Power BI Premium Released

Dustin Ryan reports that Power BI Premium is now generally available:

Microsoft stated that Power BI Premium would be GA late Q2 of 2017, which could mean nothing else aside from June. Well, today is the day that Power BI Premium, along with Power BI Report Server, are generally available.

Lucky for me, I have a user on a tenant with Power BI Premium capacity available for me to use. When you first log into your tenant after Power BI Premium capacity has been purchased, you are presented with the following welcome screen which includes a link to learn more about Premium capacity.

The Power BI team continues to be busy.

When Snapshots Begin

Kendra Little explains when a transaction really begins when you are in the snapshot isolation level:

  • 00.000 – Session A sets its isolation level to snapshot

  • 00.001 – Session A explicitly begins a transaction with BEGIN TRAN

  • 00.002 – Session A starts a WAITFOR command for 15 seconds

  • 10.000 – Before the WAITFOR completes, Session B inserts rows into dbo.Table

  • 15.001 – Session A starts a SELECT from dbo.Table, which returns the rows that Session B inserted

This seems wrong, because many of us commonly say things like, “in Snapshot Isolation level, all statements see data consistent with the beginning of the transaction.”

But in this case, Session B inserted the rows after Session A began its transaction using Snapshot Isolation level. So why did Session A see those rows?

Kendra explains the nuance well, so read the whole thing.

Security And Zookeeper

Michael Han describes a few methods you can use to tighten up (or rather, introduce) security in ZooKeeper:

Four Letter Words (acronym as 4lw) is a very popular feature of the Apache ZooKeeper project. In a nutshell, 4lw is a set of commands that you can use to interact with a ZooKeeper ensemble through a shell interface. Because it’s simple and easy to use, lots of ZooKeeper monitoring solutions are built on top of 4lw.

The simplicity of 4lw comes at a cost: the design did not originally consider security, there is no built in support for authentication and access control. Any user that has access to the ZooKeeper client port can send commands to the ensemble. The 4lw commands are read only commands: no actions can be performed. However, they can be computing intensive, and sending too many of them would effectively create a DOS attack that prevents the ensemble’s normal operation.

Read on for details.

Moving Docker Containers

Andrew Pruski shows how to change the default location for Docker containers on Windows:

There’s a switch that you can use when starting up the docker service that will allow you to specify the container/image backend. That switch is -g

Now, I’ve gone the route of not altering the existing service but creating a new one with the -g switch. Mainly because I’m testing and like rollback options but also because I found it easier to do it this way.

Read the whole thing.

Flattening JSON With Purrr

Steph Locke shows how to use purrr to write functional style code in R:

And… et voila! A multi-language dataset with the language identified and the sentiment scored using purrr for easier to read code.

Using purrr with APIs makes code nicer and more elegant as it really helps interact with hierarchies from JSON objects. I feel much better about this code now!

Purrr is something I really want to dig into for reasons just like this.

Cross-Platform Powershell Remoting

Anthony Nocentino shows how to enter Powershell sessions using OpenSSH-basted remoting:

Nothing special here, simple syntax, but the seasoned PowerShell remoting pro will notice that we’re using a new parameter here -HostName. Normally on Windows PowerShell you have the -ComputerName parameter. Now, I don’t know exactly why this is different, but perhaps the PowerShell team needed a way to differentiate between OpenSSH and WinRM based remoting. Further, Enter-PSSession now has a new parameter -SSHTransport which at the moment doesn’t seem to do much since remoting cmdlets currently use OpenSSH by default. But if you read the code comments here, it looks like WinRM will be the default and we can use this switch parameter to specify SSH as the transport.

Once we execute this command, you’ll have a command prompt to the system that passed as a parameter to -HostName. The prompt below indicates you’re on a remote system by putting the server name you’re connected to in square brackets then your normal PowerShell prompt. That’s it, you now have a remote shell. Time to get some work done on that server, eh? Want to get out of the session, just type exit.

It’s interesting to see how well Microsoft is integrating Linux support into Powershell (and vice versa, but that’s a different post).

Using OStress

Nikhilesh Patel explains how to use OStress to generate artificial database loads for stress testing:

OStress is a Microsoft tool comes with RML utilities package and it uses to stress SQL Server. This is especially useful when you want to troubleshoot SQL Server while SQL Server is under heavy load.

It is a free tool for SQL Server developers and DBAs. It is designed to assist with performance stress testing of T-SQL queries and routines. The tool automatically collects metrics to help you determine whether your queries will perform under load, and what kind of resource strain they put on a server. In short, it also allows putting a serious load on your database.

OStress isn’t the easiest thing in the world to set up, but it works well.

Change Detection With Hashes

Nigel Meakins shows how to use HashBytes to roll your own change detection:

So this all sounds very promising as a way of tracking changes to our Data Warehouse data, for purposes such as extracting deltas, inserts and updates to Type I and II dimensions and so forth. It doesn’t have any show-stopping overhead for the hashing operations for the sizes of data typically encountered and storage isn’t going to be an issue. It is native to T-SQL so we can rerun our hash value generation in the engine where our data resides rather than having to push through SSIS or some other tool to generate this for us. Algorithms are universal and as such will give us the same values wherever used for the same bytes of input. Let’s go back to the basic idea for a minute and consider how we implement this.

This is particularly useful in cases where you have metadata columns you don’t much care about (e.g., last modified time).  I do recommend using CONCAT or CONCAT_WS (if you’re on SQL Server 2017) to do string concatenation, though; it’d remove the need for util.CastAsNVarchar and possibly more.

Reading Dump Files With WinDbg

Arun Sirpal shows how to install and use WinDbg to read SQL Server dump files:

Disclaimer: I only issue basic commands, when in the WinDBG command line you can issue all sorts, but for someone like me there is no real point.

Select the file and let it go to work – you will see BUSY messages.

Really understanding how the debugger works is a great skill to have.


June 2017
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