optimization Archives - SQLPerformance.com

Optimization Thresholds – Grouping and Aggregating Data, Part 5

In the conclusion of his series on grouping and aggregation costs, Itzik Ben-Gan reveals some of the math behind seek vs. scan decisions.

Itzik Ben-Gan ◆ August 8, 2018

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Optimization Thresholds – Grouping and Aggregating Data, Part 4

In the fourth installment of his series on optimization thresholds, Itzik Ben-Gan looks at how SQL Server applies costs to parallel operations.

Itzik Ben-Gan ◆ July 11, 2018

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Optimization Thresholds – Grouping and Aggregating Data, Part 3

Itzik Ben-Gan dissects the Hash Match (Aggregate) algorithm in his latest post in a series on SQL Server optimization thresholds.

Itzik Ben-Gan ◆ June 13, 2018

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Optimization Thresholds – Grouping and Aggregating Data, Part 2

Continuing his series on optimization thresholds, Itzik Ben-Gan dives into the calculations behind stream aggregate costing when the data needs to be sorted first.

Itzik Ben-Gan ◆ May 9, 2018

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Locking and Performance

Paul White (@SQL_Kiwi) follows up a great post on calculating medians with some information on how locking can affect query performance, often undetected.

Paul White ◆ July 20, 2015

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StarJoinInfo in Execution Plans

Paul White (@SQL_Kiwi) relays some useful information about SQL Server execution plans that include StarJoinInfo.

Paul White ◆ January 27, 2014

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Working Around Missed Optimizations

Paul White (@SQL_Kiwi) continues his discussion about optimization and how recognizing transformations can help you make better decisions about potential query re-writes.

Paul White ◆ July 8, 2013

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Optimization Phases and Missed Opportunities

Paul White (@SQL_Kiwi) talks about optimization stages and explains how to get more insight into missed opportunities.

Paul White ◆ June 26, 2013

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The Halloween Problem – Part 4

The Halloween Problem has a number of important consequences for SQL Server execution plans. In this final part of the series, we look at some of the tricks the optimizer uses to avoid adding an Eager Table Spool to every update query that might encounter the Halloween Problem.

Paul White ◆ February 20, 2013

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