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Day: November 23, 2016

Building Custom Containers

Published 2016-11-23 by Kevin Feasel

Andrew Pruski grabs the vNext Docker image and creates a new container and image with his modifications:

Once the command has executed you can connect remotely via SSMS using the server name and the port we specified above. The database that we created in the original image will be there, along with the data that we entered!

This is where containers start to come into their own in my opinion. You can build your own custom images and quickly spin up multiple instances that already have all the databases that you require!

Containerizing databases is something I haven’t quite got my head wrapped around yet (because we want to maintain that state over time, even if the image gets deleted), so I’m interested in seeing where this series goes.

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Locks In Sp_configure

Published 2016-11-23 by Kevin Feasel

Kendra Little discusses the locks entry in sp_configure:

Each lock uses 96 bytes of memory. On the instance in question, 25,000 locks  = 2,400,000 bytes.

That’s only 2.3 MB of memory devoted to locks. Even though 25K  sounds like a lot, the memory footprint for that is pretty darn small.

I checked back with our questioner, and their instance has 32GB of memory. That’s a pretty small amount in the grand scheme of things (as of SQL Server 2014, Standard Edition can use up to 128GB of memory for the Buffer Pool), but 2.3 MB isn’t anything to worry about, percentage wise.

Read on for advice if you’re seeing your SQL Server instance take a very large number of locks.

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SQL Server On Linux Is Boring

Published 2016-11-23 by Kevin Feasel

Grant Fritchey, defying the common opinion (or is he?):

Suddenly though, it was boring. I tested a few Redgate tools (SQL Compare is right there above, connected to Linux) to be sure they worked. No major issues encountered. Great. However, now, it’s just another instance of SQL Server.

I guess I could start complaining that SQL Agent isn’t there… except I’m not that big a fan of SQL Agent, and I can schedule all sorts of stuff to run in Linux using the sqlcmd command line tool.

This is a good kind of boring.

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Preventing DBCC DBREINDEX?

Published 2016-11-23 by Kevin Feasel

Dave Mason is looking for a way to prevent a user from running DBCC REINDEX:

After a little digging, I discovered the related database user is a member of the db_ddladmin fixed database role. Members of that role are permitted to run DBCC REINDEX. Since I have existing (more sensible) code in place for index maintenance, I don’t want the DBCC REINDEX operations to continue. Here’s the problem: I can’t find a direct way to DENY a database user from running DBCC commands. T-SQL syntax doesn’t support something like DENY DBCC TO <user> or DENY DBCC REINDEX TO <user>. MSDN documentation tells me the equivalent ALTER INDEX command requires at minimum ALTER permission on the table or view. I guessed that revoking or denying ALTER TABLE privileges might prevent a user from executing DBCC DBREINDEX, but that does not appear to be the case.

That’s painful.

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Buffer Pool TreeMap

Published 2016-11-23 by Kevin Feasel

Aaron Nelson has a post on using Powershell to visualize contents in the buffer pool:

On Monday Chrissy LeMaire & I Did a session called “SQL Server Cmdlets and Community Involvement” for the PowerShell 10 Year Anniversary all-day event on Channel9 on MSDN. If you jump to the 18 minutes 30 second mark of that video you’ll see me showing how to look at the Buffer Pool of your SQL Server instance, first with the Out-GridView cmdlet, then I used a function from PowerShell MVP Boe Prox ( b | t ) called Out-SquarifiedTreeMap like so:

Read on to get a link to the code.

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Upcoming Polybase Enhancements

Published 2016-11-23 by Kevin Feasel

James Serra knows how to get my interest:

Polybase was first made available in Analytics Platform System in March 2013, and then in SQL Server 2016.  The announcement at the PASS Summit was that by preview early next year, in addition to Hadoop and Azure blob storage, PolyBase will support Teradata, Oracle, SQL Server, and MongoDB in SQL Server 2016.  And the Azure Data Lake Store will be supported in Azure SQL Data Warehouse PolyBase.

With SQL Server 2016, you can create a cluster of SQL Server instances to process large data sets from external data sources in a scale-out fashion for better query performance (see PolyBase scale-out groups):

I’m excited for the future of Polybase and looking forward to vNext and vNext + 1 (for the stuff which they can’t possibly get done in time for vNext).

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Timeline Visual

Published 2016-11-23 by Kevin Feasel

Devin Knight looks at a new Power BI custom visual:

  • The Timeline is similar to the native slicer in Power BI but has several more customizations available.

  • Not surprising, this visual can only accept date values.

  • If you need to adjust the start date of the Timeline based on your works Fiscal Calendar that is possible in the format settings.

This is a pretty nice visual, but when I tried to use it, I remember it feeling a little limiting, particularly around drilling into date slices.

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STRING_SPLIT Results

Published 2016-11-23 by Kevin Feasel

Louis Davidson looks at a couple edge cases with the STRING_SPLIT function in SQL Server 2016:

But what about the two versions of an empty value? ” (zero-length/empty string) and NULL. My NULL sense told me that the NULL one would return a single row with NULL, and the empty string would return a single empty string row.  Of course, I was wrong, and it makes sense why (a row of NULL would be really annoying, especially if you want to use the output as an exclusion list, because A NOT IN (SET(B,NULL)) always returns NULL, not TRUE. )

For example, say the output could include NULL. You could end up with something like the following, where even though the input value of A is not in the NOT IN list, no rows are returned:

Click through for more details.

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