Why is fn_xe_file_target_read_file the worst SQL function?
A rant about fn_xe_file_target_read_file - the nvarchar(max) return type, broken time filtering, and the circular dependency for finding rollover files.
Extended Events
16 posts
Extended Events and I (T-SQL Tuesday #166)
Grant Fritchey asked us to talk about our favourite SQL Server tool for T-SQL Tuesday #166. Mine is Extended Events - and I have the GitHub repo and a public speaking session to prove it.
Default event_file path for Extended Events
Create an Extended Events session with just a filename and the .xel file lands somewhere - but where? Here's what the default path is and how to change it.
What's in a name? (T-SQL Tuesday #152)
My T-SQL Tuesday rant: an app that connects as '.Net SqlClient Data Provider' turns debugging into a manhunt. Please, name your apps.
Scary Scalar Functions - Part Two: Performance
A Scalar function that does literally nothing still runs over 20 times slower. Here is the proof, measured four different ways.
What is causing my constraint to be untrusted?
You fix an untrusted constraint, and by morning it's back to untrusted. Here's how to catch the process responsible, using Extended Events.
New Extended Events in SQL Server 2022
SQL Server 2022's CTP has dropped. I diffed its Extended Events against 2019 and pulled out the few new ones worth a look.
Query Hash and Query Plan Hash Mapping
Ever struggled to match the binary hash from DMVs and Query Store against the numeric one in Extended Events? Let's fix that for good.
KEEP PLAN Demystified
Ever wondered what the KEEP PLAN hint actually does? The docs are vague, so I tested it against every recompilation threshold to find out.
Extended Events Timezones
Open an XE event file in SSMS and the timestamps stare back at you. Local time or server time? I spun up a container in another timezone to find out.
How to audit data modifications with surgical precision
A colleague needed to find who was changing a specific cell in a busy table. SQL Audit was too noisy, Query Store too vague. I found a way to combine triggers with Extended Events for surgical precision.
IS Lock in RCSI Enabled Database
I found an IS lock in a deadlock report on an RCSI database. That shouldn't be possible. Here's what caused it.
Query Store default settings
Query Store comes with default settings - but are they what the documentation says? Let's find out using a simple Extended Events session.
Investigating Errors With Extended Events
Production errors are hard to reproduce. Here's my go-to Extended Events session that captures errors with their full TSQL calling stack.