Dear SQL DBA

If you need to add, remove, or replace hints from ad-hoc queries and you can't change the code, plan guides can help. See a demo of removing hints from parameterized TSQL run from an application, and get tips on how to make your plan guides work in SQL Server.

Get code samples from this episode here: https://sqlworkbooks.com/2017/05/removing-query-hints-with-plan-guides-dear-sql-dba-episode-43/

Learn what batch mode is in SQL Server, and how you can trick SQL Server into using it (even without a "real" columnstore index).

For clickable links and demo code, head to https://sqlworkbooks.com/2017/05/batch-mode-hacks-for-rowstore-queries-in-sql-server/

Find out if getting certified will help you land an entry level DBA job, and if you do want to get certified, get Kendra's tips on preparing for the exam.

Ever had a database change go horribly wrong? It can feel awful in the moment, then eat away at your confidence for days afterward. In this 20 minute episode Kendra gives you practical steps that help you cope with change over the course of your DBA career.

An important query is suddenly slow. Is it because statistics are out of date? This is tricky to figure out, and updating statistics right away can make troubleshooting even harder. Learn how to use query execution plans to get to the heart of the question and find out if stats are really your problem, or if it's something else. In this 35 minute episode:

00:39 SQL Server 2017 Announced 01:10 New video from Microsoft's Joe Sack demonstrating Adaptive Query Processing 03:05 This week's question: Are bad stats making my query slow? 05:26 Demo of finding plan in cache and analyzing stats begins 28:17 What to do when stats ARE the problem

Code samples: https://gist.github.com/LitKnd/f07848d59cedc61fd057d12ab966f703

Links from the episode:

SQL Server 2017 Adaptive Query Processing video by Joe Sack: https://www.youtube.com/watch?v=szTmo6rTUjM&feature=youtu.be

Michael J Swart on finding Dark Matter Queries: http://michaeljswart.com/2017/04/finding-your-dark-queries/

Got a question for Dear SQL DBA? https://SQLWorkbooks.com/ask

They made their index maintenance job smarter, and their queries got slower in production afterward. Could the index maintenance have harmed performance? In this episode... 00:50 Thinking about plan freezing in Query Store and multi-team process 03:15 This week's question about index maintenance and query performance

The dev server got bogged down during a deployment and lock timeouts were everywhere. Was the perfmon counter way off about how much memory was being used just for locks? In this episode...

00:33 What's new @ SQL Workbooks: Down the Rabbit Hole 03:00 This week's question about lock timeouts & memory in SQL Server

A database transaction log is expanding, even though the DBA is running log backups and doesn't see an open transaction? What's going on with this Availability Group?

Timestamps in this episode if you want to skip ahead:

00:49 What's new @ SQL Workbooks 03:22 Info on SQLPASS Summit Content Survey & a heads-up for aspiring precon speakers 05:35 This week's question about t-log growth

A few episodes ago, I talked about how learning about Write Ahead Logging was a light bulb moment for me, and helped me learn tons of concepts about backups and recovery. This week, we talk about when SQL Server turns things upside down and doesn't use write ahead logging: and what it has to do for recovery in these special cases.

When you migrate a database, it can be useful to prove that you moved all the data and didn't miss any transactions. Learn how to use a tail log backup in a migration scenario.