SQL Window Functions Series: LAG() and LEAD()
Dive deep into the powerful SQL window functions, LAG() and LEAD(). Explore their intricacies, discover real-world examples, and avoid common pitfalls.
2023-12-11
9,164 reads
Performance Tuning
Analyze and Tune SQL Server Statistics
Over the years, SQL Server Statistics have been discussed in countless blog posts, articles, and presentations, and I believe that they will remain a core topic for a while when speaking about performance. Why is that?
2023-10-04
SQL Server Execution Plan Issues when using TOP Clause and Various Parameters
A query is sometimes super fast and sometimes very slow. One of the main reasons for this problem is Parameter Sniffing. There are several approaches to addressing the Parameter Sniffing issue and this article discusses effective methods for handling Parameter Sniffing in SELECT statements containing a TOP clause.
2023-09-18
Comparing Two Execution Plans
This is a short look at a technique that I discovered recently in Management Studio (SSMS). The technique is to compare two graphical execution plans in the tool to understand what they are doing and how two different queries might affect a particular system, both with the image and with the properties' data behind the […]
2023-11-24 (first published: 2021-03-30)
10,592 reads
SQL Server SET STATISTICS IO ON Deep Dive
In this article we look at how to interpret and use the results of STATISTICS IO when tuning SQL Server queries.
2021-02-17
Digging Into Internals
There are plenty of experts that look to teach you about query tuning and the internals of query execution in SQL Server.
2020-07-18
162 reads
A simple use case for Columnstore Indexes in SQL Server
In this article we look at different use cases for columnstore indexes like when performing SQL Server count * queries.
2020-01-17
Optimize Your SQL by Reformulating the Spec
As SQL developers, we tend to think of performance tuning in terms of crafting the best table indices, avoiding scalar and table valued functions, and analyzing query plans (among other things). But sometimes going back to the spec and applying some properties of elementary math can be the best way to begin to improve performance of SQL queries which implement mathematical formulas. This article is a case study of how I used this technique to optimize my SQL implementation of the Inverse Simpson Index.
2021-05-07 (first published: 2019-09-12)
5,389 reads
The Basics - Level 1 of the Stairway to Query Store
Introduction Instead of going straight into the topic of the Query Store, I would like to start this Stairway Series by mentioning a few performance tuning scenarios that are very common to production DBAs. I think most of us have been in one of these situations at some time: An application experiencing slowness after a […]
2020-10-07 (first published: 2019-05-13)
6,894 reads
IGNORE_DUP_KEY slower on clustered indexes
The IGNORE_DUP_KEY option for unique indexes specifies how SQL Server responds to an attempt to INSERT duplicate values: It only applies to tables (not views) and only to inserts. Any insert portion of a MERGE statement ignores any IGNORE_DUP_KEY index setting.
2019-04-05
Blogs
Fix Slow, Bloated MSDB: Purge Old History And Add Missing Indexes
By SQLPals
Fix Slow, Bloated MSDB: Purge Old History And Add Missing Indexes ...
Three Ways to Use Snowflake Data in Microsoft Fabric
By James Serra
Organizations increasingly want Snowflake and Microsoft Fabric to coexist without duplicating data or fragmenting...
Deploying an Updated Model with SQL Compare 16
By Steve Jones
In a previous post, I deployed a model to a database using SQL Compare...
Forums
Automating Database Cleanup for PostgreSQL Using Python
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The Query Optimizer and Page Density
Comments posted to this topic are about the item The Query Optimizer and Page...
There Are a Lot of Databases
Comments posted to this topic are about the item There Are a Lot of...
Question of the Day
The Query Optimizer and Page Density
If I have a fillfactor set to 70%, this reduces my page density to roughly 70%. Does this affect the query plans that the optimizer chooses?
See possible answers