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Curated SQL Posts

Resource Governor and Memory Grants

Published 2021-01-29 by Kevin Feasel

Deepthi Goguri explains how you can use Resource Governor to control memory utilization:

Queries doesn’t start unless available memory is 150% of requested query memory because sql server will always allocate a little bit of additional buffer memory. Lets take the 100MB query which will get 150MB with additional buffer. What if this query only get 100MB and doesn’t get that additional buffer in the beginning to run the query? In that case, the query will wait until the 25x the query cost which is in seconds. When the timeout occurs and if the exact grant (100MB) is available without the buffer amount then the query starts to run this time. In other scenario, even after waiting for so long and after the timeout, the exact memory (100MB) without the memory grant is not available and less than 100MB is available, in that case the grant can be decreased to the minimum required grant. What if even the minimum required grant is not available, in that case we will receive an error 8645. We can configure the timeout by using the resource governor.

Read on for more detail.

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Refreshing Power BI Report Server Reports

Published 2021-01-29 by Kevin Feasel

Aaron Nelson has some new cmdlets for us:

I just wanted to give everyone a heads-up that a new version of the ReportingServicesTools module went out last week, and it includes 3 new PowerShell functions for working with Power BI reports on a Power BI Report Server (PBIRS) instance.

You can now Create (New), Get, & Start a CacheRefreshPlan of a Power BI report deployed to a PBIRS instance.  For clarity, these only apply to reports using an Imported model, not those using Direct Query.

Click through for more detail.

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Improving Triggers

Published 2021-01-29 by Kevin Feasel

Ed Pollack tries to improve our usage of triggers:

SQL Server triggers are a subject of both functionality and controversy on any database platform. They can provide immense utility at a low cost, but are often misused by developers, DBAs, and architects alike, resulting in performance bottlenecks or maintainability challenges.

This article briefly reviews DML (data manipulation language) triggers and delves into a discussion about how triggers can be efficiently and effectively used as well as when triggers can dig developers into holes that are hard to escape.

Read the whole thing. Triggers are rather useful tools when used correctly, but it’s easy to misuse them on accident.

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Modifying a Linked Entity in Power BI Dataflows

Published 2021-01-29 by Kevin Feasel

Reza Rad gives us a method to modify linked entities in Power BI dataflows:

It is not possible to change a linked entity in a dataflow in Power BI. Linked entities has to be modified only in the dataflow in which they are created. However, sometimes, you need to do a small modification to the linked entity in a chained dataflow. There is a very simple trick, In this article and video, I’ll explain how you can do that.

Read on to see how.

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PASS Under New Ownership

Published 2021-01-29 by Kevin Feasel

Steve Jones announces that Redgate is the captain now:

Redgate Software confirmed today that it has acquired the assets of the Professional Association for SQL Server (PASS), which ended operations on January 15, and will revive the Summit, continue SQLSaturdays, and make available the library of content and training sessions.

Note that this will be different from PASS as it existed, so membership in the old association doesn’t carry over to the new. If you’re interested in keeping up to date on this, check out https://www.red-gate.com/PASS.

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Rule 42 Software

Published 2021-01-28 by Kevin Feasel

John Mount describes a software development anti-pattern:

As software changes, it often accretes feature and drifts away from its design, if it even started with one, and many defaults and settings become undesirable. New users are blamed for not moving parameter settings away from the defaults to the “obvious” acceptable values.

Click through for the origin of the name and more info on how to avoid it.

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Parquet 1.x Footer Content

Published 2021-01-28 by Kevin Feasel

Dmitry Tolpeko shows us what the footer of a Parquet 1.x file looks like:

Every Parquet file has the footer that contains metadata information: schema, row groups and column statistics. The footer is located at the end of the file.

A parquet file content starts and ends with 4-byte PAR1 “magic” string. Right before the ending PAR1 there is 4-byte footer length size (little-endian encoding):

Click through for more details, as well as one downside to Parquet 1.x.

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Automating Data Comparison using Biml

Published 2021-01-28 by Kevin Feasel

Ben Weissman gives us an example of running data comparison using Biml:

When you build an ETL Solution, at some point you will most likely feel the need to compare the data between your source and your staging (or datawarehouse) database. There may be various reasons for them to be out of sync, such as delta loads, aggregations or added business logic, but one day your phone will ring and whoever is on the other end will tell you that the numbers are wrong. While this doesn’t necessarily have to be an issue within your ETL process, it might just as well be the report itself. In many cases, this is a good starting point to look at.

This article (formally published on PASS Community Blog) focusses on SSIS as your orchestrator, but the same principles could, obviously, also be applied to Azure Data Factory for example. Also, as we want to solve this task as lightweight as possible, we will, demonstrably, use Biml to implement it!

Click through to see how.

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