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sys.sp_estimated_rowsize_reduction_for_vardecimal

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Syntax
create procedure sys.sp_estimated_rowsize_reduction_for_vardecimal
	@table_name nvarchar (776)
as
begin
	set nocount on

	-- Get the table ID.
	declare @table_id int;
	set @table_id = object_id(@table_name);

	-- If we can't find an object with this name, or if it's not a user table, or if
	-- it doesn't belong to this database, give up.
	if (@table_id is null
		or objectproperty(@table_id, 'IsUserTable') = 0
		or not exists (select * from sys.tables where object_id = @table_id))
	begin
		raiserror(15388, -1, -1, @table_name);
		return @@error;
	end;

	-- Get physical stats for the table.
	create table #physical_stats(alloc_unit_type_desc nvarchar(60), record_count bigint, avg_record_size_in_bytes float);
	insert into #physical_stats select alloc_unit_type_desc, record_count, avg_record_size_in_bytes from
		sys.dm_db_index_physical_stats(db_id(), @table_id, objectproperty(@table_id, 'TableHasClustIndex'), 0, 'SAMPLED');

	-- Get the table's size.
	declare @table_size float;
	select @table_size = sum(avg_record_size_in_bytes * record_count) from #physical_stats;

	-- Get the row count.
	declare @row_count bigint;
	select @row_count = sum(record_count) from #physical_stats where alloc_unit_type_desc = 'IN_ROW_DATA';

	-- Now estimate the average savings per row.
	declare @avg_savings float;
	exec sys.sp_decimal_estimate_savings_for_table @table_id, @avg_savings output;

	declare @avg_rowlen_fixed_format float, @avg_rowlen_vardecimal_format float;
	if (@row_count > 0)
	begin
		-- Get the average row size.
		declare @avg_row_size float;
		set @avg_row_size = @table_size / @row_count;

		-- If the table is not compressed, subtract the savings from the actual size to get the
		-- compressed size. If the table is already compressed, add the savings to the actual
		-- size to get the uncompressed size.
		if (objectproperty(@table_id, 'tablehasvardecimalstorageformat') = 0)
			select @avg_rowlen_fixed_format = @avg_row_size, @avg_rowlen_vardecimal_format = @avg_row_size - @avg_savings;
		else
			select @avg_rowlen_fixed_format = @avg_row_size + @avg_savings, @avg_rowlen_vardecimal_format = @avg_row_size;
	end
	else
	begin
		select @avg_rowlen_fixed_format = 0, @avg_rowlen_vardecimal_format = 0;
	end;
	
	-- Select the result set.
	select cast(@avg_rowlen_fixed_format as decimal(12, 2)) as avg_rowlen_fixed_format,
		cast(@avg_rowlen_vardecimal_format as decimal(12, 2)) as avg_rowlen_vardecimal_format,
		@row_count as row_count;
end;

 
Last revision 2008RTM
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