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Day: September 13, 2023

A Primer on Vector Search

Published 2023-09-13 by Kevin Feasel

Phil Booth takes a look at vector search systems:

Recently I built a system that uses vector search to logically truncate long documents and retain the most significant parts according to some search term. I’m a dummy, with no background in machine learning or mathematics, so there were new concepts for me to understand and implementation details to figure out. This post summarises what I learned.

Vector search and vector databases are becoming a fairly hot topic, so this at least grounds you on what they are.

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The Joy of sp_HumanEvents

Published 2023-09-13 by Kevin Feasel

Erik Darling makes a pitch:

While my relationship with Extended Events is complicated for many reasons:

  • Awful documentation
  • Hardly any guidance on usage
  • Almost nothing useful about what type of target to use when
  • Everything stored in XML
  • Slow, unfriendly GUI in SSMS

My need to use them while consulting outweighs my gripes and grievances about how Microsoft has chosen to write about, use, and present the data to you.

That’s where my stored procedure sp_HumanEvents comes in handy.

In fairness, Erik put his virtual money where his virtual mouth is, and sp_HumanEvents is put together quite well.

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Capturing Autogrowth Events in SQL Server

Published 2023-09-13 by Kevin Feasel

Ben Miller shares an extended event session with us:

I wanted to share one of the Extended Events I always put on a server when I am in charge of it. It has to do with File growths and captures some important things for me. Before you say that it is in the system_health extended events session, I know that it is there. I have had system_health sessions cycle pretty fast and there are a lot of other events in that trace, so I decided to make my own for just that specific thing so that I can archive the sessions and keep the disk clean as well as pull this information into a table and analyze data in a tabular way instead of mining XE files.

Read on for that script and what it does in practice.

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Restoring Azure SQL DB Indexes

Published 2023-09-13 by Kevin Feasel

Brent Ozar answers a question:

I got an interesting request for consulting, and I’m going to paraphrase it:

We were using Azure SQL DB with automatic index tuning enabled for months. Things were going great, but… we just deployed a new version of our code. Our deployment tool made the database schema match our source control, which… dropped the indexes Azure had created. How do we get them back?

Read on for Brent’s answer.

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A Primer on Latch Waits

Published 2023-09-13 by Kevin Feasel

Kendra LIttle gives us a sneak peek:

I’ve long found it tricky to remember and explain the differences between three similar-sounding waits in SQL Server that all have “LATCH” in the name: PAGELATCH, LATCH, and PAGEIOLATCH waits.

Here’s an illustration that explains these waits, along with wait subtypes.

This is an excerpt from my new comic, “Wait Stats in SQL Server.”

Click through for the excerpt, as well as some more detail on these latch types.

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