Fixes for Adaptive Features are included in Oracle October 2017 BP

Finally … the two most important fixes for Adaptive Features are included in Oracle October 2017 BP (Bundle Patch). I’m absolutely happy about this. Almost all of my customer and many folks outside I’m dealing with on a regular basis had to request and wait for merge patches over and over again. And we all knew – also based on the experience of the Real World Performance Team – that these two patches are so important to stabilize Oracle production systems.

You may find this ALERT on MyOracle Support:

MOS Note 2289719.1
ALERT: Oracle Recommended Adaptive Feature Configuration Parameter Settings for

Which fixes are included?

Besides some other fixes these important fixes are included:

Please see this blog post for details and further links about the patches, and why you need to apply them – or better use the October 2017 BP: Enabling Oracle 12.2 Adaptive Features in Oracle

Where are these fixes included?

The fixes are included in the Oracle Database Proactive Bundle Patch (BP). They are NOT included in the PSUs. And they are not included in Oracle 12.2 RUs as there’s no need to include them. This is another reason why you should switch from PSUs to BPs whenever possible.

Interestingly enough the fixes were included already in the Windows Bundle Patches since the August 2017 BP.

Please note that these fixes are disabled by default. But with the new Automatic Fix Control Persistence Framework once you enable them they’ll stay enabled when you apply subsequent Bundle Patches.

More information?

Of course you will find more information in the README for Database Proactive Bundle Patch Patch 26635880. I quote it here:

This patch is supported by 12.2 adaptive features behavior in, but these changes are kept by default off. See My Oracle Support Document 2312911.1 Recommendations for Adaptive Features in Oracle Database 12c Release 1 (Adaptive Features, Adaptive Statistics & 12c SQL Performance) (Doc ID 2312911.1) for more information about how to use 12.2 adaptive features behavior in provided by the Database Proactive Bundle Patch.

Further information is provided in MOS Note: 2312911.1 – Recommendations for Adaptive Features in Oracle Database 12.1.

See also David Kurtz‘ (Accenture – Enkitec) experiences with Oracle PeopleSoft installations using the Adaptive Features fixes:

What is your task now?

It’s very “simple”:

  1. Apply Database Proactive Bundle Patch Patch 26635880.
  2. Remove a potentially existing parameter optimizer_adaptive_features from your SPFILE.
  3. Switch on the patches. Please see MOS Note: 2312911.1 for detailed options.
    Either add to your init.ora/spfile: *._fix_control='26664361:7','16732417:1','20243268:1'
    Or use: alter system set "_fix_control"='26664361:7','16732417:1','20243268:1' scope=both;
    Be VERY careful not delete other fix control entries if any exist. This command will overwrite existing _fix_control settings.
  4. In addition OPTIONALLY you may enable also the other optimizer fixes included.
    Please see DBMS_OPTIM_BUNDLE – only available in Oracle on how to display and enable the other fixes in addition.
  5. Restart the database. This is required in order to enable the fixes correctly.
  6. Finally run the script execstat.sql:
    connect / as sysdba

You should be good by using the defaults for optimizer_adaptive_statistics=FALSE and optimizer_adaptive_plans=TRUE.

Be aware if you had optimizer_adaptive_features=FALSE before applying this BP you may encounter now plan changes due to optimizer_adaptive_plans=TRUE by default. I’d recommend to test and keep an eye on it but giving it a try. Actually two of my Oracle 12c reference customers have exceptionally good experiences with the “plan” part of the adaptive features.

And one last thing:
If you have an Oracle Multitenant deployment with Oracle and plan to enable the highly recommended “adaptive” fixes AND the fixes under control of DBMS_OPTIM_BUNDLE you must edit your init.ora/SPFILE as otherwise the two calls overwrite each other vice versa. I’ll file a bug these days.


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