Data Compression on Andy M Mallon - AM²

I hate sp_estimate_data_compression_savings

Tue, 17 Dec 2019 10:55:26 -0500

If you’re working with compressed indexes, SQL Server provides a system stored procedure to help test the space savings of implementing data compression: sp_estimate_data_compression_savings. Starting in SQL Server 2019, it can even be used to estimate savings with columnstore.

I really don’t like sp_estimate_data_compression_savings. In fact, I kind of hate it. It’s not always very accurate–and even when it is accurate, the results can be misleading. Before I get ranty about why I don’t like it, let’s look at it in action.

Changing a column from int to bigint, without downtime

Wed, 11 Dec 2019 08:00:41 -0500

Changing a column from int to bigint has gotten a lot easier since I started working on SQL Server back at the turn of the century. SQL Server 2016 introduced the ability to do ALTER TABLE...ALTER COLUMN as an online operation using the WITH (ONLINE=ON) syntax in Enterprise Edition. This wonderful syntax now allows you to alter a column from int to bigint without causing major blocking. The int to bigint conversion is one of the most popular data type changes I see–A developer inevitably creates the table thinking they will never have more than 2 billion rows… then some years or months later 2 billion becomes a reality.

What is the row overhead when using Page Compression?

Fri, 28 Apr 2017 11:23:41 -0400

Question

I have created a table with 650 Numeric(19,4) columns. When I switch on Page Compression, by running

ALTER TABLE fct.MyTable REBUILD WITH (DATA_COMPRESSION = PAGE);

I get

Msg 1975, Level 16, State 1
Index 'PK_Mytable' row length exceeds the maximum permissible length of '8060' bytes.

T-SQL Tuesday #79 - COMPRESS()ing LOB data

Tue, 14 Jun 2016 09:00:25 -0400

It’s T-SQL Tuesday, the blog party that SQL Server expert Adam Machanic (blog|twitter) started. This month’s episode is hosted by Michael J Swart (blog| twitter). The topic: SQL Server 2016 is out!

SQL Server 2016 is hot off the presses, and Michael challenges us to blog about it.

I’ve been using SSMS 2016 (I’m impressed!), but I haven’t spent tons of time using the server-side bits. As I type this intro, the 2016 installer is chugging along getting a fresh instance ready for me to explore so I can write about…

Data Compression: How page compression works

Mon, 22 Feb 2016 10:00:59 -0500

SQL Server supports two kinds of data compression on rowstore data. Columnstore compression is for a different day. You can compress heaps, clustered indexes (on both tables and views), and nonclustered indexes (on both tables and views).

Compression requirements

Data compression is available in SQL Server 2008 & newer. It was introduced as an Enterprise Edition feature–if you were using Standard Edition or Express, then you were out of luck. Starting with SQL Server 2016 SP1 (thus all currently-supported versions), data compression is available across all Editions. There are benefits & costs to using data compression–as with anything, make sure you understand it before you implement it.

Data Compression: How row compression works

Mon, 15 Feb 2016 10:07:29 -0500

Compression requirements

Data compression is available in SQL Server 2008 & newer. It is an Enterprise Edition feature–if you’re using Standard Edition or Express, then you’re out of luck. There are benefits & costs to using data compression–as with anything, make sure you understand it before you implement it.

Data Compression: Costs & benefits

Tue, 29 Dec 2015 15:00:56 -0500

Compression requirements

Data compression is available in SQL Server 2008 & newer. It is an Enterprise Edition feature–if you’re using Standard Edition or Express, then you’re out of luck.