T-SQL Tuesday #88 – The daily (database related) WTF! The Biggest Danger to your Database: Me.

Kennie Nybo Pontoppidan ( blog | twitter ) has the honour of hosting this month’s T-SQL Tuesday and has decided to base this month’s topic on ‘The Daily (database related) WTF‘.

Now I have great time for Kennie and T-SQL Tuesday since my very first blog post was in reply to a T-SQL Tuesday and it happened to be a topic where Kennie blogged about the exact same thing!

Now, truth be told, I wasn’t planning on participating in this one and this wasn’t because of not having a WTF moment, but rather having too many of them. However, reading through most of the entries, I see a vast majority of them are about moments well in the past and caused by other parties.

This is not the case for me. My WTF moment happened recently and the culprit was … myself.

Sorry Kennie 🙁

Friday:

A request came in from our Developers about a slow performing query and my Senior DBA identifies an index that can be safely modified to improve this ones performance.
So a Maintenance Window was set and it fell to me, in my role of Junior DBA, to create a SQL Agent Job to create this index.

No worries so far right?

I create a once-off SQL Agent Job to create this index, scheduled it appropriately, and I’m off on my merry way for the weekend.

Monday:

I come in on Monday morning,  check my email, and I see an alert in my inbox about my job as well as an email from my Senior DBA; He’s not angry…WTF?

My whole job had failed!

Unable to connect to SQL Server ‘(local)’. The step failed.

He is not angry as he has seen this error message before, has dealt with it before, and sees it as a case of “well you’ve seen it now, investigate it and you won’t fall for it again”.

A quick investigation later pointed to this in the Error Log the moment before the SQL Agent Job Step was supposed to run:

[165] ODBC Error: 0, Connecting to a mirrored SQL Server instance using the MultiSubnetFailover connection option is not supported. [SQLSTATE IMH01]

Long sub-story short (i.e. Google-fu was involved), the main reason that this failed is that the SQL Agent Job Step has been configured to use a Database that is currently a mirrored one.
And SQL Agent does not like when you try to start off a step in a database that is mirrored.

So the solution for me was to set the Job Step property ‘Database’ to a non-mirrored database (preferred: [master]), then include a “USE [<mirrored database>]” in the ‘Command’ property.

Knowing what to do now, and having identified another maintenance window for the next morning, I make the required changes to the job step and continue on with my day.

Tuesday:

I come in on Tuesday morning,  check my email, and I see an alert in my inbox about my job as well as an email from my Senior DBA; He’s angry…WTF?

My final job step had failed!

CREATE INDEX failed because the following SET options have incorrect settings: ‘QUOTED_IDENTIFIER’. Verify that SET options are correct for use with indexed views and/or indexes on computed columns and/or filtered indexes and/or query notifications and/or XML data type methods and/or spatial index operations. [SQLSTATE 42000] (Error 1934).  The step failed

Now I’m angry too since I count these failures as personal and I don’t like failing, so I get cracking on the investigation.
Straight away, that error message doesn’t help my mood.
I’m not indexing a view!
I’m not including computed columns!
It’s not a filtered index!
The columns are not xml data types, or spatial operations!
And nowhere, nowhere am I using double quotes to justify needing to set QUOTED_IDENTIFIER on!

SO WTF SQL SERVER, WHY ARE YOU GIVING ME THESE ERRORS???

SET QUOTED_IDENTIFIER must be ON when you are creating or changing indexes on computed columns or indexed views. If SET QUOTED_IDENTIFIER is OFF, CREATE, UPDATE, INSERT, and DELETE statements on tables with indexes on computed columns or indexed views will fail.

I’ve talked about stupid error message before… but in my current mood I wail, beat my breast, and stamp my feet!
The error message above was not complaining about the index I was creating, it was complaining about indexes already on the table!
In my case, we had filtered indexes already created on the table and, as such, every single index on this table from then on requires SET QUOTED_IDENTIFIER ON.

USE [TEST];
SET QUOTED_IDENTIFIER ON;

CREATE ...

Third Time’s the Charm?

No, not this time.

Luckily the Senior DBA had come in while the maintenance window was still running and manually ran the create index script.

He wasn’t angry that my job step failed. He was angry that my first job step succeeded!

Are you going “WTF? Why is he angry about that?” Let me enlighten you…

Remember at the start of this blog post I said that he had identified an index that could be safely modified?
Well, on Monday, in my haste to fix my broken job I had focused too much and thought too granular.
My second job step that created the index had failed, but my first job step, the one that dropped the original index had succeeded.

There’s not really much more to say on this. In my rush to fix a broken job, I created a stupid scenario that was luckily caught by the Senior DBA.

Wrap Up:

Yeah…so thought it would be a nice, little counter-example to the other posts out there about third parties coming along and wrecking havoc, and the DBAs swooping in to save the day.

I could make up excuses and say that, as a Junior DBA, I’m expected to make mistakes but I’m not going to.

It should be the aspiration of every Junior DBA to strive to improve and move upwards, and one of the key aspects of this is responsibility.

You should be responsible for looking after the data, looking after the jobs, and looking after the business.
And if all else fails, you should be responsible for your actions.

I have been properly chastised by my Senior and am still chastising myself for this. It’s been a long week so far…

… and it’s only Tuesday…wtf?