Carlos Sierra's Tools and Tips

Tools and Tips for Oracle Performance and SQL Tuning

Migrating an Execution Plan using SQL Plan Management

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SQL Plan Management (SPM) has been available since the first release of 11g. As you know SPM is the new technology that provides Plan Stability with some extra Plan Control and Management features. Maria Colgan has done an excellent job documented the “SPM functionality” pretty well in 4 of her popular blog postings:

  1. Creating SQL plan baselines
  2. SPM Aware Optimizer
  3. Evolving SQL Plan Baselines
  4. User Interfaces and Other Features

A question that I often get is: How do I move this good plan from system A into system B? To me, this translates into: How do I migrate an Execution Plan? And if source and target systems are 11g, the answer is: Use SQL Plan Management (SPM).

Migrating a Plan using SPM

Assuming both – source and target systems are on 11g then I suggest one of the two approaches below. If the source is 10g and target is 11g, then the 2nd approach below would work. In both cases the objective is to create a SQL Plan Baseline (SPB) into the target system out of a known plan from the source system.

Option 1: Create SPB on source then migrate SPB into target

Steps:

  1. Create SQL Plan Baseline (SPB) in Source
    1. From Memory; or
    2. From AWR (requires Diagnostics Pack license)
  2. Package & Export SPB from Source
  3. Import & Restore SPB into Target

Pros: Simple

Cons: Generates a SPB in Source system

Option 2: Create SQL Tuning Set (STS) on source, migrate STS into target, promote STS into SPB in target

Steps:

  1. Create SQL Tuning Set (STS) in Source (requires Tuning Pack license)
    1. From Memory; or
    2. From AWR (requires Diagnostics Pack license)
  2. Package & Export STS from Source
  3. Import & Restore STS into Target
  4. Create SPB from STS in Target

Pros: No SPB is created in Source system

Cons: Requires license for SQL Tuning Pack

How SQLTXPLAIN (SQLT) can help?

SQLT has been generating for quite some time a STS for each Plan Hash Value (PHV) of the SQL being analyzed. This STS for each PHV created on the source system is also stored inside the SQLT repository and included in the export of this SQLT repository. By doing this every time, options 1 and 2 above are simplified. If we want to promote a Plan into a SPB in source system we only have to execute an API that takes the Plan from the STS and creates the SPB. The dynamic readme included with SQLT has the exact command. And if we want to create a SPB on a target system having a SQLT from a source system, we have to restore the SQLT repository into the target system, then restore the STS out of the SQLT repository, and last create the SPB out of the STS. All these steps are clearly documented in the SQLT dynamic readme, including exact commands. There is one caveat although: you need SQLT in source and restore its repository in target…

Stand-alone scripts to Migrate a Plan using SPM

Options 1 and 2 above list the steps to take a plan from a source system and implement with it a SPB into a target system. The questions is: How exactly do I perform each of the steps? Yes, there are APIs for each step, but some are a bit difficult to use. That is WHY I have created a set of scripts that pretty much facilitate each of the steps. No magic here, only some time savings. If you want to use these scripts, look for SQLT directory sqlt/utl/spm, which will be available with SQLT 11.4.5.8 on May 10, 2013. If you need these scripts before May 10, then please send me an email or post a comment here.

Written by Carlos Sierra

May 2, 2013 at 8:02 am

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