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Showing posts with label Procedures. Show all posts
Showing posts with label Procedures. Show all posts

Wednesday, 15 August 2012

Temporary Table Caching in Stored Procedures

Temporary Table Caching in Stored Procedures

Introduction

Ask anyone what the primary advantage of temporary tables over table variables is, and the chances are they will say that temporary tables support statistics and table variables do not.

This is true, of course. The indexes that enforce PRIMARY KEY and UNIQUE constraints on table variables do not have populated statistics associated with them. Neither do any non-constraint table variable indexes (using inline index definitions, available starting with SQL Server 2014). Finally, it is not possible to manually create statistics on table variables.

Intuitively, then, any query that has alternative execution plans to choose from ought to benefit from using a temporary table rather than a table variable. This is also true, up to a point.