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Month: January 2017

Sorting By Column In Power BI

Published 2017-01-12 by Kevin Feasel

Reza Rad explains how to sort a column by another column’s value in Power BI visuals:

Problem happens when you want a Text field to be ordered based on something different than the value of the field. For example if you look at above chart you can see that months ordered from April to September. This is not order of months, this is alphabetical order. If you change the sorting of visual, it will only change it from A to Z, or Z to A. To make it in the order of month numbers you have to do it differently.

Read on for the solution.

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Delay Between Responses

Published 2017-01-12 by Kevin Feasel

Monica Rathbun begins a new challenge by describing the importance of one tiny form control:

When I worked at the Port of Virginia, I was a little less experienced in SQL and didn’t notice this lovely little option. I of course failed to set it. Can anyone guess what happened? YEP, we got low on resources in the wee hours of the morning and SQL kicked off an Error 017-Insufficient Resources. Thousands of emails were generated and caused the Exchange server to go down as well as some other issues that arose because of this. The worst part is that all the emails had to finish processing before we could delete them from the system. I think when all was said and done there was well over 250k messages it created.

She also includes a list of important alerts; just make sure to set the delay.

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Query Store Connect Items

Published 2017-01-12 by Kevin Feasel

Erin Stellato link to two feature requests for Query Store:

Two of these requests have Connect items, which I’m listing below.  The first allows you to change the location of Query Store data to reside somewhere in the user database besides the PRIMARY filegroup:

Option to store query store data in a filegroup other than PRIMARY

The other request is related to exporting that data, which is technically possible now, but it’s not a supported method so it’s not something I really want to implement in a client environment.  I’ve had many people describe their process for testing which includes restoring database nightly.  If they’re using Query Store as part of testing, that data is lost every night by the restore.

Export Query Store tables separately from the database tables

Click through for more and vote up those items relevant to you.

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Wanted: MDX Intellisense

Published 2017-01-12 by Kevin Feasel

Jens Vestergaard wants Intellisense for MDX:

The Connect Item I have chosen to write about is an old one and is about getting Intellisense for MDX in SQL Server Management Studio [SSMS]. Despite the fact that it was created back in 2009 by Jamie Thomson (b|l|t), it is still active and there has been a public acknowledgement back then, by the Analysis Service Team, that they will consider this request for an upcoming release. 2009, still active… True story.

Read on for more details and be sure to join Jens’s quixotic quest if you’d like to see MDX Intellisense.

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Subset And Apply Problems

Published 2017-01-11 by Kevin Feasel

Tom Martens explains a class of generic data processing problems:

Subset and Apply means that I have a dataset of some rows where due to some conditions all the rows have to be put into a bucket and then a function has to be applied to each bucket.

The simple problem can be solved by a GROUP BY using T-SQL, the not so simple problem requires that all columns and rows of the dataset have to be retained for further processing, even if these columns are not used to subset or bucket the rows in your dataset.

One quick example of this is running totals of orders for each customer, which Tom answers using T-SQL, R, and Power BI.  Click through for those three solutions.

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Event Handling Items

Published 2017-01-11 by Kevin Feasel

Dave Mason looks at two Connect items related to working with extended events:

One Event Behind

I another post, I wrote that the XEvents event_stream target is regularly “one event behind”. There is an existing Connect item seeking a fix to this problem: QueryableXEventData and “Watch Live Data” one event behind. If you use the “Watch Live Data” grid for XEvents in SSMS, this is an important issue and worthy of your upvote. It’s also important if you ever want to access XEvent data programmatically with C# or PowerShell because the QueryableXEventData class uses the event_stream target and is also subject to the issue.

Read on for more details.

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Network Latency And Availability Groups

Published 2017-01-11 by Kevin Feasel

Anthony Nocentino discusses network latency and how that can affect Availability Groups:

Now let’s talk about Availability Group replication and network latency. Availability Groups replicate data over your network using Database Mirroring Endpoints which are TCP sockets used to move data between the primary and it’s replicas. When designing Availability Groups, we often think about things in terms of bandwidth…how much data do I need to move between my replicas. But there’s another design factor your need to consider, network latency. Why? Hint, it’s not going to have anything to do with synchronous availability mode and HADR_SYNC_COMMIT waits. Let’s talk about some fundamentals of TCP for a second.

Click through for some discussion of TCP fundamentals.

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Last Log Backup Time

Published 2017-01-11 by Kevin Feasel

Kevin Hill comments on a recent Connect item by Ola Hallengren:

And his proposed solution:

Add a new column to sys.dm_db_log_space_usage or sys.database_recovery_status called LastLogBackupTime.

I LOVE this idea…back up the T-log more frequently during busy times, less often during off hours.  At my current client, there is almost nothing happening outside of a 12 hour workday window, so this would be perfect here.

Now, I am possibly misunderstanding Ola’s request or the intent…and that’s ok.  This query from the msdb..backupset table already contains this info via a relatively short amount of code:

Click through for more details as well as Ola’s Connect item.

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Wanted: Named Parameters For Functions

Published 2017-01-11 by Kevin Feasel

Riley Major would like to be able to specify parameter names in function calls:

Now try this:

DECLARE
	@OrderID int = NULL,
	@OrderType int = 1,
	@Qty int = 2,
	@ServiceSpeed int = 3;

SET @OrderID = dbo.GetOrderID (@OrderType, @Qty, @ServiceSpeed);

SELECT @OrderID 'Using SET Syntax';

Now you get a NULL back from the final SELECT. What happened? If you are a careful code reviewer, you might have spotted that the function definition has the @Qty and @ServiceSpeed parameters flipped as compared to the table definition and how we’re calling the function.

But this isn’t an error. There’s no obvious indication that anything is wrong. Imagine if instead of NULL, which would probably break something, you got a different order ID back. Your program would silently continue, oblivious to what is essentially data corruption.

And if you build a function with a large number of parameters, it gets that much easier accidentally to swap just two of them.  Click through for the rest of the story, and check out Riley’s Connect item.

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Wanted: Unsigned Ints

Published 2017-01-11 by Kevin Feasel

Ewald Cress would like to have unsigned integer types:

Let’s take a look at what is being asked here. Using the 32-bit integer as an example, we currently have a data type that can accept a range between negative two billion and two billion. But if negative numbers aren’t required, we can use those same 32 bits to store numbers between zero and four billion. Why, goes the question, throw away that perfectly useful upper range by always reserving space for a negative range we may not need?

I appreciate Ewald’s thoughtfulness here in working out the value of the request as well as some of the difficulties in building something which fulfills his desire.  Great read.

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