Brent Ozar • 8/6/2026

Database Animations: Why Big Columns May Not Affect Logical Reads

This article by Brent Ozar discusses how adding wide columns to SQL Server tables, such as JSON or XML, can be stored off-row to avoid impacting logical reads during queries that don't reference them. It explains the mechanics of row size, 8KB pages, and the sp_tableoption setting 'large value types out of row' to force off-row storage. The article includes visual animations comparing on-row vs off-row storage and highlights scenarios where this optimization is beneficial, such as when large columns are rarely selected. It also touches on the trade-offs and practical considerations for database design.

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#indexing #SQL Server #T SQL