/* Azure SQL Maintenance - Maintenance script for Azure SQL Database */
/* This script provided AS IS, Please review the code before executing this on production environment */
/* For any issue or suggestion please email to: yocr@microsoft.com */
/* 
***********************************************
	Current Version Date: 2024-04-18
***********************************************

Change Log: 
	2024-04-18 - Add internal variable to control SORT_IN_TEMPDB, change the way alter index command is being build to make it more flexible.
	2023-07-13 - KB4551220 - skip resumable operation for indexes that has filter
	2022-11-08 - Ignore table value functions for index maintenance Thanks to https://github.com/Mitch-Wheat for suggesting that
	2022-10-06 - Fix help text that was mixed up, thanks Holger for pointing that out.
	2022-10-03 - Add [whatif] as the first debug option, fix - do not skip stats for reorganize.
	2022-04-25 - Set data type for @debug to nvarchar(10) as per comment I got from Paul McMillan - note that @debug is not in use at the moment.
	2022-01-30 - As per comment from Tariq, removing dbo schema name from procedure and use user default.
	2021-12-08 - Fix issue #19 on GitGub
	2021-01-07
			+ some bug fixes - see GitHub for more information 
*/

if object_id('AzureSQLMaintenance') is null
	exec('create procedure AzureSQLMaintenance as /*dummy procedure body*/ select 1;')	
GO
ALTER PROCEDURE [AzureSQLMaintenance]
	(
		@operation nvarchar(10) = null,
		@mode nvarchar(10) = 'smart',
		@ResumableIndexRebuild bit = 0,
		@RebuildHeaps bit = 0,
		@LogToTable bit = 0,
		@debug nvarchar(10) = 'off'
	)
as
begin
	set nocount on;
	
	---------------------------------------------
	--- Varialbles and pre conditions check
	---------------------------------------------

	set quoted_identifier on;
	declare @idxIdentifierBegin char(1), @idxIdentifierEnd char(1);
	declare @statsIdentifierBegin char(1), @statsIdentifierEnd char(1);
	
	declare @msg nvarchar(max);
	declare @minPageCountForIndex int = 40;
	declare @OperationTime datetime2 = sysdatetime();
	declare @KeepXOperationInLog int =3;
	declare @ScriptHasAnError int = 0; 
	declare @ResumableIndexRebuildSupported int;
	declare @indexStatsMode sysname;
	declare @LowFragmentationBoundry int = 5;
	declare @HighFragmentationBoundry int = 30;
	declare @SORT_IN_TEMPDB bit = 1; /* 1=Activate SORT_IN_TEMPDB , 0= do not activate SORT_IN_TEMPDB  while rebuilding indexes */

	/* make sure parameters selected correctly */
	set @operation = lower(@operation)
	set @mode = lower(@mode)
	set @debug = lower(@debug) 
	
	if @mode not in ('smart','dummy')
		set @mode = 'smart'

	---------------------------------------------
	--- Begin
	---------------------------------------------

	if @operation not in ('index','statistics','all') or @operation is null
	begin
		raiserror('@operation (varchar(10)) [mandatory]',0,0)
		raiserror(' Select operation to perform:',0,0)
		raiserror('     "index" to perform index maintenance',0,0)
		raiserror('     "statistics" to perform statistics maintenance',0,0)
		raiserror('     "all" to perform indexes and statistics maintenance',0,0)
		raiserror(' ',0,0)
		raiserror('@mode(varchar(10)) [optional]',0,0)
		raiserror(' optionaly you can supply second parameter for operation mode: ',0,0)
		raiserror('     "smart" (Default) using smart decision about what index or stats should be touched.',0,0)
		raiserror('     "dummy" going through all indexes and statistics regardless thier modifications or fragmentation.',0,0)
		raiserror(' ',0,0)
		raiserror('@ResumableIndexRebuild(bit) [optional]',0,0)
		raiserror(' Optionaly you can choose to rebuild indexes as resumable operation: ',0,0)
		raiserror('     "0" (Default) using non resumable index rebuild.',0,0)
		raiserror('     "1" using resumable index rebuild when it is supported.',0,0)
		raiserror(' ',0,0)
		raiserror('@RebuildHeaps(bit) [optional]',0,0)
		raiserror(' Rebuild HEAPS to fix forwarded records issue on tables with no clustered index',0,0)
		raiserror('     0 - (Default) do not rebuild heaps',0,0)
		raiserror('     1 - Rebuild heaps based on @mode parameter, @mode=dummy will rebuild all heaps',0,0)
		raiserror(' ',0,0)
		raiserror('@LogToTable(bit) [optional]',0,0)
		raiserror(' Optionaly allows you to turn on logging ',0,0)
		raiserror('     0 - (Default) do not log operation to table',0,0)
		raiserror('     1 - log operation to table',0,0)
		raiserror('		for logging option only 3 last execution will be kept by default. this can be changed by easily in the procedure body.',0,0)
		raiserror('		Log table will be created automatically if not exists.',0,0)
		raiserror(' ',0,0)
		raiserror('@debug [optional]',0,0)
		raiserror(' Allows debugging feature.',0,0)
		raiserror('     off - (Default) debug option is off',0,0)
		raiserror('     whatif - Remark all commands so it will not be executed, helps with understanding the commands to be executed',0,0)
		raiserror('     * in any case debug is used there will be user tables created to help with reviewing the process. cmdQueue, idxBefore and statsBefore ',0,0)
		raiserror(' ',0,0)
		raiserror('Example:',0,0)
		raiserror('		exec  AzureSQLMaintenance ''all'', @LogToTable=1',0,0)
	end
	else 
	begin
		
		---------------------------------------------
		--- Prepare log table
		---------------------------------------------

		/* Prepare Log Table */
		if object_id('AzureSQLMaintenanceLog') is null and @LogToTable=1
		begin
			create table AzureSQLMaintenanceLog (id bigint primary key identity(1,1), OperationTime datetime2, command varchar(4000),ExtraInfo varchar(4000), StartTime datetime2, EndTime datetime2, StatusMessage varchar(1000));
		end

		---------------------------------------------
		--- Resume operation
		---------------------------------------------

		/*Check is there is operation to resume*/
		if OBJECT_ID('AzureSQLMaintenanceCMDQueue') is not null 
		begin
			if 
				/*resume information exists*/ exists(select * from AzureSQLMaintenanceCMDQueue where ID=-1) 
			begin
				/*resume operation confirmed*/
				set @operation='resume' -- set operation to resume, this can only be done by the proc, cannot get this value as parameter

				-- restore operation parameters 
				select top 1
				@LogToTable = JSON_VALUE(ExtraInfo,'$.LogToTable')
				,@mode = JSON_VALUE(ExtraInfo,'$.mode')
				,@ResumableIndexRebuild = JSON_VALUE(ExtraInfo,'$.ResumableIndexRebuild')
				from AzureSQLMaintenanceCMDQueue 
				where ID=-1
				
				raiserror('-----------------------',0,0)
				set @msg = 'Resuming previous operation'
				raiserror(@msg,0,0)
				raiserror('-----------------------',0,0)
			end
			else
				begin
					-- table [AzureSQLMaintenanceCMDQueue] exist but resume information does not exists
					-- this might happen in case execution intrupted between collecting index & ststistics information and executing commands.
					-- to fix that we drop the table now, it will be recreated later 
					DROP TABLE [AzureSQLMaintenanceCMDQueue];
				end
		end


		---------------------------------------------
		--- Report operation parameters
		---------------------------------------------
		
		/*Write operation parameters*/
		raiserror('-----------------------',0,0)
		set @msg = 'set operation = ' + @operation;
		raiserror(@msg,0,0)
		set @msg = 'set mode = ' + @mode;
		raiserror(@msg,0,0)
		set @msg = 'set ResumableIndexRebuild = ' + cast(@ResumableIndexRebuild as varchar(1));
		raiserror(@msg,0,0)
		set @msg = 'set RebuildHeaps = ' + cast(@RebuildHeaps as varchar(1));
		raiserror(@msg,0,0)
		set @msg = 'set LogToTable = ' + cast(@LogToTable as varchar(1));
		raiserror(@msg,0,0)
		set @msg = 'set debug = ' + @debug;
		raiserror(@msg,0,0)
		raiserror('-----------------------',0,0)
	end

	if @LogToTable=1 insert into AzureSQLMaintenanceLog values(@OperationTime,null,null,sysdatetime(),sysdatetime(),'Starting operation: Operation=' +@operation + ' Mode=' + @mode + ' Keep log for last ' + cast(@KeepXOperationInLog as varchar(10)) + ' operations' )	

	-- create command queue table, if there table exits then we resume operation in earlier stage.
	if @operation!='resume'
		create table AzureSQLMaintenanceCMDQueue (ID int identity primary key,txtCMD nvarchar(max),ExtraInfo varchar(max))

	---------------------------------------------
	--- Check if engine support resumable index operation
	---------------------------------------------
	if @ResumableIndexRebuild=1 
	begin
		if cast(SERVERPROPERTY('EngineEdition')as int)>=5 or cast(SERVERPROPERTY('ProductMajorVersion')as int)>=14
		begin
			set @ResumableIndexRebuildSupported=1;
		end
		else
		begin 
				set @ResumableIndexRebuildSupported=0;
				set @msg = 'Resumable index rebuild is not supported on this database'
				raiserror(@msg,0,0)
				if @LogToTable=1 insert into AzureSQLMaintenanceLog values(@OperationTime,null,null,sysdatetime(),sysdatetime(),@msg)	
		end
	end


	---------------------------------------------
	--- Index maintenance
	---------------------------------------------
	if @operation in('index','all')
	begin
		/**/
		if @mode='smart' and @RebuildHeaps=1 
			set @indexStatsMode = 'SAMPLED'
		else
			set @indexStatsMode = 'LIMITED'
	
		raiserror('Get index information...(wait)',0,0) with nowait;
		/* Get Index Information */
		/* using inner join - this eliminates indexes that we cannot maintain such as indexes on functions */
		select 
			idxs.[object_id]
			,ObjectSchema = OBJECT_SCHEMA_NAME(idxs.object_id)
			,ObjectName = object_name(idxs.object_id) 
			,IndexName = idxs.name
			,idxs.type
			,idxs.type_desc
			,idxs.has_filter
			,i.avg_fragmentation_in_percent
			,i.page_count
			,i.index_id
			,i.partition_number
			,i.avg_page_space_used_in_percent
			,i.record_count
			,i.ghost_record_count
			,i.forwarded_record_count
			,null as OnlineOpIsNotSupported
			,null as ObjectDoesNotSupportResumableOperation
			,cast(0 as bit) as SortInTempDB
			,case when ps.data_space_id IS NULL then 0 else 1 end as IsPartitioned
			,0 as SkipIndex
			,replicate(' ',20)  as OperationToTake 
			,replicate(' ',128) as SkipReason
		into #idxBefore
		from sys.indexes idxs 
		left join sys.partition_schemes ps ON idxs.data_space_id = ps.data_space_id
		inner join sys.objects obj on idxs.object_id = obj.object_id
		inner join sys.dm_db_index_physical_stats(DB_ID(),NULL, NULL, NULL ,@indexStatsMode) i  on i.object_id = idxs.object_id and i.index_id = idxs.index_id
		where idxs.type in (0 /*HEAP*/,1/*CLUSTERED*/,2/*NONCLUSTERED*/,5/*CLUSTERED COLUMNSTORE*/,6/*NONCLUSTERED COLUMNSTORE*/) 
		and (alloc_unit_type_desc = 'IN_ROW_DATA' /*avoid LOB_DATA or ROW_OVERFLOW_DATA*/ or alloc_unit_type_desc is null /*for ColumnStore indexes*/)
		and OBJECT_SCHEMA_NAME(idxs.object_id) != 'sys'
		and idxs.is_disabled=0
		and obj.type_desc != 'TF' /* Ignore table value functions */
		order by i.avg_fragmentation_in_percent desc, i.page_count desc
				
		-- mark indexes XML,spatial and columnstore not to run online update 
		update #idxBefore set OnlineOpIsNotSupported=1 where [object_id] in (select [object_id] from #idxBefore where [type]=3 /*XML Indexes*/)

		-- mark clustered indexes for tables with 'text','ntext','image' to rebuild offline
		update #idxBefore set OnlineOpIsNotSupported=1 
		where index_id=1 /*clustered*/ and [object_id] in (
			select object_id
			from sys.columns c join sys.types t on c.user_type_id = t.user_type_id
			where t.name in ('text','ntext','image')
		)
	
		-- do all as offline for box edition that does not support online
		update #idxBefore set OnlineOpIsNotSupported=1  
			where /* Editions that does not support online operation in case this has been used with on-prem server */
				convert(varchar(100),serverproperty('Edition')) like '%Express%' 
				or convert(varchar(100),serverproperty('Edition')) like '%Standard%'
				or convert(varchar(100),serverproperty('Edition')) like '%Web%'
		
		-- Do non resumable operation when index contains computed column or timestamp data type
		update idx set ObjectDoesNotSupportResumableOperation=1
		from #idxBefore idx join sys.index_columns ic on idx.object_id = ic.object_id and idx.index_id=ic.index_id
		join sys.columns c on ic.object_id=c.object_id and ic.column_id=c.column_id
		where c.is_computed=1 or system_type_id=189 /*TimeStamp column*/

		-- Disable resumable operation for indexes that has filter (filtered indexes) (KB4551220)
		update idx set ObjectDoesNotSupportResumableOperation=1
		from #idxBefore idx 
		where idx.has_filter=1
		
		-- set SkipIndex=1 if conditions for maintenance are not met
		-- this is used to idntify if stats need to be updated or not. 
		-- Check#1 - if table is too small
		update #idxBefore set SkipIndex=1,SkipReason='Maintenance is not needed as table is too small'
		where (
					/*Table is small*/
					(page_count<=@minPageCountForIndex)
				)
				and @mode != 'dummy' /*for Dummy mode we do not want to skip anything */
		
		-- Check#2 - if table is not small and fragmentation % is too low 
		update #idxBefore set SkipIndex=1,SkipReason='Maintenance is not needed as fragmentation % is low'
		where (
					/*Table is big enough - but fragmentation is less than 5%*/
					(page_count>@minPageCountForIndex and avg_fragmentation_in_percent<@LowFragmentationBoundry)
				)
				and @mode != 'dummy' /*for Dummy mode we do not want to skip anything */
		
		-- Skip columnstore indexes
		update #idxBefore set SkipIndex=1,SkipReason='Columnstore index'
		where (
					type in (
								5/*Clustered columnstore index*/,
								6/*Nonclustered columnstore index*/
							)
				)
				and @mode != 'dummy' /*for Dummy mode we do not want to skip anything */

		/***/
		update #idxBefore set OperationToTake = 
			case when
			(
				avg_fragmentation_in_percent between @LowFragmentationBoundry and @HighFragmentationBoundry and @mode = 'smart')/* index fragmentation condition */ 
				or 
				(@mode='dummy' and type in (5,6))/* Columnstore indexes in dummy mode -> reorganize them */
			then
				 'REORGANIZE'
			else 
				'REBUILD'
			end

		-- Choose when to do SORT_IN_TEMPDB, based on variable and if resumable operation is used as SORT_IN_TEMPDB is not supported for resumable operations.
		update idx set SortInTempDB=1
		from #idxBefore idx 
		where 
			(
				/* Internal variable instrusts to use SORT_IN_TEMPDB and resumable operation was not activated*/
				/* Resumable operation cannot use sort in tempDB as tempdb is nor persisted*/
				@SORT_IN_TEMPDB=1 and @ResumableIndexRebuild = 0 
			)
		
		raiserror('---------------------------------------',0,0) with nowait
		raiserror('Index Information:',0,0) with nowait
		raiserror('---------------------------------------',0,0) with nowait

		select @msg = count(*) from #idxBefore 
		set @msg = 'Total Indexes: ' + @msg
		raiserror(@msg,0,0) with nowait

		select @msg = avg(avg_fragmentation_in_percent) from #idxBefore where page_count>@minPageCountForIndex
		set @msg = 'Average Fragmentation: ' + @msg
		raiserror(@msg,0,0) with nowait

		select @msg = sum(iif(avg_fragmentation_in_percent>=@LowFragmentationBoundry and page_count>@minPageCountForIndex,1,0)) from #idxBefore 
		set @msg = 'Fragmented Indexes: ' + @msg
		raiserror(@msg,0,0) with nowait

				
		raiserror('---------------------------------------',0,0) with nowait


		/* Choose the identifier to be used based on existing object name 
			this came up from object that contains '[' within the object name
			such as "EPK[export].[win_sourceofwealthbpf]" as index name
			if we use '[' as identifier it will cause wrong identifier name	
		*/
		if exists(
			select 1
			from #idxBefore 
			where IndexName like '%[%' or IndexName like '%]%'
			or ObjectSchema like '%[%' or ObjectSchema like '%]%'
			or ObjectName like '%[%' or ObjectName like '%]%'
			)
		begin
			set @idxIdentifierBegin = '"'
			set @idxIdentifierEnd = '"'
		end
		else 
		begin
			set @idxIdentifierBegin = '['
			set @idxIdentifierEnd = ']'
		end

			
		/* create queue for indexes */
		insert into AzureSQLMaintenanceCMDQueue(txtCMD,ExtraInfo)
		select 
		txtCMD = 'ALTER INDEX ' + @idxIdentifierBegin + IndexName + @idxIdentifierEnd + ' ON '+ @idxIdentifierBegin + ObjectSchema + @idxIdentifierEnd +'.'+ @idxIdentifierBegin + ObjectName + @idxIdentifierEnd + ' ' +
		OperationToTake+ ' ' + 
		case when IsPartitioned = 1 then 'PARTITION=' + CAST(partition_number AS varchar(10)) + ' ' else '' end +
		case when OperationToTake='REBUILD' 
			then 'WITH(MAXDOP=1'  + 
			case when OnlineOpIsNotSupported=1 then ',ONLINE=OFF' else ',ONLINE=ON' end +
			case when @ResumableIndexRebuild=1 and @ResumableIndexRebuildSupported=1 and ObjectDoesNotSupportResumableOperation=0 then ',RESUMABLE=ON' else ',RESUMABLE=OFF' end + 
			case when SortInTempDB=1 then ',SORT_IN_TEMPDB=ON' else ',SORT_IN_TEMPDB=OFF' end +
			')' 
			else /* Operation is reoranize*/ '' end + 
		';'
		, ExtraInfo =
			'Taking Action: ' + OperationToTake + ' ' + 
			case when type in (5,6) then
				'Dummy mode therefore reorganize columnstore indexes'
			else 
				'Current fragmentation: ' + format(avg_fragmentation_in_percent/100,'p')+ ' with ' + cast(page_count as nvarchar(20)) + ' pages'
			end
		from #idxBefore
		where SkipIndex=0 and type != 0 /*Avoid HEAPS*/


		---------------------------------------------
		--- Index - Heaps 
		---------------------------------------------

		/* create queue for heaps */
		if @RebuildHeaps=1 
		begin
			insert into AzureSQLMaintenanceCMDQueue(txtCMD,ExtraInfo)
			select 
			txtCMD = 'ALTER TABLE ' + @idxIdentifierBegin + ObjectSchema + @idxIdentifierEnd +'.'+ @idxIdentifierBegin + ObjectName + @idxIdentifierEnd + ' REBUILD ' + 
			case when IsPartitioned = 1 then 'PARTITION=' + CAST(partition_number AS varchar(10)) + ' ' else '' end + ';' 
			, ExtraInfo = 'Rebuilding heap - forwarded records ' + cast(forwarded_record_count as varchar(100)) + ' out of ' + cast(record_count as varchar(100)) + ' record in the table'
			from #idxBefore
			where
				type = 0 /*heaps*/
				and 
					(
						@mode='dummy' 
						or 
						(forwarded_record_count/nullif(record_count,0)>0.3) /* 30% of record count */
						or
						(forwarded_record_count>105000) /* for tables with > 350K rows dont wait for 30%, just run yje maintenance once we reach the 100K forwarded records */
					)
		end /* create queue for heaps */
	end



	---------------------------------------------
	--- Statistics maintenance
	---------------------------------------------

	if @operation in('statistics','all')
	begin 
		/*Gets Stats for database*/
		raiserror('Get statistics information...',0,0) with nowait;
		select 
			ObjectSchema = OBJECT_SCHEMA_NAME(s.object_id)
			,ObjectName = object_name(s.object_id) 
			,s.object_id
			,s.stats_id
			,StatsName = s.name
			,sp.last_updated
			,sp.rows
			,sp.rows_sampled
			,sp.modification_counter
			, i.type
			, i.type_desc
			,0 as SkipStatistics
		into #statsBefore
		from sys.stats s cross apply sys.dm_db_stats_properties(s.object_id,s.stats_id) sp 
		left join sys.indexes i on sp.object_id = i.object_id and sp.stats_id = i.index_id
		where OBJECT_SCHEMA_NAME(s.object_id) != 'sys' and /*Modified stats or Dummy mode*/(isnull(sp.modification_counter,0)>0 or @mode='dummy')
		order by sp.last_updated asc

		/*Remove statistics if it is handled by index rebuild 
		When index is rebuild we already update stats as part of the rebuild -> therefore I am skipping this index
		for reorganize or for indexes with low fragmentation we do not update stats*/
		if @operation= 'all'
		update _stats set SkipStatistics=1 
			from #statsBefore _stats
			join #idxBefore _idx
			on _idx.ObjectSchema = _stats.ObjectSchema
			and _idx.ObjectName = _stats.ObjectName
			and _idx.IndexName = _stats.StatsName 
			where _idx.SkipIndex=0 and _idx.OperationToTake='REBUILD'

		/*Skip statistics for Columnstore indexes*/
		update #statsBefore set SkipStatistics=1
		where type in (5,6) /*Column store indexes*/

		/*Skip statistics if resumable operation is pause on the same object*/
		if @ResumableIndexRebuildSupported=1
		begin
			update _stats set SkipStatistics=1
			from #statsBefore _stats join sys.index_resumable_operations iro on _stats.object_id=iro.object_id and _stats.stats_id=iro.index_id
		end
		
		raiserror('---------------------------------------',0,0) with nowait
		raiserror('Statistics Information:',0,0) with nowait
		raiserror('---------------------------------------',0,0) with nowait

		select @msg = sum(modification_counter) from #statsBefore
		set @msg = 'Total Modifications: ' + @msg
		raiserror(@msg,0,0) with nowait
		
		select @msg = sum(iif(modification_counter>0,1,0)) from #statsBefore
		set @msg = 'Modified Statistics: ' + @msg
		raiserror(@msg,0,0) with nowait
				
		raiserror('---------------------------------------',0,0) with nowait

		/* Choose the identifier to be used based on existing object name */
		if exists(
			select 1
			from #statsBefore 
			where StatsName like '%[%' or StatsName like '%]%'
			or ObjectSchema like '%[%' or ObjectSchema like '%]%'
			or ObjectName like '%[%' or ObjectName like '%]%'
			)
		begin
			set @statsIdentifierBegin = '"'
			set @statsIdentifierEnd = '"'
		end
		else 
		begin
			set @statsIdentifierBegin = '['
			set @statsIdentifierEnd = ']'
		end
		
		/* create queue for update stats */
		insert into AzureSQLMaintenanceCMDQueue(txtCMD,ExtraInfo)
		select 
		txtCMD = 'UPDATE STATISTICS '+ @statsIdentifierBegin + ObjectSchema + +@statsIdentifierEnd + '.'+@statsIdentifierBegin + ObjectName + @statsIdentifierEnd +' (' + @statsIdentifierBegin + StatsName + @statsIdentifierEnd + ') WITH FULLSCAN;'
		, ExtraInfo = '#rows:' + cast([rows] as varchar(100)) + ' #modifications:' + cast(modification_counter as varchar(100)) + ' modification percent: ' + format((1.0 * modification_counter/ rows ),'p')
		from #statsBefore
		where SkipStatistics=0;
	end

	if @operation in('statistics','index','all','resume')
	begin

		declare @SQLCMD nvarchar(max);
		declare @ID int;
		declare @ExtraInfo nvarchar(max);
	
		/*handle debug options*/
		if @debug!='off'
		begin
			
			/*When whatif is used remark all commands*/
			if @debug='whatif' 
			begin
				update AzureSQLMaintenanceCMDQueue set txtCMD = '--' + txtCMD
			end
			
			/*keep debug table snapshot*/
			drop table if exists idxBefore
			drop table if exists statsBefore
			drop table if exists cmdQueue
			if object_id('tempdb..#idxBefore') is not null select * into idxBefore from #idxBefore
			if object_id('tempdb..#statsBefore') is not null select * into statsBefore from #statsBefore
			if object_id('AzureSQLMaintenanceCMDQueue') is not null select * into cmdQueue from AzureSQLMaintenanceCMDQueue
		end
		
		/*Save current execution parameters in case resume is needed */
		if @operation!='resume'
		begin
			set @ExtraInfo = (select top 1 LogToTable = @LogToTable, operation=@operation, operationTime=@OperationTime, mode=@mode, ResumableIndexRebuild = @ResumableIndexRebuild from sys.tables for JSON path, WITHOUT_ARRAY_WRAPPER)
			set identity_insert AzureSQLMaintenanceCMDQueue on
			insert into AzureSQLMaintenanceCMDQueue(ID,txtCMD,ExtraInfo) values(-1,'parameters to be used by resume code path',@ExtraInfo)
			set identity_insert AzureSQLMaintenanceCMDQueue off
		end
	
		---------------------------------------------
		--- Executing commands
		---------------------------------------------
		/*
		needed to rebuild indexes on comuted columns
		if ANSI_WARNINGS is set to OFF we might get the followin exception:
			Msg 1934, Level 16, State 1, Line 2
			ALTER INDEX failed because the following SET options have incorrect settings: 'ANSI_WARNINGS'. Verify that SET options are correct for use with indexed views and/or indexes on computed columns and/or filtered indexes and/or query notifications and/or XML data type methods and/or spatial index operations.
		*/
		SET ANSI_WARNINGS ON;

		raiserror('Start executing commands...',0,0) with nowait
		declare @T table(ID int, txtCMD nvarchar(max),ExtraInfo nvarchar(max));
		while exists(select * from AzureSQLMaintenanceCMDQueue where ID>0)
		begin
			update top (1) AzureSQLMaintenanceCMDQueue set txtCMD=txtCMD output deleted.* into @T where ID>0;
			select top (1) @ID = ID, @SQLCMD = txtCMD, @ExtraInfo=ExtraInfo from @T
			raiserror(@SQLCMD,0,0) with nowait
			if @LogToTable=1 insert into AzureSQLMaintenanceLog values(@OperationTime,@SQLCMD,@ExtraInfo,sysdatetime(),null,'Started')
			begin try
				exec(@SQLCMD)	
				if @LogToTable=1 update AzureSQLMaintenanceLog set EndTime = sysdatetime(), StatusMessage = 'Succeeded' where id=SCOPE_IDENTITY()
			end try
			begin catch
				set @ScriptHasAnError=1;
				set @msg = 'FAILED : ' + CAST(ERROR_NUMBER() AS VARCHAR(50)) + ERROR_MESSAGE();
				raiserror(@msg,0,0) with nowait
				if @LogToTable=1 update AzureSQLMaintenanceLog set EndTime = sysdatetime(), StatusMessage = @msg where id=SCOPE_IDENTITY()
			end catch
			delete from AzureSQLMaintenanceCMDQueue where ID = @ID;
			delete from @T
		end
		drop table AzureSQLMaintenanceCMDQueue;
	end
	
	---------------------------------------------
	--- Clean old records from log table
	---------------------------------------------
	if @LogToTable=1
	begin
		delete from AzureSQLMaintenanceLog 
		from 
			AzureSQLMaintenanceLog L join 
			(select distinct OperationTime from AzureSQLMaintenanceLog order by OperationTime desc offset @KeepXOperationInLog rows) F
				ON L.OperationTime = F.OperationTime
		insert into AzureSQLMaintenanceLog values(@OperationTime,null,cast(@@rowcount as varchar(100))+ ' rows purged from log table because number of operations to keep is set to: ' + cast( @KeepXOperationInLog as varchar(100)),sysdatetime(),sysdatetime(),'Cleanup Log Table')
	end

	if @ScriptHasAnError=0 	raiserror('Done',0,0)
	if @LogToTable=1 insert into AzureSQLMaintenanceLog values(@OperationTime,null,null,sysdatetime(),sysdatetime(),'End of operation')
	if @ScriptHasAnError=1 	raiserror('Script has errors - please review the log.',16,1)
end
GO
print 'Execute AzureSQLMaintenance to get help' 


/*
Examples

1. run through all indexes and statistic and take smart decision about steps taken for each object
exec  AzureSQLMaintenance 'all'

1.1 add log to table
exec  AzureSQLMaintenance 'all', @LogToTable=1, @ResumableIndexRebuild=1


2. run through all indexes and statistic with no limitation (event non modified object will be rebuild or updated)
exec  AzureSQLMaintenance 'all','dummy'


3. run smart maintenance only for statistics
exec  AzureSQLMaintenance 'statistics'


4. run smart maintenance only for indexes
exec  AzureSQLMaintenance 'index'

*/