sql-server-samples/samples/features/unicode/notebooks/Storage.ipynb

Storage savings in UTF-8 vs UTF-16

In [1]:

USE master;
DROP DATABASE IF EXISTS LatinDatabase;
CREATE DATABASE LatinDatabase COLLATE LATIN1_GENERAL_100_CI_AS_SC_UTF8
GO

USE LatinDatabase
GO
DROP TABLE IF EXISTS MyTable;
CREATE TABLE MyTable (c1 NCHAR(10), c2 CHAR(10))
GO

INSERT INTO MyTable (c1, c2)
VALUES ('UTF16','UTF8')
GO

SELECT DATALENGTH(c1) AS [UTF16_Col], DATALENGTH(c2) AS [UTF8_Col]
FROM MyTable
GO

Out [1]:

Commands completed successfully.

Commands completed successfully.

Commands completed successfully.

(1 row affected)

(1 row affected)

Total execution time: 00:00:00.397

UTF16_Col	UTF8_Col
20	10

Insert 1M Rows Latin

Setup tables

In [2]:

USE LatinDatabase
GO
DROP TABLE IF EXISTS dbo.Inserts_UTF16
CREATE TABLE dbo.Inserts_UTF16(
    ID int IDENTITY(1,1) NOT NULL PRIMARY KEY
    , col1 NVARCHAR(50) NOT NULL)
GO
DROP TABLE IF EXISTS dbo.Inserts_UTF8
CREATE TABLE dbo.Inserts_UTF8(
    ID int IDENTITY(1,1) NOT NULL PRIMARY KEY
    , col1 VARCHAR(50) NOT NULL)
GO

Commands completed successfully.

Commands completed successfully.

Commands completed successfully.

Total execution time: 00:00:00.047

Insert same data set to all tables

In [5]:

-- UTF16
SET NOCOUNT ON;
BEGIN TRAN
DECLARE @i int = 1
WHILE @i < 1000000
BEGIN
    INSERT INTO dbo.Inserts_UTF16 (col1) 
	SELECT REPLICATE(CONCAT(
	  CHAR(FLOOR(65 + (RAND() * 25))),
	  CHAR(FLOOR(65 + (RAND() * 25))),
	  CHAR(FLOOR(65 + (RAND() * 25))),
	  CHAR(FLOOR(65 + (RAND() * 25))),
	  CHAR(FLOOR(65 + (RAND() * 25))),
	  CHAR(FLOOR(65 + (RAND() * 25))),
	  CHAR(FLOOR(65 + (RAND() * 25))),
	  CHAR(FLOOR(65 + (RAND() * 25))),
	  CHAR(FLOOR(65 + (RAND() * 25))),
	  CHAR(FLOOR(65 + (RAND() * 25)))
	  ), 5);
    SET @i += 1
END;
COMMIT
GO

Commands completed successfully.

Total execution time: 00:00:20.006

In [6]:

-- UTF8
SET NOCOUNT ON;
BEGIN TRAN
DECLARE @i int = 1
INSERT INTO dbo.Inserts_UTF8 (col1) 
SELECT col1 FROM dbo.Inserts_UTF16;
COMMIT
GO

Commands completed successfully.

Total execution time: 00:00:16.114

Check data record sizes

Note data lenght sizes are the same whether compressed or not

In [9]:

SELECT TOP 1 DATALENGTH(col1) AS [DataLength_UTF16]
FROM Inserts_UTF16
GO
SELECT TOP 1 DATALENGTH(col1) AS [DataLength_UTF8]
FROM Inserts_UTF8
GO

Out [9]:

Commands completed successfully.

Commands completed successfully.

Total execution time: 00:00:00.012

DataLength_UTF16
100

DataLength_UTF8
50

Check table sizes

In [10]:

SELECT OBJECT_NAME(p.OBJECT_ID) AS TableName,
	p.ROWS AS NumRows, a.used_pages, a.total_pages,
	CONVERT(DECIMAL(19,2),ISNULL(a.used_pages,0))*8/1024 AS DataSizeMB
FROM sys.allocation_units a
INNER JOIN sys.partitions p ON p.hobt_id = a.container_id
	AND OBJECT_NAME(p.OBJECT_ID) LIKE 'Inserts%'
ORDER BY TableName
GO

Out [10]:

Commands completed successfully.

Total execution time: 00:00:00.438

TableName	NumRows	used_pages	total_pages	DataSizeMB
Inserts_UTF16	2999997	43642	43649	340.9531250
Inserts_UTF8	3999996	33459	33489	261.3984375