An adventure on SQL Server performance and features

T-SQL Tech

An adventure on SQL Server performance and features

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Tracking Dynamic SQL performance automatically with a wrapper on sp_executesql (Dynamic SQL Inception)

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in some projects I have a lot of Dynamic SQL going on, some queries are fast, some queries are slow, it depends on how the dynamic statement is actually put together ¯\_(ツ)_/¯ Tracking the performance of such statements is usually difficult because you don’t really know “why it’s slow” and you have to interpolate data from the app and the plan cache (if the plan is still...

Creating a Perfmon and Filestats reports in PowerBI [Part 2]

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In this previous post I detailed the structure of the objects to be created to create a live report in PowerBI to analyze Perfmon and Filestats data (which in my case was already being gathered but not used by the FirstRespondersKit tool); Let’s get to the PowerBI stuff. Here is the final result that we’ll reach: I’ll be starting from the existing FirstRespondersKit PowerBI...

A clarification on the waitstat: SOS_SCHEDULER_YIELD

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Are you one of the people that says “we have a CPU related issue” whenever it sees SOS_SCHEDULER_YIELD popping up? Let me explain why you’re wrong. In the books online, SOS_SCHEDULER_YIELD is defined simply as: Occurs when a task voluntarily yields the scheduler for other tasks to execute. During this wait the task is waiting for its quantum to be renewed. Well, since the SQL...

Revisiting the classics: Minimizing the Impact of DBCC CHECKDB (by Aaron Bertrand) in 2018

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SQL Server has a long history, it has been around since the ’90, more than 20 years have passed, which is a VERY long time as far as the IT world goes; Especially now that Microsoft has stepped up the release schedule for SQL Server (releases are now scheduled yearly) I thought that maybe it’s a good time to go back and revisit the classic articles and recommendations by the Gurus of...

What’s the best way to massively update a big table?

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A thing that can happen once in a while in a DW is the need to massively update a column in a table, let’s find out. I’ll be using the same table as last post , the lineitem table of the tpch test by HammerDB, the three contenders are: Heap Clustered Index Clustered Columnstore Index No other NonClustered index will be included in the base table. You should already know that each...

Test: confronting various methods of bulk loading data from a table to another, what’s the fastest?

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 Most of the support request I get involved with can be summarized with the following keywords: “slow” + “datawarehouse” + “ETL” + “Save us” What about thinking about ETL performance before it goes bad? Before the system is in production for some time , the data size reaches a decent size which wasn’t tested in DEV and you find out that the...

Can a single query deadlock itself? Apparently, yes: A curious case of Intra-query Parallelism

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Imagine that you’re in a SQL data warehouse in the middle of the night, a single stored procedure is running, is nothing else, and it’s simply doing inserts and updates, one statement at the time, but then.. Deadlock. How can it be? Something else must be running, right? Someone launched something else, or a transaction was left open the day before, or the Russians were spying...

Scan Performance Showdown: INROW Predicate pushdown VS Batch Mode Adaptive Join vs Columnstore indexes

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I was reading Paul White’s post about bitmaps in SQL Server and, other than realizing that I basically know nothing about anything (like a Socrate’s epiphany) I wanted to at least see how this good stuff added up in the latest 7 years. Down with experimenting, we’re doing this LIVE! (Well, it’s live for me, for you it’s still a blog post) I’ll start by creating...

Creating a Perfmon and Filestats reports in PowerBI [Part 1]

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If you work for a big company, you may have a bunch of instances/databases under your control, you ran whatever monitoring tool has been provided and everybody is happy; But if your’re like me and you’re working for a big number of customers, each one with a different version of SQL and own configuration/security policies, with no monitoring tool directly available, and have to answer...

An adventure on SQL Server performance and features

Emanuele Meazzo

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