ALL SELECT 'sys.dm_os_volume_stats' WHERE CONVERT(varchar(300),SERVERPROPERTY('Edition')) <> 'SQL Azure'
UNION ALL SELECT 'sys.master_files' WHERE CONVERT(varchar(300),SERVERPROPERTY('Edition')) <> 'SQL Azure'
UNION ALL SELECT 'sys.dm_db_index_operational_stats'
UNION ALL SELECT 'sys.dm_db_partition_stats'
UNION ALL SELECT 'sys.sp_estimate_data_compression_savings'
UNION ALL SELECT 'sys.indexes'
UNION ALL SELECT 'sys.partitions') AS t
WHERE OBJECT_ID(objectname) IS NULL;

IF @ErrMsg IS NOT NULL
BEGIN
	RAISERROR(@ErrMsg,16,1)
	GOTO Quit;
END

-- Init local variables and defaults
SET @RebuildOptions = N''
IF @ResumableRebuild = 1 SET @OnlineRebuild = 1;
IF @OnlineRebuild = 1 SET @RebuildOptions = @RebuildOptions + N', ONLINE = ON'
IF @ResumableRebuild = 1  SET @RebuildOptions = @RebuildOptions + N', RESUMABLE = ON'
IF @SortInTempDB = 1  SET @RebuildOptions = @RebuildOptions + N', SORT_IN_TEMPDB = ON'
IF @MaxDOP IS NOT NULL SET @RebuildOptions = @RebuildOptions + N', MAXDOP = ' + CONVERT(nvarchar(4000), @MaxDOP)
SET @ChecksSkipped = 0;
SET @FeasibilityCheckOnly = ISNULL(@FeasibilityCheckOnly, 1)

-- Check for incompatible options
IF @SortInTempDB = 1 AND @ResumableRebuild = 1
BEGIN
	RAISERROR(N'SORT_IN_TEMPDB and RESUMABLE are incompatible options. Please pick only one of them.',16,1)
	GOTO Quit;
END

-- Validate mandatory percentage parameters
SELECT @ErrMsg = ISNULL(@ErrMsg + CHAR(10), N'Invalid parameter(s): ') + CONVERT(nvarchar(max), N'' + VarName + N' must be a value between 1 and 100')
FROM
(VALUES
	 ('@MinimumCompressibleDataPercent',@MinimumCompressibleDataPercent)
	,('@MinimumScanPctForPage',@MinimumScanPctForPage)
	,('@MaximumUpdatePctForPage',@MaximumUpdatePctForPage)
	,('@MaximumUpdatePctForRow',@MaximumUpdatePctForRow)
	,('@TempDBSpaceUsageThresholdPercent',@TempDBSpaceUsageThresholdPercent)
	,('@CompressionRatioThreshold',@CompressionRatioThreshold)
	,('@MinimumRatioDifferenceForPage',@MinimumRatioDifferenceForPage)
	,('@MaximumUpdatePctAsInfrequent',@MaximumUpdatePctAsInfrequent)
	,('@MaximumCPUPercentForRebuild',ISNULL(@MaximumCPUPercentForRebuild,100))
) AS v(VarName,VarValue)
WHERE VarValue NOT BETWEEN 1 AND 100 OR VarValue IS NULL
OPTION (RECOMPILE);

IF @ErrMsg IS NOT NULL
BEGIN
	RAISERROR(@ErrMsg,16,1);
	GOTO Quit;
END

-- Validate hour-based parameters
SELECT @ErrMsg = ISNULL(@ErrMsg + CHAR(10), N'Invalid parameter(s): ') + CONVERT(nvarchar(max), N'' + VarName + N' must be a value between 0 and 23')
FROM
(VALUES
	 ('@AllowedRuntimeHourFrom',@AllowedRuntimeHourFrom)
	,('@AllowedRuntimeHourTo',@AllowedRuntimeHourTo)
	,('@NotAllowedRuntimeHourFrom',@NotAllowedRuntimeHourFrom)
	,('@NotAllowedRuntimeHourTo',@NotAllowedRuntimeHourTo)
) AS v(VarName,VarValue)
WHERE VarValue NOT BETWEEN 0 AND 23 AND VarValue IS NOT NULL
OPTION (RECOMPILE);

IF @ErrMsg IS NOT NULL
BEGIN
	RAISERROR(@ErrMsg,16,1);
	GOTO Quit;
END

IF @FeasibilityCheckOnly = 0 AND CONVERT(varchar(300),SERVERPROPERTY('Edition')) <> 'SQL Azure'
BEGIN
	-- Check free space remaining for TempDB
	SET @CMD = N'USE tempdb;
SELECT @AvailableTempDBSpaceMB = SUM(ISNULL(available_space_mb,0)) FROM
(
-- Get available space inside data files
SELECT 
  vs.volume_mount_point
, available_space_mb = SUM(ISNULL(f.size - FILEPROPERTY(f.[name], ''SpaceUsed''),0)) / 128 
			+ SUM(CASE
				-- If auto growth is disabled
				WHEN f.max_size = 0 THEN 0
				-- If remaining growth size is smaller than remaining disk space, use remaining growth size till max size
				WHEN f.max_size > 0 AND (f.max_size - f.size) / 128 < (vs.available_bytes / 1024 / 1024) THEN (f.max_size - f.size) / 128
				-- Else, do not count available growth for this file
				ELSE 0
			END)
FROM sys.master_files AS f
CROSS APPLY sys.dm_os_volume_stats (f.database_id, f.file_id)  AS vs
WHERE f.database_id = 2
AND f.type = 0
GROUP BY vs.volume_mount_point

UNION ALL

-- Get available space on disk for auto-growth
SELECT 
  vs.volume_mount_point
, available_space_mb = vs.available_bytes / 1024 / 1024
FROM sys.master_files AS f
CROSS APPLY sys.dm_os_volume_stats (f.database_id, f.file_id)  AS vs
WHERE f.database_id = 2
AND f.type = 0
-- If max size is unlimited, or difference between current size and max size is bigger than available disk space
AND (f.max_size = -1 OR (f.max_size > 0 AND (f.max_size - f.size) / 128 > (vs.available_bytes / 1024 / 1024)))
GROUP BY vs.volume_mount_point, vs.available_bytes
) AS q OPTION (RECOMPILE);'

	EXEC sp_executesql @CMD, N'@AvailableTempDBSpaceMB INT OUTPUT', @AvailableTempDBSpaceMB OUTPUT

	-- Use @TempDBSpaceUsageThresholdPercent as a cautionary multiplier
	SET @AvailableTempDBSpaceMB = @AvailableTempDBSpaceMB * 1.0 * (@TempDBSpaceUsageThresholdPercent / 100.0)

	IF @MaxSizeMBForActualCheck > FLOOR(@AvailableTempDBSpaceMB / 0.05)
	BEGIN
		RAISERROR(N'ALERT: %d percent of available TempDB Disk Space is less than 5 percent of specified @MaxSizeMBForActualCheck (%d). Please adjust @MaxSizeMBForActualCheck and/or @TempDBSpaceUsageThresholdPercent accordingly.', 16, 1, @TempDBSpaceUsageThresholdPercent, @MaxSizeMBForActualCheck);
		GOTO Quit;
	END
	ELSE IF ISNULL(@MaxSizeMBForActualCheck,0) <= 0 -- If @MaxSizeMBForActualCheck was not specified, use available TempDB space instead
		SET @MaxSizeMBForActualCheck = FLOOR(@AvailableTempDBSpaceMB / 0.05);
	
	RAISERROR(N'-- TempDB Free Disk Space: %d MB, max size for check: %d MB',0,1,@AvailableTempDBSpaceMB, @MaxSizeMBForActualCheck) WITH NOWAIT;
END

IF @OnlineRebuild = 1 AND ISNULL(CONVERT(int, SERVERPROPERTY('EngineEdition')),0) NOT IN (3,5,8)
BEGIN
	RAISERROR(N'-- WARNING: @OnlineRebuild is set to 1, but current SQL edition does not support ONLINE rebuilds.', 0, 1);
END

IF @ResumableRebuild = 1 AND CONVERT(int, (@@microsoftversion / 0x1000000) & 0xff) < 15
BEGIN
	RAISERROR(N'-- WARNING: @ResumableRebuild is set to 1, but current SQL version does not support RESUMABLE rebuilds.', 0, 1);
END

DECLARE @ObjectsToCheck AS TABLE
(
	[database_name] SYSNAME NOT NULL,
	[schema_name] SYSNAME NOT NULL,
	[table_id] int NULL,
	[table_name] SYSNAME NULL,
	[index_id] INT NULL,
	[index_name] SYSNAME NULL,
	[partition_number] INT NULL,
	size_MB INT NULL,
	in_row_percent INT NULL,
	range_scans_percent INT NULL,
	updates_percent INT NULL
);

-- The following code, making use of @CurrDB variable, is written in a way which would make
-- it easier to rewrite so that it can check multiple databases
/* start of potential for-each-db */
SET @CurrDB = ISNULL(@DatabaseName, DB_NAME())
PRINT N'------------------------------------------------------------------------------------'
PRINT N'------------- Compression Savings Estimation Check by Eitan Blumin -----------------'
PRINT N'---------------- Source: http://bit.ly/SQLCompressionEstimation --------------------'
PRINT N'------------------------------------------------------------------------------------'
PRINT N'--- for Server: ' + @@SERVERNAME + N' , Database: ' + QUOTENAME(@CurrDB)
PRINT N'------------------------------------------------------------------------------------'

DECLARE @SqlStartTime DATETIME, @UpTimeDays INT, @SqlStartTimeString VARCHAR(25);
SELECT @SqlStartTime = sqlserver_start_time FROM sys.dm_os_sys_info;
SET @UpTimeDays = DATEDIFF(dd, @SqlStartTime, GETDATE())
SET @SqlStartTimeString = CONVERT(varchar(25), @SqlStartTime, 121)

RAISERROR(N'--- SQL Server is operational since %s (~%d days)', 0, 1, @SqlStartTimeString, @UpTimeDays) WITH NOWAIT;

-- Check whether TempDB is located on same disk as specified database
IF @SortInTempDB = 1 AND CONVERT(varchar(300),SERVERPROPERTY('Edition')) <> 'SQL Azure'
BEGIN
	IF EXISTS (
		SELECT fs.volume_mount_point
		FROM sys.master_files AS df
		CROSS APPLY sys.dm_os_volume_stats(df.database_id, df.file_id) AS fs
		WHERE df.type = 0
		AND df.database_id = DB_ID(@CurrDB)

		INTERSECT
					
		SELECT fs.volume_mount_point
		FROM sys.master_files AS df
		CROSS APPLY sys.dm_os_volume_stats(df.database_id, df.file_id) AS fs
		WHERE df.type = 0
		AND df.database_id = 2
		)
	RAISERROR(N'-- WARNING: @SortInTempDB is set to 1, but TempDB is located on the same disk drive as specified database "%s".', 0, 1, @CurrDB);
END

-- Make sure specified database is accessible
IF DB_ID(@CurrDB) IS NULL OR DATABASEPROPERTYEX(@CurrDB, 'Updateability') <> 'READ_WRITE' OR DATABASEPROPERTYEX(@CurrDB, 'Status') <> 'ONLINE'
BEGIN
	IF @FeasibilityCheckOnly = 0 OR DB_ID(@CurrDB) IS NULL OR DATABASEPROPERTYEX(@CurrDB, 'Status') <> 'ONLINE'
	BEGIN
		RAISERROR(N'Database "%s" is not valid for compression estimation check. Please make sure it is accessible and writeable.',16,1,@CurrDB);
		GOTO Quit;
	END
	ELSE
		RAISERROR(N'-- NOTE: Database "%s" is not writeable. You will not be able to rebuild its indexes here until it is writeable.',10,1,@CurrDB);
END

-- Get list of all un-compressed tables/partitions in the specified database
-- Use a temp table in order to improve performance for databases with many tables
SET @CMD = N'USE ' + QUOTENAME(@CurrDB) + N';
IF OBJECT_ID(''tempdb..#objects'') IS NOT NULL DROP TABLE #objects;
CREATE TABLE #objects
(
  [schema_name] SYSNAME
, [object_id] INT
, [table_name] SYSNAME
, [index_id] INT NULL
, [index_name] SYSNAME NULL
, [partition_number] INT NULL
, [size_MB] INT
, [in_row_percent] INT
);

INSERT INTO #objects
SELECT
	  OBJECT_SCHEMA_NAME(t.object_id)
	, t.object_id
	, t.name
	, p.index_id
	, ix.name
	, partition_number = ' + CASE WHEN @CheckPerPartition = 1 THEN N'p.partition_number' ELSE N'NULL' END + N'
	, size_MB = CEILING(SUM(ISNULL(sps.in_row_data_page_count,0) + ISNULL(sps.row_overflow_used_page_count,0) + ISNULL(sps.lob_reserved_page_count,0)) / 128.0)
	, in_row_percent = ISNULL(
				FLOOR(SUM(ISNULL(sps.in_row_data_page_count,0)) * 1.0 
				/ NULLIF(SUM(ISNULL(sps.in_row_data_page_count,0) + ISNULL(sps.row_overflow_used_page_count,0) + ISNULL(sps.lob_reserved_page_count,0)),0)
				* 100.0), 0)
FROM sys.tables AS t WITH(NOLOCK)
INNER JOIN sys.partitions AS p WITH(NOLOCK) ON t.object_id = p.object_id AND p.data_compression = 0
INNER JOIN sys.indexes AS ix WITH(NOLOCK) ON ix.object_id = t.object_id AND ix.index_id = p.index_id
LEFT JOIN sys.dm_db_partition_stats AS sps WITH(NOLOCK) ON sps.partition_id = p.partition_id
WHERE 
-- Ignore system objects
    t.is_ms_shipped = 0
AND t.object_id > 255
AND OBJECT_SCHEMA_NAME(t.object_id) <> ''sys''
-- Ignore indexes or tables with unsupported LOB/FILESTREAM columns
AND NOT EXISTS
(
SELECT NULL
FROM sys.columns AS c
INNER JOIN sys.types AS t 
ON c.system_type_id = t.system_type_id
AND c.user_type_id = t.user_type_id
LEFT JOIN sys.index_columns AS ixc
ON ixc.object_id = c.object_id
AND ixc.column_id = c.column_id
AND ix.index_id = ixc.index_id
WHERE (t.[name] in (''text'', ''ntext'', ''image'') OR c.is_filestream = 1)
AND ix.object_id = c.object_id
AND (ix.index_id IN (0,1) OR ixc.index_id IS NOT NULL)
)
GROUP BY
	  t.object_id
	, t.name
	, p.index_id
	, ix.name' 
	+ CASE WHEN @CheckPerPartition = 1 THEN N', p.partition_number' ELSE '' END
+ CASE WHEN ISNULL(@MinimumSizeMB,0) > 0 THEN N'
HAVING
	CEILING(SUM(ISNULL(sps.in_row_data_page_count,0) + ISNULL(sps.row_overflow_used_page_count,0) + ISNULL(sps.lob_reserved_page_count,0)) / 128.0) >= ' + CONVERT(nvarchar(MAX), @MinimumSizeMB) 
ELSE N'' END + N'
OPTION (RECOMPILE);

SELECT
	  DB_NAME()
	, p.[schema_name]
	, p.object_id
	, p.table_name
	, p.index_id
	, p.index_name
	, p.partition_number
	, p.size_MB
	, p.in_row_percent
	, range_scans_percent = ISNULL(
				FLOOR(SUM(ISNULL(ios.range_scan_count,0)) * 1.0 /
				NULLIF(SUM(
					ISNULL(ios.range_scan_count,0) +
					ISNULL(ios.leaf_delete_count,0) + 
					ISNULL(ios.leaf_insert_count,0) + 
					ISNULL(ios.leaf_page_merge_count,0) + 
					ISNULL(ios.leaf_update_count,0)
				), 0) * 100.0), 0)
	, updates_percent = ISNULL(
				CEILING(SUM(ISNULL(ios.leaf_update_count, 0)) * 1.0 /
				NULLIF(SUM(
					ISNULL(ios.range_scan_count,0) +
					ISNULL(ios.leaf_delete_count,0) + 
					ISNULL(ios.leaf_insert_count,0) + 
					ISNULL(ios.leaf_page_merge_count,0) + 
					ISNULL(ios.leaf_update_count,0)
				), 0) * 100.0), 0)
FROM #objects AS p WITH(NOLOCK)
OUTER APPLY sys.dm_db_index_operational_stats(db_id(),p.object_id,p.index_id,p.partition_number) AS ios
GROUP BY
	  p.object_id
	, p.schema_name
	, p.table_name
	, p.index_id
	, p.index_name
	, p.partition_number
	, p.size_MB
	, p.in_row_percent
OPTION (RECOMPILE, MAXDOP 1);'

INSERT INTO @ObjectsToCheck
EXEC sp_executesql @CMD;

/* end of potential for-each-db */

-- Init temp table to hold final results
IF OBJECT_ID('tempdb..#ResultsAll') IS NOT NULL DROP TABLE #ResultsAll;
CREATE TABLE #ResultsAll (
	  [database_name] SYSNAME NOT NULL
	, [schema_name] SYSNAME NOT NULL
	, [table_name] SYSNAME NOT NULL
	, [index_name] SYSNAME NULL
	, partition_number INT NULL
	, size_MB INT NULL
	, in_row_percent INT NULL
	, scan_percent INT NULL
	, update_percent INT NULL
	, compression_type VARCHAR(4) NOT NULL
	, compression_ratio FLOAT NULL
	, compression_size_saving_KB FLOAT NULL
	, is_compression_feasible BIT NULL
	, is_compression_recommended bit NULL
)

-- Init cursor to traverse all un-compressed tables that were found
DECLARE TablesToCheck CURSOR
LOCAL FORWARD_ONLY FAST_FORWARD
FOR
SELECT 
	  o.[database_name]
	, o.[schema_name]
	, o.[table_id]
	, o.[table_name]
	, o.[index_id]
	, o.[index_name]
	, o.[partition_number]
	, ct.CompressionType
	, o.size_MB
	, o.in_row_percent
	, o.range_scans_percent
	, o.updates_percent
FROM @ObjectsToCheck AS o
CROSS JOIN (VALUES('PAGE'),('ROW')) AS ct(CompressionType) -- check both ROW and PAGE compression for each

OPEN TablesToCheck

FETCH NEXT FROM TablesToCheck 
INTO @CurrDB, @Schema, @ObjectId, @Table, @IndexId, @IndexName, @Partition, @CompressionType, @TotalSizeMB, @InRowPercent, @ScanPercent, @UpdatePercent

WHILE @@FETCH_STATUS = 0
BEGIN
	DECLARE @sp_estimate_data_compression_savings NVARCHAR(1000);
	SET @sp_estimate_data_compression_savings = QUOTENAME(@CurrDB) + '.sys.sp_estimate_data_compression_savings'

	SET @EstimationCheckRecommended = CASE
						WHEN @InRowPercent < @MinimumCompressibleDataPercent THEN 0
						WHEN ISNULL(@UpdatePercent,0) <= @MaximumUpdatePctAsInfrequent THEN 1
						WHEN @CompressionType = 'PAGE' AND @ScanPercent >= @MinimumScanPctForPage AND @UpdatePercent <= @MaximumUpdatePctForPage THEN 1
						WHEN @CompressionType = 'ROW' AND @UpdatePercent <= @MaximumUpdatePctForRow THEN 1
						ELSE 0
					END

	RAISERROR(N'--Database [%s], table [%s].[%s], index [%s], partition %d: size: %d MB, in-row data: %d percent, range scans: %d percent, updates: %d percent. Compression type: %s',0,1
				,@CurrDB,@Schema,@Table,@IndexName,@Partition,@TotalSizeMB,@InRowPercent,@ScanPercent,@UpdatePercent,@CompressionType) WITH NOWAIT;

	IF @FeasibilityCheckOnly = 0 AND (@MaxSizeMBForActualCheck IS NULL OR (@TotalSizeMB <= @MaxSizeMBForActualCheck AND @TotalSizeMB * 0.05 < @AvailableTempDBSpaceMB))
	BEGIN
		IF @EstimationCheckRecommended = 1
		BEGIN
			BEGIN TRY
			
			IF @MaximumCPUPercentForRebuild IS NOT NULL
			BEGIN
				DECLARE @AvgCPU FLOAT, @WaitForCPUStartTime DATETIME;

				CpuUtilizationCheck:
					SELECT @AvgCPU = AVG( 100 - record.value('(./Record/SchedulerMonitorEvent/SystemHealth/SystemIdle)[1]', 'int') )
					FROM (
					SELECT TOP (@SamplesToCheckAvgForCPUPercent) [timestamp], convert(xml, record) as record
					FROM sys.dm_os_ring_buffers
					WHERE ring_buffer_type = N'RING_BUFFER_SCHEDULER_MONITOR'
					AND record like '%<SystemHealth>%'
					ORDER BY [timestamp] DESC
					) as RingBufferInfo

					IF @AvgCPU <= @MaximumCPUPercentForRebuild
					BEGIN
						SET @WaitForCPUStartTime = NULL;
						GOTO AfterCpuUtilizationCheck;
					END
					ELSE IF @MaximumTimeToWaitForCPU IS NOT NULL
					BEGIN
						IF @WaitForCPUStartTime IS NULL
						BEGIN
							SET @WaitForCPUStartTime = GETDATE()
						END
						ELSE IF @WaitForCPUStartTime + @MaximumTimeToWaitForCPU > GETDATE()
						BEGIN
							RAISERROR(N'-- CPU utilization is too high. Aborting check.', 16, 1);
							GOTO EndOfCursor;
						END
					END

					WAITFOR DELAY '00:00:00.5'
					GOTO CpuUtilizationCheck;
			END
			AfterCpuUtilizationCheck:

			-- Calculate compression savings estimation
			INSERT INTO @Results
			EXEC @sp_estimate_data_compression_savings
						 @schema_name		= @Schema,  
						 @object_name		= @Table,
						 @index_id		= @IndexId,
						 @partition_number	= @Partition,   
						 @data_compression	= @CompressionType;
			END TRY
			BEGIN CATCH
				DECLARE @EstimationErrMsg NVARCHAR(MAX)
				SET @EstimationErrMsg = ERROR_MESSAGE()
				RAISERROR(N'-- ERROR while running sp_estimate_data_compression_savings: %s',0,1,@EstimationErrMsg);
			END CATCH
		END
		ELSE
		BEGIN
			RAISERROR(N'-- Not a good candidate for compression. Skipping estimation check.',0,1);
			SET @ChecksSkipped = 1;
		END
	END
	ELSE IF @FeasibilityCheckOnly = 1
		SET @ChecksSkipped = 1
	ELSE
	BEGIN
		RAISERROR(N'-- Too big for TempDB. Skipping estimation check.',0,1);
		SET @ChecksSkipped = 1;
	END

	-- Save to main results table
	INSERT INTO #ResultsAll
	SELECT 
		  [database_name]		= @CurrDB
		, [schema_name]			= @Schema
		, table_name			= @Table
		, index_name			= @IndexName
		, partition_number		= @Partition
		, size_MB			= @TotalSizeMB
		, in_row_percent		= @InRowPercent
		, scan_percent			= @ScanPercent
		, update_percent		= @UpdatePercent
		, compression_type		= @CompressionType
		, compression_ratio		= 100 - (SUM(ISNULL(r.size_w_requested_compression_KB,0)) * 100.0 / NULLIF(SUM(ISNULL(r.size_w_current_compression_KB,0)),0))
		, compression_size_saving_KB	= SUM(ISNULL(r.size_w_current_compression_KB,0)) - SUM(ISNULL(r.size_w_requested_compression_KB,0))
		, is_compression_feasible	= @EstimationCheckRecommended
		, is_compression_recommended	= CASE
						WHEN @FeasibilityCheckOnly = 1 OR @EstimationCheckRecommended = 0 THEN NULL
						WHEN
							100 - (SUM(ISNULL(r.size_w_requested_compression_KB,0)) * 100.0 / NULLIF(SUM(ISNULL(r.size_w_current_compression_KB,0)),0)) >= @CompressionRatioThreshold 
						AND (SUM(ISNULL(r.size_w_current_compression_KB,0)) - SUM(ISNULL(r.size_w_requested_compression_KB,0))) / 1024.0 >= @CompressionSizeSavedMBThreshold
						THEN 1
						ELSE 0 END
	FROM
		@Results AS r
	OPTION (RECOMPILE);

	DELETE @Results;

	FETCH NEXT FROM TablesToCheck 
	INTO @CurrDB, @Schema, @ObjectId, @Table, @IndexId, @IndexName, @Partition, @CompressionType, @TotalSizeMB, @InRowPercent, @ScanPercent, @UpdatePercent
END

EndOfCursor:

CLOSE TablesToCheck
DEALLOCATE TablesToCheck

IF @ChecksSkipped = 1
BEGIN
	PRINT N'-- One or more tables were not checked. Please adjust threshold parameter values and make sure you have enough free disk space if you want to run those checks anyway.'
END

-- Return results to client
SELECT
	 [database_name]
	,[schema_name]
	,[table_name]
	,full_table_name		= QUOTENAME([schema_name]) + '.' + QUOTENAME([table_name])
	,index_name
	,partition_number		= ISNULL(CONVERT(varchar(256),partition_number),'ALL')
	,size_MB
	,compressible_data		= CONVERT(varchar(10), in_row_percent) + ' %'
	,scan_percent			= CONVERT(varchar(10), scan_percent) + ' %'
	,update_percent			= CONVERT(varchar(10), update_percent) + ' %'
	,compression_type
	,compression_ratio		= ROUND(compression_ratio,3)
	,compression_size_saving_MB	= compression_size_saving_KB / 1024.0
	,is_compression_candidate	= CASE WHEN is_compression_feasible = 1 THEN 'Yes' ELSE 'No' END
	,is_compression_recommended 	= CASE
						WHEN is_compression_recommended IS NULL AND is_compression_feasible = 1 THEN 
						  CASE
							WHEN in_row_percent < @MinimumCompressibleDataPercent THEN N'No'
							WHEN compression_type = 'PAGE' AND ISNULL(update_percent,0) <= @MaximumUpdatePctAsInfrequent THEN 'Yes'
							WHEN scan_percent >= @MinimumScanPctForPage AND update_percent <= @MaximumUpdatePctForPage THEN
								CASE WHEN compression_type = 'PAGE' THEN 'Yes' ELSE 'No' END
							WHEN update_percent <= @MaximumUpdatePctForRow THEN
								CASE WHEN compression_type = 'ROW' THEN 'Yes' ELSE 'No' END
							ELSE 'No'
						  END + ' (best guess)'
						WHEN is_compression_recommended = 1 AND SavingsRating = 1 THEN 'Yes' ELSE 'No'
					  END
	,remediation_command		= 
					CASE WHEN ISNULL(is_compression_recommended,0) = 0 OR SavingsRating <> 1 THEN N'-- ' ELSE N'' END
				+ N'USE ' + QUOTENAME([database_name]) + N'; ALTER ' + ISNULL(N'INDEX ' + QUOTENAME(index_name) + N' ON ', N'TABLE ') + QUOTENAME([schema_name]) + '.' + QUOTENAME([table_name]) 
				+ N' REBUILD PARTITION = ' + ISNULL(CONVERT(nvarchar(max),partition_number), N'ALL') 
				+ N' WITH (DATA_COMPRESSION = ' + compression_type + @RebuildOptions + N');'
FROM
(
	SELECT 
	 *, SavingsRating = ROW_NUMBER() OVER (
		PARTITION BY 
			  [database_name]
			, table_name
			, index_name 
			, partition_number
			, is_compression_recommended
		ORDER BY 
			compression_ratio + (CASE WHEN compression_type = 'ROW' THEN @MinimumRatioDifferenceForPage ELSE 0 END) DESC, 
			compression_size_saving_KB + (CASE WHEN compression_type = 'ROW' THEN ISNULL(@MinimumSavingsMBDifferenceForPage,0) * 1024.0 ELSE 0 END) DESC
		)
	FROM #ResultsAll
 ) AS r
ORDER BY
	  [database_name] ASC
	, compression_size_saving_KB DESC
	, compression_ratio DESC
	, size_MB DESC
OPTION (RECOMPILE);

IF @@ROWCOUNT > 0 AND @FeasibilityCheckOnly = 0
BEGIN
	-- Begin generating remediation script that takes into consideration all checks
	-- including ROW vs. PAGE considerations
	DECLARE @PrevDB SYSNAME;
	SET @PrevDB = N'';
	SET @CMD = NULL;
	PRINT N'-----------------------------------------------------------------------'
	PRINT N'---------- Recommendation Script Begins Below -------------------------'
	PRINT N'-----------------------------------------------------------------------'

	DECLARE Rebuilds CURSOR
	LOCAL FORWARD_ONLY FAST_FORWARD
	FOR
	SELECT
	  [database_name]
	, InsertCmd = N'INSERT INTO #INDEXTABLE VALUES (' 
			+ ISNULL(QUOTENAME([index_name], N''''), N'NULL') + N', '
			+ QUOTENAME(QUOTENAME([schema_name]) + N'.' + QUOTENAME([table_name]), N'''') + N', '
			+ ISNULL(CONVERT(nvarchar(max), partition_number), N'NULL') + N', '
			+ QUOTENAME([compression_type], N'''') + N');'
	--, RemediationCmd = N'USE ' + QUOTENAME([database_name]) + N'; ALTER ' + ISNULL(N'INDEX ' + QUOTENAME(index_name) + N' ON ', N'TABLE ') + QUOTENAME([schema_name]) + '.' + QUOTENAME([table_name]) + N'
	--REBUILD PARTITION = ' + ISNULL(CONVERT(nvarchar,partition_number), N'ALL') + N' WITH (DATA_COMPRESSION = ' + compression_type + @RebuildOptions + N');'
	--, StatusMessage = QUOTENAME([database_name]) + N': ' + ISNULL(N'INDEX ' + QUOTENAME(index_name) + N' ON ', N'TABLE ') + QUOTENAME([schema_name]) + N'.' + QUOTENAME([table_name])
	--				+ N' PARTITION = ' + ISNULL(CONVERT(nvarchar,partition_number), N'ALL') + N', DATA_COMPRESSION = ' + compression_type
	FROM
	(
	SELECT
	  [database_name]
	, [schema_name]
	, table_name
	, index_name
	, compression_size_saving_KB
	, compression_ratio
	, compression_type
	, partition_number
	, SavingsRating = ROW_NUMBER() OVER (
				PARTITION BY 
					  [database_name]
					, table_name
					, index_name 
					, partition_number
				ORDER BY 
					compression_ratio + (CASE WHEN compression_type = 'ROW' THEN @MinimumRatioDifferenceForPage ELSE 0 END) DESC, 
					compression_size_saving_KB + (CASE WHEN compression_type = 'ROW' THEN ISNULL(@MinimumSavingsMBDifferenceForPage,0) * 1024.0 ELSE 0 END) DESC
				)
	FROM
		#ResultsAll
	WHERE
		is_compression_recommended = 1
	) AS q
	WHERE SavingsRating = 1
	ORDER BY
	  [database_name] ASC
	, compression_size_saving_KB DESC
	, compression_ratio DESC

	OPEN Rebuilds
	FETCH NEXT FROM Rebuilds INTO @CurrDB, @CMD

	WHILE @@FETCH_STATUS = 0
	BEGIN
		IF @CurrDB <> @PrevDB
		BEGIN
			PRINT N'USE ' + QUOTENAME(@CurrDB) + N';
DECLARE @Size INT, @DB SYSNAME;
SELECT @Size = SUM(FILEPROPERTY([name], ''SpaceUsed'')) / 128.0 FROM sys.database_files WHERE type = 0;
SET @DB = DB_NAME();

RAISERROR(N''Space used for data in "%s" BEFORE compression: %d MB'', 0, 1, @DB, @Size) WITH NOWAIT;
GO
SET NOCOUNT, QUOTED_IDENTIFIER, ARITHABORT, XACT_ABORT ON;
IF OBJECT_ID(''tempdb..#INDEXTABLE'') IS NOT NULL DROP TABLE #INDEXTABLE;
CREATE TABLE #INDEXTABLE (
	IndexName SYSNAME NULL, 
	TableName NVARCHAR(4000) NOT NULL,
	PartitionNumber INT NULL,
	CompressionType SYSNAME NOT NULL
)
'
			SET @PrevDB = @CurrDB;
		END

		PRINT @CMD;

		FETCH NEXT FROM Rebuilds INTO @CurrDB, @CMD;
		
		IF @@FETCH_STATUS <> 0 OR @CurrDB <> @PrevDB
		BEGIN
			PRINT N'GO
USE ' + QUOTENAME(@PrevDB) + N';

DECLARE @WhatIf BIT = 0

SET NOCOUNT, QUOTED_IDENTIFIER, ARITHABORT, XACT_ABORT ON;
DECLARE @DB SYSNAME;
SET @DB = DB_NAME();
DECLARE @time VARCHAR(25)
DECLARE @IndexName SYSNAME, @TableName NVARCHAR(4000), @PartitionNumber INT, @CompressionType SYSNAME, @CMD NVARCHAR(MAX)'

			PRINT N'DECLARE TablesToCheck CURSOR
LOCAL FORWARD_ONLY FAST_FORWARD
FOR
SELECT IndexName, TableName, PartitionNumber, CompressionType,
	Cmd = N''USE '' + QUOTENAME(@DB) + N''; ALTER '' + ISNULL(N''INDEX '' + QUOTENAME(IndexName) + N'' ON '', N''TABLE '') + TableName 
	+ N'' REBUILD PARTITION = '' + ISNULL(CONVERT(nvarchar,PartitionNumber), N''ALL'') 
	+ N'' WITH (DATA_COMPRESSION = '' + CompressionType + N''' + @RebuildOptions + N');''
FROM #INDEXTABLE

OPEN TablesToCheck

WHILE 1 = 1
BEGIN
	FETCH NEXT FROM TablesToCheck INTO @IndexName, @TableName, @PartitionNumber, @CompressionType, @CMD

	IF @@FETCH_STATUS <> 0
		BREAK;'

	IF @AllowedRuntimeHourFrom IS NOT NULL AND @AllowedRuntimeHourTo IS NOT NULL
		PRINT N'
	IF DATEPART(hour, GETDATE()) NOT BETWEEN ' + CONVERT(nvarchar(MAX), @AllowedRuntimeHourFrom) + N' AND ' + CONVERT(nvarchar(MAX), @AllowedRuntimeHourTo) + N'
	BEGIN
		SET @time = CONVERT(VARCHAR(25), GETDATE(), 121);
		RAISERROR(N''%s - Reached outside allowed execution time.'', 0, 1, @time);
		BREAK;
	END'

	IF @NotAllowedRuntimeHourFrom IS NOT NULL AND @NotAllowedRuntimeHourTo IS NOT NULL
		PRINT N'
	IF DATEPART(hour, GETDATE()) BETWEEN ' + CONVERT(nvarchar(MAX), @NotAllowedRuntimeHourFrom) + N' AND ' + CONVERT(nvarchar(MAX), @NotAllowedRuntimeHourTo) + N'
	BEGIN
		SET @time = CONVERT(VARCHAR(25), GETDATE(), 121);
		RAISERROR(N''%s - Reached outside allowed execution time.'', 0, 1, @time);
		BREAK;
	END'

	IF @MaximumCPUPercentForRebuild IS NOT NULL
	PRINT N'
	DECLARE @AvgCPU FLOAT, @WaitForCPUStartTime DATETIME;

	CpuUtilizationCheck:
		SELECT @AvgCPU = AVG( 100 - record.value(''(./Record/SchedulerMonitorEvent/SystemHealth/SystemIdle)[1]'', ''int'') )
		from (
		SELECT TOP (' + CONVERT(nvarchar(MAX), @SamplesToCheckAvgForCPUPercent) + N') [timestamp], convert(xml, record) as record
		FROM sys.dm_os_ring_buffers
		WHERE ring_buffer_type = N''RING_BUFFER_SCHEDULER_MONITOR''
		AND record like ''%<SystemHealth>%''
		ORDER BY [timestamp] DESC
		) as RingBufferInfo

		IF @AvgCPU <= ' + CONVERT(nvarchar(MAX), @MaximumCPUPercentForRebuild) + N'
		BEGIN
			SET @WaitForCPUStartTime = NULL;
		END' + CASE WHEN @MaximumTimeToWaitForCPU IS NOT NULL THEN N'
		ELSE IF @WaitForCPUStartTime IS NULL
		BEGIN
			SET @WaitForCPUStartTime = GETDATE()
			GOTO CpuUtilizationCheck;
		END
		ELSE IF @WaitForCPUStartTime + ' + QUOTENAME(CONVERT(nvarchar(max), @MaximumTimeToWaitForCPU, 121), N'''') + N' > GETDATE()
		BEGIN
			SET @time = CONVERT(VARCHAR(25), GETDATE(), 121);
			RAISERROR(N''%s - CPU utilization is too high.'', 0, 1, @time);
			BREAK;
		END' ELSE N'' END +  N'
		ELSE
		BEGIN
			WAITFOR DELAY ''00:00:00.5''
			GOTO CpuUtilizationCheck;
		END'

	PRINT N'

	-- Check if index has no compression
	IF EXISTS (
	SELECT NULL
	FROM sys.partitions AS p WITH (NOLOCK)
	INNER JOIN sys.indexes AS ix WITH (NOLOCK)
		ON ix.object_id = p.object_id
		AND ix.index_id = p.index_id
	WHERE ix.object_id = OBJECT_ID(@TableName)
	AND (ix.name = @IndexName OR (@IndexName IS NULL AND ix.index_id = 0))
	AND p.data_compression_desc <> @CompressionType
	AND (@PartitionNumber IS NULL OR p.partition_number = @PartitionNumber)
	)
	BEGIN
		SET @time = CONVERT(VARCHAR(25), GETDATE(), 121);
		RAISERROR (N''%s - [%s]: INDEX [%s] ON %s PARTITION = %s, DATA_COMPRESSION = %s'', 0, 1, @time, @DB, @IndexName, @TableName, @PartitionNumber, @CompressionType) WITH NOWAIT;
		PRINT @CMD;
		IF @WhatIf = 0 EXEC sp_executesql @CMD;
	END

END

CLOSE TablesToCheck
DEALLOCATE TablesToCheck

DROP TABLE #INDEXTABLE

GO'
			PRINT N'USE ' + QUOTENAME(@PrevDB) + N';
DECLARE @Size INT, @DB SYSNAME;
SET @DB = DB_NAME();
SELECT @Size = SUM(FILEPROPERTY([name], ''SpaceUsed'')) / 128.0 FROM sys.database_files WHERE type = 0;

RAISERROR(N''Space used for data in "%s" AFTER compression: %d MB'', 0, 1, @DB, @Size) WITH NOWAIT;
GO'
		END --IF @@FETCH_STATUS <> 0 OR @CurrDB <> @PrevDB
	END -- WHILE @@FETCH_STATUS = 0
	PRINT N'DECLARE @time VARCHAR(25) = CONVERT(varchar(25), GETDATE(), 121); RAISERROR(N''%s - Done'',0,1,@time) WITH NOWAIT;'

	CLOSE Rebuilds
	DEALLOCATE Rebuilds

	PRINT N'-----------------------------------------------------------------------'
	PRINT N'----------- Recommendation Script Ends Here  --------------------------'
	PRINT N'-----------------------------------------------------------------------'
END
ELSE IF @FeasibilityCheckOnly = 1
BEGIN
	PRINT N'-----------------------------------------------------------------------'
	PRINT N'-------- Feasibility Check Only - No Script Generated -----------------'
	PRINT N'-----------------------------------------------------------------------'
END
ELSE
BEGIN
	PRINT N'-----------------------------------------------------------------------'
	PRINT N'----------- No Candidates for Compression Found -----------------------'
	PRINT N'-----------------------------------------------------------------------'
END

PRINT N'GO'

Quit:

Thank you very much for creating this. It saved me a lot of time and you went way beyond being a minimal implementation.

I think it would would be a nice addition if the script could determine that the best action for a table, which is ROW/PAGE compressed, is to reverted back to no compression. The same goes for reverting a PAGE compression back to ROW compression, if that is not already implemented.

Hi @drasive ,
Thank you for your feedback! I'm glad that you found this script useful.

That's an interesting idea to add a calculation to determine whether compression should be reverted.
However, that would likely require a significant code change, and I'm not certain that it really justifies the effort.

As for reverting from PAGE compression back to ROW compression, you should check out the following blog post:

https://eitanblumin.com/2022/01/17/detect-low-compression-rates-in-all-databases/

Thank you for the script!
Why do I have some index names NULL, I'm on SQL Server 2019 Enterprise.

--Database [test], table [dbo].[testtable], index [(null)], partition (null): size: 586 MB, in-row data: 99 percent, range scans: 3 percent, updates: 0 percent. Compression type: PAGE

Thank you for the script! Why do I have some index names NULL, I'm on SQL Server 2019 Enterprise.

--Database [test], table [dbo].[testtable], index [(null)], partition (null): size: 586 MB, in-row data: 99 percent, range scans: 3 percent, updates: 0 percent. Compression type: PAGE

Hi acscott, when an index is specified as null, it means it's a heap table.

Makes sense! Thank you! 😃