SQL Server

The free SQL Server 2019 preview download is out, and here are quite a few things to check out that aren’t documented yet: New System Objects Starting with new stored procedures: sys.sp_add_feature_restriction sys.sp_autoindex_cancel_dta sys.sp_autoindex_invoke_dta sys.sp_cloud_update_blob_tier sys.sp_configure_automatic_tuning sys.sp_diagnostic_showplan_log_dbid sys.sp_drop_feature_restriction sys.sp_execute_remote sys.sp_force_slog_truncation sys.sp_internal_alter_nt_job_limits sys.sp_rbpex_exec_cmd sys.sp_set_distributed_query_context sys.sp_set_session_resource_group sys.sp_showinitialmemo_xml sys.sp_xa_commit sys.sp_xa_end sys.sp_xa_forget sys.sp_xa_forget_ex sys.sp_xa_init sys.sp_xa_init_ex sys.sp_xa_prepare sys.sp_xa_prepare_ex sys.sp_xa_recover sys.sp_xa_rollback…

What’s New in SQL Server 2019’s sys.messages: More Unannounced Features

September 24, 2018

The system table sys.messages holds error messages that SQL Server needs to return to end users. When a new build comes out, I love checking this table to see what features Microsoft has coded, but isn’t quite ready to announce yet. When SQL Server 2017 came out, that’s how I unmasked snapshot materialized views, a…

What’s New in SQL Server 2019: Faster Table Variables (And New Parameter Sniffing Issues)

September 24, 2018

SQL Server 2019, T-SQL

For over a decade, SQL Server’s handling of table variables has been legendarily bad. I’ve long used this Stack Overflow query from Sam Saffron to illustrate terrible cardinality estimation: Transact-SQL declare @VoteStats table (PostId int, up int, down int) insert @VoteStats select PostId, up = sum(case when VoteTypeId = 2 then 1 else 0 end), down…

What’s New in SQL Server 2019: Adaptive Memory Grants

September 24, 2018

Execution Plans, SQL Server 2019

When you run a query, SQL Server guesses how much memory you’re going to need for things like sorts and joins. As your query starts, it gets an allocation of workspace memory, then starts work. Sometimes SQL Server underestimates the work you’re about to do, and doesn’t grant you enough memory. Say you’re working with…

Leaked: SQL Server 2019 Big Data Clusters Introduction Video

September 22, 2018

Psst – you’re probably not supposed to see this yet, but look what @WalkingCat found: SQL Server 2019 Vision pic.twitter.com/zbjI28FYSu — WalkingCat (@h0x0d) September 21, 2018 What the video says Growing volumes of data create deep pools of opportunity for those who can navigate it. SQL Server 2019 helps you stay ahead of the changing time…

A Simple Stored Procedure Pattern To Avoid

September 19, 2018

Execution Plans, SQL Server

Get Yourself Together This is one of the most common patterns that I see in stored procedures. I’m going to simplify things a bit, but hopefully you’ll get enough to identify it when you’re looking at your own code. Here’s the stored procedure: Transact-SQL CREATE OR ALTER PROCEDURE dbo.you_are_not_clever ( @cd DATETIME NULL) AS BEGIN…

Quirks When Working With Extended Events To Track Locks

September 13, 2018

Worse Than Mobile Browsing I have a love/hate relationship with Extended Events. Yes, they’re powerful. Yes, you can track interesting things. But they’re just not intuitive, like, 10 years on. Part of the problem is that the narrative from Microsoft has been that it’s a full replacement for Profiler and Traces. How many monitoring tool…

Can Forced Parameterization Go Wrong?

September 11, 2018

Execution Plans, SQL Server

App Like That If you’ve got the kind of application that sends bare-assed strings to SQL Server, you may end up with a weird choice. Brent will be sitting on one shoulder telling you to use Forced Parameterization. I’ll be on the other shoulder asking if you’ve really thought this whole thing through while you…

Announcing SQL Server 2019

September 8, 2018

TEASE Who Let The Docs Out? Ignite must be coming up. If you head over to Microsoft’s GitHub repo, you can peruse around for stuff updated recently. Maybe you’ll create an account. Maybe you’ll start contributing to open source projects. Maybe you’ll quietly slip into a world of solitude for days on end. Happy Saturday!…

Locks Taken During Indexed View Modifications

September 5, 2018

Locking, Blocking, and Isolation Levels, SQL Server

Frankenblog This post has been nagging at me for a while, because I had seen it hinted about in several other places, but never written about beyond passing comments. A long while back, Conor Cunningham wrote: This same condition applies to indexed view maintenance, but I’ll save that for another day :). AFAIK he hasn’t…

Foundational Material: Microsoft SQL Server Book and Blogs From The Past

August 21, 2018

What Did Dinosaurs Watch On TV? These are some of my favorite books and blogs from Microsoft from the way-back machine. I can’t say every bit of information is still 100% true and should be followed to the letter, but hey, that’s what happens. This is stuff I consider foundational material, though. I’ve learned a…

Wait Stats When VSS Snaps Are Slow

August 16, 2018

Deus Redux A while back I wrote about the Perils of VSS Snaps. After working with several more clients having similar issues, I decided it was time to look at things again. This time, I wanted blood. I wanted to simulate a slow VSS Snap and see what kind of waits stats I’d have to…

How Trace Flag 2335 Affects Memory Grants

August 15, 2018

This trace flag is documented in KB #2413549, which says, “Using large amounts of memory can result in an inefficient plan in SQL Server.” The details are a little light, so let’s run a quick experiment with: SQL Server 2017 CU 8 (14.0.3029.16) VM with 4 cores, 32GB RAM, max memory set to 28GB Stack Overflow…

A Common Query Error

August 14, 2018

So Many Choices When you only need stuff from a table where there’s matching (or not!) data in another table, the humble query writer has many choices. Joins In/Not In Exists/Not Exists No, this isn’t about how NOT IN breaks down in the presence of NULLs, nor is it a performance comparison of the possibilities.…

Setting Up SQL Server: People Still Need Help

August 13, 2018

Brent Ozar Unlimited Team

I Like What’s Happening I wanna start off by saying that I like what Microsoft has been doing with the setup process — it made a lot of sense to add the tempdb configuration screen, and having a checkbox to turn on Instant File Initialization was amazingly helpful. Even in the cloud, people still need…

[Video] Office Hours 2018/8/1 (With Transcriptions)

August 5, 2018

SQL Server, Videos

No Comments

This week, Erik and Richie discuss monitoring tools, finding all unused tables across databases, query tuning, deleting vs hanging on to indexes, sharding databases, query editors, aggressively-locked indexes, why a plan would not be in the plan cache, and Richie’s current housing situation. Here’s the video on YouTube: You can register to attend next week’s Office Hours,…

Do I Have A Query Problem Or An Index Problem?

July 26, 2018

Party Up When someone says “this query is slow”, and you can rule out contextual stuff like blocking, odd server load, or just an underpowered server, what’s the first thing you look at? There’s a lot of potential culprits, and they could be hiding in lots of different places. Pick a card, any card. After…

CXCONSUMER Is Harmless? Not So Fast, Tiger.

July 24, 2018

Execution Plans, SQL Server

In Theory Let’s say you’ve got a query, and the point of that query is to take your largest customer/user/whatever and compare their activity to smaller whatevers. You may also stumble upon this issue accidentally if your query happens to capture populations like that by accident. For our purposes, let’s look at a query that…

A New tempdb Trace Flag Appears!

July 17, 2018