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Microsoft® SQL Server® 2008 Internals by Paul Randal Kalen Delaney Kimberly Tripp, and Conor Cunningham

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Caching Mechanisms

SQL Server can avoid compilations of previously executed queries by using four mechanisms to make plan caching accessible in a wide set of situations:

  • Adhoc query caching

  • Autoparameterization

  • Prepared queries, using either sp_executesql or the prepare and execute method invoked through your API

  • Stored procedures or other compiled objects (triggers, TVFs, etc.)

To determine which mechanism is being used for each plan in cache, we need to look at the values in the cacheobjtype and objtype columns in the sys.dm_exec_cached_plans view. The cacheobjtype column can have one of six possible values:

  • Compiled Plan

  • Compiled Plan Stub

  • Parse Tree

  • Extended Proc

  • CLR Compiled Func

  • CLR Compiled Proc

In this section, the only values we are looking at are ...

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