Jeffry Schwartz, Author at SQLRx

About the Author

Jan 07

Disk Metrics – Why PerfMon’s, SQL Server’s Filestats, and Disk Vendors’ Values Sometimes Appear to Disagree

By Jeffry Schwartz | Expert , Performance Tuning , SQL Server , Windows

— By Jeffry Schwartz Whenever multiple data sources are used, actual or perceived discrepancies can arise. Sometimes this is due to the location of the data collector, e.g., Windows, SQL Server, or the disk array. Other times, it is due to the collection rate and whether the information is a simple recording of continuously incremented […]

Oct 15

Using Common Table Expressions to Improve Query Performance

By Jeffry Schwartz | Advice , Intermediate , Performance Tuning , SQL Development , SQL Server

-by Jeffry Schwartz Queries with multiple join clauses create particularly difficult issues when they perform poorly. Join ordering is extremely important because if a join creates a huge interim result set at the beginning of the query execution, SQL Server must continue to handle this result set until it can be trimmed down with filtering […]

Aug 13

The Pros & Cons of Hyperthreading

By Jeffry Schwartz | Advice , Miscellaneous , SQL Administration , Windows

— By Jeff Schwartz Hyperthreading is one of those features that most IT personnel have heard about, but many do not understand exactly what it does or why it may improve or degrade the performance of their servers. Although hyperthreaded processors have been available for many years, the confusion surrounding it is as commonplace today […]

Mar 16

Introduction to SQL Server Execution Plans

By Jeffry Schwartz | Miscellaneous , Performance Tuning , SQL Server

Recently, a coworker asked me about a query performance problem that had suddenly arisen as they so often do. During testing, this particular query had performed extremely quickly, but when it was shown to a C-level person, it dragged terribly making this impatient person wait 80 seconds for the answer to come back. We all […]

Feb 16

Top PerfMon Performance Counters for Determining Causes of Slow Response Times

By Jeffry Schwartz | Performance Tuning , SQL Server , Windows

Introduction Have you ever been placed in the position of being forced to address user complaints about how slow the system is performing without really knowing exactly where to begin looking? Some analysts begin with Task Manager or viewing the Windows event log. Others who are working with SQL Server search the ErrorLog for problems […]

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