CREATE TABLE [dbo].[Temperatures](
	[DateAndTime] [datetime2](7) NULL,
	[TagIndex] [smallint] NULL,
	[Val] [float] NULL
) ON [PRIMARY]

CREATE NONCLUSTERED INDEX [TemperaturesIndex] ON [dbo].[Temperatures]
(
	[DateAndTime] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]

declare @from datetime2 = '2020-03-02 00:00:00.0000000';
declare @till datetime2 = '2020-03-02 01:00:00.0000000';
SELECT avg([Val])
  FROM [dbo].[Temperatures]
  WHERE ([TagIndex] = 198) 
    AND ([DateAndTime] >= @from)
    AND ([DateAndTime] < @till)

 with (index = [TemperaturesIndex])

with (index = [TemperaturesIndex])

CREATE NONCLUSTERED COLUMNSTORE INDEX [имя] ON [dbo].[Temperatures]
(
	[DateAndTime],  -- ??
	[TagIndex],  -- ??
	[Val]  -- ??
)

create index [имя] on [dbo].[Temperatures] (TagIndex, DateAndTime) include (Val);

create clustered index [имя] on [dbo].[Temperatures] (TagIndex, DateAndTime);

CREATE NONCLUSTERED COLUMNSTORE INDEX [имя] ON [dbo].[Temperatures] (TagIndex, DateAndTime, Val);

CREATE TABLE [dbo].[Temperatures_FloatTable](
	[DateAndTime] [datetime2](7) NULL,
	[Millitm] [smallint] NULL,
	[TagIndex] [smallint] NULL,
	[Val] [float] NULL,
	[Status] [nvarchar](1) NULL,
	[Marker] [nvarchar](1) NULL
) ON [PRIMARY]
GO

CREATE NONCLUSTERED COLUMNSTORE INDEX [Temperatures_FloatTable_CSI_TagDT] ON [dbo].[Temperatures_FloatTable] (TagIndex, DateAndTime, Val);

with (index = [Temperatures_FloatTable_CSI_TagDT]

create index [имя] on [dbo].[Temperatures] (TagIndex, DateAndTime) include (Val);