A couple of week ago I kicked off a survey about common causes of performance problems – see here for the survey. Firstly I asked what was the root cause for the most recent performance problems you looked at – here are the results: Secondly I asked what you think the overall most common [...]
Paul S. Randal
In Recovery...
Survey results: Common causes of performance problems
Posted on: April 6, 2011 6:37 am
Query plan analysis first steps
Posted on: March 16, 2011 2:28 pm
About a month ago I kicked off a survey asking what you look for when first analyzing a plan for a poorly performing query. You can see the original survey here. Here are the survey results: The "Other" values are as follows: 13 x "Most expensive as percentage of total cost of batch" 7 [...]
Survey: what’s your plan for a plan?
Posted on: February 6, 2011 10:00 am
In my survey for this week I'm interested in what you look for first when analyzing a query plan. I'll report on the results around mid-February. Thanks! PS Post comments are disabled to avoid skewing the results.
Two great blog series on joins and query plan operators
Posted on: January 29, 2011 8:10 am
I was doing some research this morning for some query tuning on a client system and I came across a couple of blog series with some excellent posts for those looking to learn more about query plans (and as a handy reference). The first series is by Craig Freedman on the Query Processor team at [...]
Adventures in query tuning: non-seekable WHERE clause expressions
Posted on: January 16, 2011 1:07 pm
I've been doing a lot of performance tuning work over the last couple of months and this weekend found something that's very pervasive out in the wild. Kimberly was helping me optimize a gnarly query plan and spotted something in the code I hadn't noticed that was causing an index scan instead of an index [...]
Adventures in query tuning: unexpected key lookups
Posted on: May 1, 2010 6:26 pm
I'm starting a new blog category to talk about some of weird and confusing stuff I see while query tuning. First up is the case of the unexpected Key Lookup (Clustered) in a query that looks like it should be covered. This is a follow on from the post Missing index DMVs bug that could [...]
Missing index DMVs bug that could cost your sanity…
Posted on: May 1, 2010 4:41 pm
Here's yet another reason to be very careful when using the missing index DMVs… There's a bug in the missing index DMVs that could end up causing you to knock your head against a brick wall and question your sanity. I know I did. The bug is this: the missing index code may recommend a nonclustered [...]
