Confused by sp_who2 (Dear SQL DBA Episode 30)
This week’s ‘Dear SQL DBA’ question gets us down to the essentials: how to I tell if a transaction is hanging?
The Top 3 Mistakes I Made Fighting Blocking
At the beginning of the “Troubleshooting Blocking and Deadlocks” course, I mention that it took me a long time to get into using the tools I show in the course.
The tools are all free, and many of them are built into SQL Server.
Update: the course itself is now free, too!
New online course: Troubleshooting Blocking & Deadlocks for Beginners (Free!)
I made y’all a SQL Server style Valentine’s day present: a new FREE online training course.
Should I Learn Fulltext Indexing? (Dear SQL DBA Episode 29)
This week’s question is about a longstanding feature in SQL Server that sounds really cool: full-text search. If you’re learning performance tuning, how much time should you invest in researching and learning about full-text indexes?
Understanding Left vs. Right Partition Functions (with Diagrams)
You’re designing table partitioning, or you want to make a change to an existing partition function. It’s critical to understand the difference between how “left” and “right” partition functions behave, but the documentation is a bit confusing on this topic.
Index Types: Heaps, Primary Keys, Clustered and Nonclustered Indexes (Dear SQL DBA Episode 28)
I see HEAP tables are found even when I know those tables have a clustered index, and I see a lot of forwarded records. This happens to 5 tables in my database. I can see the clustered and in some ones the non-clustered indexes… why are some scripts reporting them as heaps?
Which Filegroup is that Partition Using? How Many Rows Does It Have?
Table Partitioning in SQL Server has a bit of a learning curve. It’s tricky to just figure out how much data you have and where the data is stored.
What is that Garbage in my Execution Plan? (Dear SQL DBA Episode 27)
Today I was working on some code samples for a user question, and I hit a weird roadblock.
There was a bunch of garbage in my execution plan that I couldn’t explain. And by ‘garbage’, I mean a nested loop to a whole branch of code that I hadn’t asked SQL Server to run – and a warning about an implicit conversion possibly causing problems with the quality of my execution plan.
How to Find Queries Using an Index (and Queries Using Index Hints)
Sometimes you know a query is out there, but it’s hard to find the exact query.
SQL Server stores query execution plans in cache, but it can be difficult to query the XML it stores. And there’s always a chance that the query plan won’t be there, due to memory pressure, recompile hints, or the plan cache being cleared by setting changes or other administrative actions.
Why You Should Switch in Staging Tables Instead of Renaming Them (Dear SQL DBA Episode 26)
Over the years, I’ve come across a pattern fairly frequently: an application in an OLTP database periodically creates new tables, loads some data into them and fixes it up, then does a switcheroo and replaces old tables with the new tables.
This can cause major problems with blocking if anyone else is querying the table.