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Curated SQL Posts

Autostart XE With Powershell

Rob Sewell shows us how to set a particular extended event to start automatically when SQL Server starts up:

Very quick and simple and hopefully of use to people, this could easily be turned into a function. The full script is below and also available here on the Powershell gallery or by running  Save-Script -Name Set-ExtendedEventsSessionstoAutoStart -Path <path>

This is indeed a quick and easy script, and quite useful when checking across a large number of instances.

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Memory Pressure

Thomas Rushton walks us through determining if there’s memory pressure on an instance:

If you’ve been paying attention, you’ll have noticed that I’ve done the rownumbering in reverse order, and added a dummy (RowNum 0) field at the top of the list – this is to make sure that, if the most recent record is a RESOURCE_MEMPHYSICAL_LOW record, that we can get results that include that value.

This all looks OK in theory. But we’re still getting stupidly high values for the SecondsPressure field, and wait – what’s this? Multiple ring buffer records with the same ID?

More importantly, he shows us how bad the situation is:  is this something that happened for a couple of seconds, or is it persistent?  This is a great walkthrough.

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SSAS Auditing

Matt Smith links to Analysis Services auditing details and includes an audit table:

There are various types of Auditing in the Microsoft BI stack. There is auditing in SSRS, SharePoint, SSAS and not forgetting SQL has its own auditing.

Today I am looking at the SSAS auditing – you can find out more about it onTechNet.

Olaf Helper has published some TSQL code for querying the audit data -on theScript Center.

Just because it’s in a cube doesn’t mean we shouldn’t be able to audit it.

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Analyze In Excel

Avi Singh notes that Power BI will soon allow you to analyze data sets in Excel:

As a Modern Excel enthusiast (Modern Excel = Excel + Power Pivot + Power Query = Magic!), I found myself hesitant in embracing the new world of Power BI. Many of those inhibitions have shed away as Microsoft has continued to innovate and deliver an outstanding experience with Power BI. But I could not get over the feeling that going from Excel to Power BI felt like a one-way street.

You could upload/import an Excel Power Pivot model into Power BI desktop or onto PowerBI.com. But then you could not get it back. You could not get it back in Excel. In thefirst blog post on the site (yes the very first) Rob called us gridheads, and that we are.

Excel is still the top tool for business users.  Anything you can do to make life easier for your Excel users makes life easier for you as well.

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satRdays

Steph Locke notes that the R Consortium has agreed to support satRdays:

I’m very pleased to say that the R Consortium agreed to the support the satRday project!

The idea kicked off in November and I was over the moon with the response from the community, then we garnered support before submitting to the Consortium and I must have looped the moon a few times as we had more than 500 responses. Now the R Consortium are supporting us and we can turn all that enthusiasm into action.

This is great.  I’m looking forward to this taking off and being a nice complement to SQL Saturdays in cities.

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HIBPwned

Steph Locke has created an R package to query Troy Hunt’s Have I Been Pwned? site:

The answer in life to the inevitable question of “How can I do that in R?” should be “There’s a package for that”. So when I wanted to query HaveIBeenPwned.com (HIBP) to check whether a bunch of emails had been involved in data breaches and there wasn’t an R package for HIBP, it meant that the responsibility for making one landed on my shoulders. Now, you can see if your accounts are at risk with the R package for HaveIBeenPwned.com, HIBPwned.

This is a nice confluence of two fun topics, so of course I like it.

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Getting Started With Hadoop

Ginger Grant has some pointers on getting started with the Hortonworks Data Platform sandbox:

Previously, spinning up a virtual machine meant purchasing software. No more, as there is now an open source application. In the example shown here, the Linux operating system will be installed, you can put any operating system you want on your virtual machine, provided of course you have a license for it. If you don’t feel comfortable installing non-released versions of code like SQL Server 2016, on your pc, a virtual machine is a great way to test it out. You will need to provide your own operating system, but there are trial versions you can use for limited periods of time as well. The open source virtual machine Oracle VM Virtual Box is the only open source version of a virtual machine software. You can download it here. This software is needed prior to installing the Hortonworks Sandbox. Obviously Hortonworks is not the only version of Hadoop available, Cloudera has a Hadoop VM too, which you can download as well. Personally I am not a use fan of the Cloudera Manager, which is why I prefer Hortonworks, but either will work with polybase.

I’m personally a fan of VMware Player for VMs, but either will work well for the task.

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Remember Partition Alignment

Kendra Little shows that truncating partitions in SQL Server 2016 requires all indexes be aligned to the partition:

If you have a non-aligned index on the table, you’ll see an error like this:

Msg 3756, Level 16, State 1, Line 1

TRUNCATE TABLE statement failed. Index ‘ix_FirstNameByBirthDate_pt_BirthYear_FirstNameId_nonaligned’ is not partitioned, but table ‘FirstNameByBirthDate_pt’ uses partition function ‘pf_fnbd’. Index and table must use an equivalent partition function.

This isn’t a bug, and it makes total sense from a logical point of view. “Non-aligned” indexes are not partitioned like the base table is– by definition they are either partitioned differently, or not partitioned at all. The chunk of data that you’re trying to truncate isn’t all in an easily identifiable partition that can be quickly marked as “data non grata”. There’s just no way to do a simple truncate when the data’s scattered all around.

Ideally, all indexes on a partitioned table would be partition-aligned, as it makes maintenance a lot easier.  That’s not always possible, though, so keep this in mind.

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New In-Memory OLTP Features

Jos de Bruijn points out new In-Memory OLTP features introduced since CTP3:

Large object (LOB) types varchar(max), nvarchar(max) and varbinary(max) are now supported with memory-optimized tables and table types, as well as natively compiled T-SQL modules, and the size limitations mirror that of disk-based tables (2GB limit on LOB values). In addition, you can have a memory-optimized table with a row size > 8060 bytes, even when no column in the table uses a LOB type. There is no run-time limitation on the size of rows or the data in individual columns; this is part of the table definition. Of course, all data does need to fit in memory.

I’m very pleased about this—now I can go back and turn some of my bigger table types into memory-optimized table types.

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Using The DAC

Andrea Allred shows us how to use the DAC:

The DAC, what is it? It is the Dedicated Administrator Console. Basically it is a way to connect to your SQL Server when all the other connections are tied up. But it takes a little bit of pre-planning so that you can use it when things go bad with your SQL Server.  Let’s enable it so you can test using it and know that it is there in the future.

This is your “get out of jail free” card when the instance is completely unresponsive.  A small amount of memory is dedicated to the DAC so that even if anything else is locked up, you have a chance to fix the problem short of a reboot.

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