1. Nifty trick to compress LOB data
Phil Grayson Aireforge.com

2. Phil Grayson @databoffin
Consultant at xTEN
Chief ticket creator at Aireforge
Organizer of Data n’ Gravy & Leeds Data Platform UG
Friend of Redgate, SQLBits
Blogs: philgrayson.me, blog.aireforge.com, blog.xten.uk
19 years of SQL Server experience (7.0 to 2019)

3. Data compression options
Row Compression
Page Compression
Columnstore
Columnstore Archival

4. COMPRESS() & UNCOMPRESS()
To Compress
COMPRESS('String here');
Returns varbinary(max)
To Decompress
CAST(DECOMPRESS('String here') AS VARCHAR(512)) AS Text;
Note: For SQL Server 2016 use a GZIP CLR function
Supported Datatypes
binary(n)
char(n)
nchar(n)
nvarchar(max)
nvarchar(n)
varbinary(max)
varbinary(n)
varchar(max)
varchar(n)

5. SELECT TOP(10) * FROM dbo.Requests

6. Check the sizes Max row length Max row length (after compression)
SELECT MAX(LEN(Payload))
FROM dbo.Requests;
--8,000
Max row length (after compression)
SELECT MAX(LEN(COMPRESS(Payload)))
FROM dbo.Requests;
--1,375 (82.8%)
NOTE: This allows for VARBINARY(2000)

7. SELECT TOP(10) * FROM dbo.Requests

8. Computed columns

9. Computed columns CREATE TABLE [dbo].[Requests_Compress] (
[RequestID] [INT] IDENTITY(1, 1) PRIMARY KEY CLUSTERED NOT NULL,
[Payload] AS (CONVERT([VARCHAR](MAX), DECOMPRESS([Payload_Compressed]), (0))),
[Payload_Compressed] [VARBINARY](2000) NOT NULL );
INSERT INTO [dbo].[Requests_Compress] (Payload_Compressed)
SELECT CONVERT(VARBINARY(2000), COMPRESS(Payload)) AS Payload_Compressed
FROM dbo.Requests;

10. Comparing compression
4015GB
Uncompressed Data
721MB
Compress
-82% Reduction
680MB
Compress + Page
-83% Reduction
-5.7% Extra
668MB
Compress + Row
-7.3% Extra

11. Things to remember Requires a code change
Compressed data & computed columns can’t be indexed
INSERT, UPDATE & DELETE overhead
Durable computed columns will consume more space

12. And that’s it. Any questions?
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