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Month: March 2016

Index Cannot Be Reorganized

Published 2016-03-21 by Kevin Feasel

Jason Brimhall digs into an error where page-level locking is disabled:

You receive the error message similar to the following:

Msg 2552, Level 16, State 1, Line 1 The index “blah” (partition 1) on table “blah_blah_blah” cannot be reorganized because page level locking is disabled

Immediately, you start double-checking yourself and verifying that it worked the previous night. You even go so far as to confirm that the same index was previously reorganized. How is it possible that it is failing now on this index. What has changed? Has something changed?

There’s an interesting troubleshooting story, but the important message is about setting up a good set of Extended Events so that you can troubleshoot these types of problems.

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SSAS Tabular In DirectQuery Mode

Published 2016-03-21 by Kevin Feasel

Melissa Coates digs into DirectQuery mode on Tabular models:

When developing an SSAS Tabular model, you can choose one of two options for handling the underlying data:

In-Memory Mode (aka Imported Mode).  Stores the data in the in-memory model, so all queries are satisfied by the data imported into the Tabular model’s storage engine. This requires the model to be processed for updated data to become available for reporting. This mode is conceptually analogous to MOLAP in SSAS multidimensional models (though the SSAS architecture differs significantly).

DirectQuery Mode. Leaves the data in the source and sends the queries to the underlying database. In this case there’s no processing and SSAS serves as a semantic model to improve the user experience. This mode is conceptually analogous to ROLAP in SSAS multidimensional models (though there are architectural / implementation differences between DirectQuery and ROLAP).

It looks like DirectQuery mode doesn’t fit all circumstances, but there are a few cases in which it makes a lot of sense.

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SQL Server 2016 RC1 Available

Published 2016-03-21 by Kevin Feasel

Microsoft quietly announced SQL Server 2016 RC1 is available:

In SQL Server 2016 RC 1, we made enhancements to SQL Server Reporting Services, including:

  • Updated preview of the new web portal: The new web portal by default, and the classic Report Manager now removed.  Additionally, open the Mobile Report Publisher and Report Builder from the new web portal using any modern browser.

  • Custom branding: Customize the web portal with your organization’s logo and colors.

  • KPIs and mobile reports: Click a KPI and see a view with more details, and connect KPIs and mobile reports to parameterized datasets.

  • Modern paginated reports: Design beautifully modern paginated reports with new, modern styles for charts, gauges, maps and other data visualizations.

It looks like Reporting Services is getting to release shape.

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String_Split Performance

Published 2016-03-21 by Kevin Feasel

Aaron Bertrand looks into how STRING_SPLIT performs compared to other string splitting methods:

So with those limitations out in the open, we can move on to some performance testing. Given Microsoft’s track record with built-in functions that leverage CLR under the covers (coughFORMAT() cough), I was skeptical about whether this new function could come close to the fastest methods I’d tested to date.

Let’s use string splitters to separate comma-separated strings of numbers, this way our new friend JSON can come along and play too. And we’ll say that no list can exceed 8,000 characters, so no MAX types are required, and since they’re numbers, we don’t have to deal with anything exotic like Unicode.

The results are surprising.  I expected it to be somewhere around CLR-level, but not way better.

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Live Query Stats Versus Actual Execution Plans

Published 2016-03-18 by Kevin Feasel

Kendra Little compares and contrasts Live Query Statistics against actual execution plans:

Getting plan details isn’t free. The amount of impact depends on what the query is doing, but there’s a stiff overhead to collecting actual execution plans and to watching live query statistics.

These tools are great for reproing problems and testing outside of production, but don’t time query performance while you’re using them– you’ll get too much skew.

Live Query Statistics is one additional tool, but won’t replace actual execution plans.  At its best, it will make you think more about what’s going on with the system, whether row counts are what you’re expecting, and take account of which operators stream data through without blocking (such as nested loop joins) versus those which require all the data before continuing (sorts).

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Power BI Auto-Installation

Published 2016-03-18 by Kevin Feasel

Simon Sabin uses Powershell to install Power BI:

Having recently been having rebuilding my machine I finally decided to automate the process of installing the software I need.

This was a life saver as I was reinstalling a few times to try and figure out why I wasn’t getting sound on my external monitor. So I was gradually uninstalling everything until I found out that it was Hyper-v that was causing the problem.

The outcome meant I was installing PowerBI lots and had to automate it.

This looks like the first step toward a Chocolatey script.

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Joining On NULL

Published 2016-03-18 by Kevin Feasel

Erik Darling has opened a can of worms here:

WITH ALL THE TROUBLE NULLS CAUSE…

You’d think people would be more inclined to avoid them. Slap a NOT NULL constraint and a default value on your column and call it a day. I’m perfectly fine with bizarro world canary values. If it’s an integer column, some really high (low?) negative number. If it’s date-based, why not have it be the lowest value your choice accomodates?

Check out the comments, definitely.  I don’t think it’s as clear-cut as Erik argues; the idea of NULL has been and will remain controversial because it’s a useful concept but one which requires explicit consideration.

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SQLPS Update

Published 2016-03-18 by Kevin Feasel

Chrissy LeMaire has an update on SQLPS and SQL Server Linux:

  • Microsoft is investigating options for a cross-platform lightweight SQL Management Studio GUI tool for Linux.

  • Microsoft is investigating open sourcing the SQL Server PowerShell provider and cmdlets, and that it “makes a lot of sense” and “aligns with what Microsoft has already done with our Azure PowerShell cmdlets on github.” This is being tracked by connect item 2442788.

  • Microsoft doesn’t have dates or more details to share for any of these items at this time and will keep the community updated on their progress as they continue to evaluate our plans based on customer feedback

I’m most interested in the first of these points, but this is all interesting news.  Also check out her guest appearance on the PowerScripting Podcast.

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Find Object Dependencies

Published 2016-03-18 by Kevin Feasel

Manoj Pandey has pulled out the code used in Management Studio to get dependencies:

And here is a very lengthy (~900 lines) T-SQL Code that I generated from SSMS & SQL Profiler to check the same Dependencies of a Table in SQL Server 2014. You can also create a Stored Procedure and apply the Table & Schema as parameters.

You can just replace the Table & Schema in the first 2 lines and execute the code to check table dependencies

You might be able to optimize this script, but it’s nice to have a starting point.

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Nested Display Folders

Published 2016-03-18 by Kevin Feasel

Koen Verbeeck shows how to use nested display folders in Analysis Services and get Power BI to use them as well:

On the same day, I also found out it’s possible to nest display folders in SSAS. Which was even better, because I have a project with dozens of measures and this functionality really makes the difference. All you have to do is putting backslashes to indicate where a new child folder begins

This makes intuitive sense, so good on Microsoft for supporting this.

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