Monday Nov 30, 2015

VBox 5.0.10 crash issues with our Hands-On-Lab

Milano - Nov 2015 (c) Mike Dietrich

I've ran two Hands-On-Workshops with customers and partners in Italy last week in Milano where we used our well known and thousands-of-times proven Hand-On-Lab environment

But this time some people failed while running the lab with random corruptions either shutting down the entire VM while running - or displaying file corruptions in the spfile - or other issues.

The common thing in all cases: People had VBox 5.0.10 downloaded and installed right before the workshop.

Of course they've did it - as I'm tempted too since weeks. Every time I start VBox on my PC Oracle Virtual Box asks me: 

Even though the screenshot is German you know what it offers me:
Download and Install Virtual Box 5.0.10.

Actually the current issue reminds me a lot on what I have experienced in 2014 in an Upgrade Hands-On Workshop in Vienna, Austria. 20 Oracle partners came together for two days for a Hands-On Upgrade/Migrate/Consolidate training. And 6 or 7 had random issues with their Virtual Box images. Corruptions. Failing upgrades at random phases. No patterns.

Only until somebody figured out via a Google search that at the same time other people started reporting similar behavior with their own VBox images using the brand new version of Virtual Box. It turned out that this newest version of Oracle Virtual Box 4.3 (I think it was 26) had exactly such issues. Everybody else in our room - including myself - running a version a few weeks older had no issues at all.

When we exchanged the affected installations the next morning replacing it (if I remember correctly: 4.3.24) all went fine for the rest of the workshop.

I won't say that VBox 5.0.10 is bad as I lack evidence, reproducible test cases, bugs. 

But I follow other people's Twitter and Facebook messages. And it seems to be that the PERL problem I did report a few days back:

is not he only issue with VBox images build in version 4 - and now running (more or less) on VBox 5.0.10.

Please see also:


Monday Nov 23, 2015

Network ACLs and Database Upgrade to Oracle 12c

What has been changed in Oracle Database 12c with Network ACLs?

Starting from 12c, network access control in the Oracle database is implemented using Real Application Security access control lists (ACLs). Existing 11g network ACLs in XDB will be migrated. Existing procedures and functions of the DBMS_NETWORK_ACL_ADMIN PL/SQL package and catalog views have been deprecated and replaced with new equivalents

In 12c, a network privilege can be granted by appending an access control entry (ACE) to a host ACL using DBMS_NETWORK_ACL_ADMIN.APPEND_HOST_ACE.  If you append an ACE to a host that has no existing host ACL, a new host ACL will be created implicitly. If the host ACL already exists, the ACE will be appended to the existing ACL.

(both paragraphs taken from MOS Note: 2078710.1)

What happens during/after upgrade?

  • Existing network ACLs will be migrated from XDB in Oracle 11g to Real Application Security in Oracle 12c.
    All privileges of the existing ACLs will be preserved
  • Existing ACLs will be renamed
  • Mapping between the old / new names is reflected in DBA_ACL_NAME_MAP.


Issues before/during Database Upgrade?

First of all the current preupgrd.sql does not warn you correctly if such ACLs exist. This fix gets added to the preupgrd.sql. But you'll need to download the most recent version from MOS Note 884522.1. The one from January 2015 does not have it yet. But this is addressed and will be implemented soon.

Here's an issue which happened to one of my very experienced colleagues from Oracle Consulting in an upgrade project:

"Customer had network ACLs defined and Privileges (resolve,connect) granted for several hosts to several DB users in

With the first DB, we observed the ACL renaming as you described it, but, much worse: 4 out of 9 privileges granted were completely gone away after the upgrade performed by DBUA (to We then were able to evaluate the missing privileges and re-grant them again. Warned by that, for the next databases to be upgraded, we copied all the content of the DBA_NETWORK_ACLS and DBA_NETWORK_ACL_PRIVILEGES to helper tables in order to be able to restore lost privileges (which was a good idea, as in one of the databases, only 87 out of 240 formerly existing privileges survived the upgrade)." 


Check for existing Network ACLs before the upgrade or get the most recent preupgrd.sql once it contains the check.

Preserve the existing network ACLs and privileges (DBA_NETWORK_ACLS and DBA_NETWORK_ACL_PRIVILEGES) in a intermediate staging table to have the possibility to restore them afterwards in case the automatic migration fails or does not happen.

If you encounter a situation where your Network ACLs don't get migrated correctly, disappear and/or don't exist in the mapping table DBA_ACL_NAME_MAP afterwards please open an SR and let Oracle Support check. There are known issues with mappings and migrations not done correctly (find some bugs below) so needs to be verified if you have hit a known issue or encountered a new one.

More Information?



Thursday Nov 19, 2015

Why you should remove APEX from the CDB$ROOT

Upgrade Blog posts about Oracle Application Express:

Oracle APEX (Application Express) is great piece of software. But it gets installed by default into the container database's CDB$ROOT unless you'd customized your CDB creation via scripts in Oracle See: 

on how to customize a Single/Multitenant Database with less options.

But that is not the topic I would like to write about. I came across an pitfall in the past days twice.

Think of having a local APEX (Application Express) application in a standalone database or already inside a PDB. You'd like to plug it into a CDB, regardless if this CDB is local or in the Oracle DBaaS Cloud. But your current APEX is on a lower version than the APEX inside the target CDB.

Let's assume you'd like to migrate this standalone database or PDB over into the cloud. But as soon as you plug it in - even though you'll have Oracle Database in both sites locally and in the cloud, you can't open your PDB in read/write mode. It will open RESTRICTED only.

Then you'll check PDB_PLUG_IN_VIOLATIONS and get a plug in error:

"APEX mismatch: PDB installed version CDB installed version" 

Reason is simply that an Oracle Database standard deployment will contain APEX 4.2.0 whereas the Oracle Cloud deployment in this scenario uses the more recent APEX version 5.0 already.

Having APEX installed into the CDB$ROOT was not a great idea. Actually it will cause you a lot of trouble and does not make much sense in the idea of Multitenant concept.

Oracle APEX Multitenant

I see why it has been done this way as not having APEX in the CDB$ROOT would have meant not having it in the PDB$SEED either - and all further provisioned PDBs would not have had APEX deployed by default. In this case every PDB would have required a separate APEX installation - but then you'd get the freedom of different APEX versions within the same Multitenant environment. And way more freedom during unplug/plug. But I'll elaborate this further down below.

Different APEX versions in Multitenant

First of all check your current APEX version with this query:


-------- ------------ -------

Find out in which container APEX is currently installed into:

SQL> select r.COMP_NAME, r.VERSION, c.NAME, c.CON_ID from CDB_REGISTRY r, V$CONTAINERS c where r.CON_ID=c.CON_ID and r.COMP_ID='APEX' order by CON_ID;

COMP_NAME                   VERSION   NAME      CON_ID
--------------------------- --------- --------- ------
Oracle Application Express  CDB$ROOT       1

Then choose the best solution for your environment to avoid trouble with APEX in a Multitenant environment.


Migrate a PDB with containing an APEX 4.2 deployment into another CDB with APEX 5.0 already installed in the CDB$ROOT container (the standard deployment in the Oracle DBaaS Cloud).

Two Solutions

Basically I see two potential solutions:

  1. Remove APEX from the CDB$ROOT before plug in your PDB with a different APEX version
  2. Upgrade your APEX installation in the PDB after plugging it into the CDB to match the CDB's APEX version

Solution 1 - Remove APEX from the CDB$ROOT 

I'd prefer Solution 1 as this will give you way more freedom. It will even allow you to have different APEX versions in the same Multitenant environment in different PDBs. But you'll have to do this steps right after creation of the container database - or before you worked with APEX in any of your PDBs as the following steps will remove APEX from all your PDBs!!!! If you already have APEX applications inside one of your PDBs you must export them before the APEX removal. Keep in mind that the "application export" facility in APEX 4 does not carry your image files automatically (APEX 5 is smarter).

Remove APEX from CDB$ROOT will remove it from all PDBs as well

The Oracle Documentation describes the path pretty straight forward. 

  1. Make sure to change into the local $ORACLE_HOME/apex directory first before starting SQL*Plus as otherwise the removal process won't work and error out - I'd assume that path variables are not carried on correctly. 
    cd $ORACLE_HOME/apex

  2. Connect to your CDB$ROOT:
    sqlplus / as sysdba

  3. Run the "Remove APEX from the CDB$ROOT" script:
    SQL> @apxremov_con.sql

  4. Check afterwards if APEX has been removed - also check for invalid objects. If necessary recompile. 
    In my tests two objects were INVALID after the removal but could be easily fixed
    (this part is not mentioned in the documentation):

    no rows selected

    SQL> select object_name, status from dba_objects where status='INVALID';

    OBJECT_NAME                      STATUS
    -------------------------------- -------------
    APEX_SPATIAL                     INVALID

    SQL> @?/rdbms/admin/utlrp.sql

    SQL> select object_name, status from dba_objects where status='INVALID';
    no rows selected

  5. Once you have done this your PDB containing the APEX application should not give you APEX errors anymore upon plugin as there's no mismatch anymore between CDB$ROOT's and the PDB's APEX.

  6. Just in the case - independently of my example - you'd like to install APEX now locally into a PDB then you'll have to use the apexins.sql script:

    cd $ORACLE_HOME/apex
    sqlplus / as sysdba
    SQL> alter session set container=PDB1;
    SQL> @apexins.sql SYSAUX SYSAUX TEMP /i/

    Be aware - this step may run a long time (in my VBox image it took over 22 minutes to complete).

    timing for: Complete Installation
    Elapsed: 00:22:16.29

    Check the existence of the component finally:

    SQL> select comp_id, status , con_id from cdb_registry where comp_id='APEX';

    --------- ------- -------
    APEX      VALID         3

Solution 2 - Upgrade APEX in the PDB after plugin

Even though I'd prefer solution 1 there may be some cases where you'll have to deal with Solution 2 and upgrade APEX after plugin. One simple reason could be that somebody uses APEX already in another PDB and you can't export and preserve it for later import - then you better don't follow Solution 1 then as it will force you to test your backup/restore strategy concept soon after ... 

  1. Run apexins.sql (from the APEX 5.0 installation - $ORACLE_HOME/apex) only in this particular PDB after plugin. You'll have to use

  2. The documentation
    may not be correct mentioning all parameters without the --p option. Jason Straub corrected it:

    host &OH_HOME/perl/bin/perl -I &OH_HOME/rdbms/admin &OH_HOME/rdbms/admin/ -b apexins -c '<PDB_name>' apexins_nocdb.sql --pSYSAUX --pSYSAUX --pTEMP --p/i/

    whereas &OH_HOME represents the full path to the Oracle home.

More Scenarios 

If you look at some of the potential scenarios you may see when trying to move PDBs around including APEX applications it is pretty obvious why having APEX only locally inside each PDB is a wise move. It will give you way more flexibility, less trouble, actually less upgrades (and APEX upgrades can take a while) - and simply less headache.

Assume that my CDB1 and CDB2 below are at the same database version - having different database versions will require upgrade/downgrade tasks in addition. 

APEX installed commonly within CDB$ROOT

  • CDB1 has APEX 4.2 in CDB$ROOT
    CDB2 has APEX 5.0 in CDB$ROOT
    • Unplug a PDB from CDB1 and want to plug it into CDB2 but you'll get an error in PDB_PLUG_IN_VIOLATIONS:
      “APEX mismatch: PDB installed version CDB installed version”
    • That is actually the simple case as you'd only have to upgrade APEX inside the PDB:
      host &OH_HOME/perl/bin/perl -I &OH_HOME/rdbms/admin &OH_HOME/rdbms/admin/ -b apexins -c '<PDB_name>' apexins_nocdb.sql --pSYSAUX --pSYSAUX --pTEMP --p/i/

  • CDB1 has APEX 5.0 in CDB$ROOT
    CDB2 has APEX 4.2 in CDB$ROOT
    • You unplug a PDB from CDB1 and want to plug it into CDB2 - but you can't actually plug in.
    • As APEX can't be downgraded to 4.2 in your PDB you'll have to upgrade APEX in the CDB2 to 5.0 first
    • Then you can plugin your PDB into CDB2

APEX installed locally within the PDB only

  • CDB1 has APEX in CDB$ROOT
    CDB2 has NO APEX in CDB$ROOT
    • Unplug a PDB with an APEX application from CDB1 and want to plug it into CDB2- fails
    • You will need to install APEX into CDB2's CDB$ROOT before being able to plug in the PDB
      • And it has to be the same version of APEX as used in CDB1

  • CDB1 has NO APEX in CDB$ROOT
    CDB2 has APEX  in CDB$ROOT
    • Unplug a PDB from CDB1 (having APEX locally in the PDB only) and want to plug it into CDB2 - works if ...
      • the PDBs local APEX version match the CDB2's common APEX version
      • If they don't match ...
        • PDB has APEX 4.2
          CDB2 has APEX 5.0
          Works, but you will need to upgrade APEX in the PDB after plugin
        • PDB has APEX 5.0
          CDB2 has APEX 4.2
          Fails, and you'll have to upgrade CDB2s common APEX 4.2 to 5.0 first before being able to plugin.

  • CDB1 has NO APEX in CDB$ROOT
    CDB2 has NO APEX  in CDB$ROOT
    • That is actually the best case as you don't have to care.
      • The only thing you will need to be aware of is that you'll need to patch your ?/apex home in case that PDB has a higher APEX version already than the one we ship by default 

More Information

You can find more information via these links:

And Finally ...

I'd recommend to NEVER have APEX in any CDB$ROOT. I see the advantage of having it as a new PDB will always have APEX provisioned with it. That is convenient, no doubt. But honestly if you really need APEX in most or all of your PDBs then create your own PDB$MASTER and provision from this one instead of using the PDB$SEED. In all other cases it's by far easier to install APEX inside the PDB when you really need it. Even with the penalty that it requires some extra 10 or more minutes until it is ready to go.

Given also the fact that APEX upgrade may take a while as well (see this blog post:  ) there's another advantage which personally I consider way more important:

Having APEX locally in the PDB only offers you way more freedom and flexibility. All the complicated scenarios come up only when either the source has no APEX in the CDB$ROOT (APEX locally in the PDB) but the target has any version (most likely a different one) or the target has no APEX in the CDB$ROOT but the source had it. And even more fun, both CDBs have APEX in the CDB$ROOT but at different versions.

This can be totally avoided by NEVER having APEX installed in your CDB$ROOT.

Which means also for the Oracle Cloud DBaaS databases:
Remove APEX from the CDB$ROOT and install it into your PDB before really starting up doing APEX stuff inside. APEX is such cool piece of software - and it's free - and powerful - and easy!!!

And (thanks to Jason again for this hint) if you look into the APEX 5.0 Installation Guide you'll find this tip:


Oracle recommends removing Oracle Application Express from the root container database for the majority of use cases, except for hosting companies or installations where all pluggable databases (PDBs) utilize Oracle Application Express and they all need to run the exact same release and patch set of Oracle Application Express. To learn more, see "Installing Application Express into Different PDBs."


Monday Nov 16, 2015

UPDATE: _rowsets_enabled in Oracle Database 12c

Last week I did post this entry with a strong recommendation to disable _rowsets_enabled in Oracle Database

Today I can give you an update, more insight information and better workarounds.

Credits go to our DWH and Optimizer people (thanks to Hermann, Angela, Nigel and Mohammed).

When is the problem happening?

When a hash join operation receives rowsets from its right input but then produces one row at a time as output. This explains why one of the bugs had as potential workaround hash_join_enabled=false (and please don't use this as a w/a!!!).

Different Workarounds 

  • Set
    event = "10055 trace name context forever, level 2097152"
    in your spfile. This will disable rowsets only for the specific situation where the problem happens.

    An important comment from Angela if you intend to set this event via an ALTER SESSION command:
    "Note that if the event is set with an alter session, it will not take effect unless the query or queries are recompiled, such as by changing the query text (by adding spaces or comments) or by flushing the shared pool."

  • Set
    in your spfile. But this will switch off the entire feature, not only the particular situation where the problem happens.

  • Apply the fix for
    (as of Nov 16, 2015 in regression testing and not available yet) as soon as it is available.

Thanks again to the Optimizer folks for their quick reaction!!!


Tuesday Nov 10, 2015

Switch off "_rowsets_enabled" in Oracle Database 12c

Please find a recent update here:



Twitter is a good thing. I get alerted on things I haven't seen before. And sometimes some things are more than interesting.

This one is actually proven by Jonathan Lewis - and you can read all the details in Jonathan's blog post here:

There seems to be a realistic chance to get wrong query results displayed (regardless of using SQL*Plus or a JDBC or any other client - see the comment by Stefan Koehler below Jonathan's posting) because of the row sets feature in Oracle 12.1 allowing faster initial processing of query results.

You'll find this in the query information (marked in bold red):

Column Projection Information (identified by operation id):
   1 - "K"."KONTO_ID"[NUMBER,22]
   4 - (#keys=1) "KP"."KONTO_FK"[NUMBER,22],
   5 - (rowset=256) "KP"."KONTOPOSITION_ID"[NUMBER,22],
   6 - (rowset=256) "KWP"."KONTOPOSITION_FK"[NUMBER,22],
   8 - "K"."KONTO_ID"[NUMBER,22] 

Roy did some analysis yesterday as well (and now our Optimizer Support Experts look into this case to check whether any other wrong query result bugs are related to this topic). Because there are some open WRONG RESULTS bugs in this area, some of which were filed within the past week, we'd recommend to switch this feature off at the moment.  For instance these bugs are related to this misbehavior:

Recommendation - Updated (Nov 15, 2015)

Please read the update blog post here:


Friday Nov 06, 2015

Oracle Database Release Status - MOS Note:742060.1

Almost every day I get at least one email by somebody asking things such as ...

  • What is the current status of Oracle 
  • Is Oracle Standard Edition One under Extended Support's treatment?
  • Do I get bug fixes for Oracle
  • And is it really true that I don't get bug fixes for Oracle anymore???

All valid questions - and all of them get answered within this reference note called:

Why am I writing this?

Simply because the Lifetime Support Policy Brochure only has now a link to a central MOS note added - but no explanatory text such as "Full Extended Support coverage will only apply to the terminal release". And the link is added in the right bottom corner underneath the table on (real) page 6 (the document's pagination doesn't count pages 1 and 2 as 1 and 2 for whatever reason). 

MOS Note:742060.1 has now an updated chart displaying clearly the Support Periods:

Oracle Release Chart

And a nice overview table clearly showing the Patching End Dates as well:

Oracle Patching End Dates for the Database

MOS Note:742060.1 is clearly THE REFERENCE in terms of questions such as:

  • How long will I get bug fixes for release X?
  • When is Premier Support ending for release Y?
  • Do I get Waived Extended Support for release Z?

Friday Oct 30, 2015

OOW 2015 - Upgrade Hundreds and Thousands

Uhh .. OOW15 is finally over.

Lots of work - tons of great input - and so many excellent discussions with customers, users and Oracle ACE's.

Just in case you'd like to download our slides please find the in the Slides Download Center to your right.

Thanks again - and hope to see you again next year!



Tuesday Oct 27, 2015

OOW 2015 - Upgrade and Migrate to Oracle 12c Talk - Live and Uncensored - Get the Slides

Thank You, Thank You, Thank You!!!

Roy and I were extremely happy yesterday as the room was full. Totally sold out. I've read on Twitter that some people wanted to go in and weren't allowed to join as the room capacity was reached.

If you want to get the few slides for our first talk:

And thanks again - you were an awesome audience! And we are looking forward to see you in one of our two other talks:.

  • Our 2nd talk will happen on Wednesday at 12:15pm (skip the unhealthy lunch).
    We'll contrast some nasty things with some very good and detailed customer examples included in it. Real world examples, no artificial lab exercises. Againuncensored (mostly <img src=" title=";-)" style="border: none;" /> ) and just from first hand experience.

    How to Upgrade Hundreds or Thousands of Databases in a Reasonable Amount of Time [CON8375]
    Mike Dietrich, Master Product Manager, Oracle
    Roy Swonger, Sr Director, Software Development, Oracle

    Wednesday, Oct 28, 12:15 p.m. | Moscone South—102
  • The 3rd talk of our group is the Data Pump  Performance Tips and Tricks talk delivered by Data Pump experts from Development.

    Deep Dive: More Oracle Data Pump Performance Tips and Tricks [CON8376]
    Dean Gagne, Consulting Member of Technical Staff, Oracle
    Jim Stenoish, Senior Director, Software Development, Oracle

    Thursday, Oct 29, 9:30 a.m. | Moscone South—305


Monday Oct 26, 2015

OOW 2015 - if you've missed our Upgrade Hands On Lab

Ready to kick off with the first of our four Hands-On-Labs at OOW15 at the Nikko Hotel. Currently it's calm before the storm  ...

OOW 2015

But just in case you didn't grab a seat at one of the labs then please come to our talk today (Monday!) at 1:30pm in Moscone South 102 as we'll show you the core parts of the lab - and you'll be able to download it later on from the blog and run it by yourself.

Download the lab via this link:


Oracle Database 12.2 - just if you weren't aware

News from the keynote on Sunday, Oct. 25, 2015 at OOW 2015:

Availability of Oracle Database 12.2 ...

So still a while to go ;-)


Friday Oct 23, 2015

OOW 2015 - Upgrade and Migration Talks

Oracle Open World 2015
will kick off in a day and a bit.
And still some work to do ;-)

A few things I would like to mention:

  • Our four HOLs are all overbooked already with many people on the waiting lists. You can always come by and wait in line at the Nikko Hotel's Golden Gate lab room as some people don't show up. But no guarantee. What I would recommend to you in case you are interested in the lab but didn't get a seat:

    Come to our talk instead on Monday at 1:30pm as Roy and I will demonstrate LIVE and UNCENSORED parts of the lab. Then you'll download it from the blog (find it in the Slides Download Center) and try it out by yourself afterwards: Hands On Lab Upgrade, Migrate, Consolidate to 12c

    Upgrade and Migrate to Oracle Database 12c: Live and Uncensored! [CON6777]
    Mike Dietrich, Master Product Manager, Oracle
    Roy Swonger, Sr Director, Software Development, Oracle

    Monday, Oct 26, 1:30 p.m. | Moscone South—102
  • Our 2nd talk will happen on Wednesday at 12:15pm (skip the unhealthy lunch).
    We'll contrast some nasty things with some very good and detailed customer examples included in it. Real world examples, no artificial lab exercises. Again uncensored (mostly ;-) ) and just from first hand experience.

    How to Upgrade Hundreds or Thousands of Databases in a Reasonable Amount of Time [CON8375]
    Mike Dietrich, Master Product Manager, Oracle
    Roy Swonger, Sr Director, Software Development, Oracle

    Wednesday, Oct 28, 12:15 p.m. | Moscone South—102
  • The 3rd talk of our group is the Data Pump  Performance Tips and Tricks talk delivered by Data Pump experts from Development.

    Deep Dive: More Oracle Data Pump Performance Tips and Tricks [CON8376]
    Dean Gagne, Consulting Member of Technical Staff, Oracle
    Jim Stenoish, Senior Director, Software Development, Oracle

    Thursday, Oct 29, 9:30 a.m. | Moscone South—305
  • And the 4th talk I'd like to highlight is the Database Upgrade 12c - Oracle Support talk from Support Architect Roderick Manalac.

    Oracle Database 12c Upgrade: Tools and Best Practices from Oracle Support [CON8664]
    Roderick Manalac, Architect - Database Support, Oracle
    Thursday, Oct 29, 12:00 p.m. | Moscone South—305


CU soon :-)


Thursday Oct 22, 2015

PSU (and CPU/SPU) October 2015 got released

October 21, 2015 - Oracle released the October 2015 SPU/CPU, PSU and BPs. 


For Oracle Database and Oracle Grid Infrastructure access the PSUs from here - if you have only a single instance database you can safely take the Combo patch as you'll get downtime anyways - but for customers running RAC you need to evaluate the OJVM component as this will incur downtime which the database-only patch does not require as it can be applied rolling.

Patch Set Updates

Document Description Rolling RAC Patch Download
Note:21555660.8 Oracle JavaVM Component Database PSU (Oct 2015) (OJVM PSU) No Patch:21555660
Note:21520444.8 Combo of OJVM PSU and DB PSU (Oct 2015) Part Patch:21520444

No patch found at the moment [Mike]
Note:21359755.8 (Oct 2015) Database Patch Set Update (DB PSU) Yes Patch:21359755

Grid Infrastructure

Document Description Rolling RAC Patch Download
Note:21523260.8 Combo of OJVM PSU and GI PSU (Oct 2015) Part Patch:21523260
Note:21523234.8 (Oct 2015) Grid Infrastructure Patch Set Update (GI PSU) Yes Patch:21523234

And be aware to patch your DBaaS Cloud databases as well - this is not done automatically ;-)



Tuesday Oct 20, 2015

Where do these large trace files come from in Oracle 12c?

Just had an observation about very large trace files on one of my customers I'm working with at the moment. When I write "very" I mean "VERY" as some grew over 10GB within a few hours.

Growth - Trace Files - (c) Mike Dietrich

The files contained a ton of such messages:

----- Cursor Obsoletion Dump sql_id=5p8a9d4017bq3 -----
Parent cursor obsoleted 1 time(s). maxchild=1024 basephd=00007FFB8AD45CB0 phd=00007FFB8AD45CB0

After doing a bit of research I came across this document and an explanation:

MOS Note:1955319.1;
Huge Trace Files Created Containing "----- Cursor Obsoletion Dump sql_id=%s -----"

Well, we introduced an Enhancement - via an unpublished bug (and I'd guess it is undocumented then) in Oracle Database to improve cursor sharing diagnostics by dumping information about an obsolete parent cursor and it's child cursors after the parent cursor has been obsoleted N times.

You can control this behavior by altering the value for:

alter system set "_kks_obsolete_dump_threshold" = 0;

Possible value range is 0..8 whereas 0 means: switch the obsolete cursor dump off completely, and other values (N) defined the number of invalidations after which the cursor will be dumped.

The default in Oracle Database is 1 meaning this will happen after every single invalidation

Just be aware that the underlying cursor sharing problem needs to be investigated always.


Saturday Oct 17, 2015

Extended Support Fee for Oracle waived until May 31, 2017 - Extended Support until Dec 2020

Friday, Oct 16, 2015, Oracle announced that the Extended Support for Oracle Database will be waived until May 31, 2017. After this period of Waived Extendend Support, Extended Support for Oracle Database will be offered until end of December 2020.

This information can be found here:

Something to mention:

  • There's no bug fixing support for Oracle Database or below available anymore
  • If you'll compare the effort to upgrade to Oracle Database to Oracle you'll have to do the exact same amount of work. tests etc - no difference
  • UPDATE [Oct 20, 2015]
    Now MOS Note:742060.1 has updated as well but only the text, not the graphic yet. Usually this will take another few extra days as the owner of the Note is not in charge of the graph's creation. Please be patient ;-)


Friday Oct 16, 2015

Ouch, this hurts: bug 20880215 - patch Oracle 12c


Just realized that my preivous blog post heading was misleading: it said "patch AFTER upgrade" which is misleading. You should apply this patch BEFORE you upgrade but of course to your new/future Oracle 12c home. If you hit the issue then apply the patch after upgrading to remedy it. Sorry for the confusion.

No updates for over a week? Sorry for that but too many workshops, swamped with OOW prep work - and a wonderful issue with the browser cache and the blog software putting all my new blog post work directly into /dev/null.

Thanks to Marcel Paul for highlighting this issue to me. I really benefit from such emails as I can learn a lot from those - and furthermore distribute information to many other tech folks as well.

Actually Marcel updated me as a follow up to me recent blog post:

describing an issue which will require to apply a patch before upgrade if you are not on Oracle or higher - and the below issue is related to this one but requires a patch AFTER upgrade, regardless what your source version was.


Marcel let me know about an issue they saw with their upgrade from Oracle to Oracle after the upgrade causing a core dump and potential table metadata corruption when you'll ADD a column to a table with a DEFAULT and ENABLE NOVALIDATE. This issue gets treated as bug 20880215 (ORA-7445 [QCSISCOLINFRO()+358] FOR ADD COLUMN WITH DEFAULT AND ENABLE NOVALIDATE)

Test Case

Very simple test case done by Marcel (thanks again!) - I could verify it within 30 seconds. 

create table dummy(code varchar2(5), text varchar2(30));
insert into dummy(code, text) values ('CD1','Hello World');
select * from dummy;
alter table dummy ADD condition varchar2(3) DEFAULT 'YES' not null enable novalidate;
select * from dummy;


First of all the client (in my case SQL*Plus) will disconnect with the meaningless ORA-3113. So lets have a look into the alert.log for more useful information:

Wed Oct 14 15:06:59 2015
Exception [type: SIGSEGV, Address not mapped to object] [ADDR:0x4] [PC:0xCDB0046, qcsIsColInFro()+358] [flags: 0x0, count: 1]
Errors in file /oradata/diag/rdbms/cdb2/CDB2/trace/CDB2_ora_2424.trc  (incident=3433) (PDBNAME=CDB$ROOT):
ORA-07445: exception encountered: core dump [qcsIsColInFro()+358] [SIGSEGV] [ADDR:0x4] [PC:0xCDB0046] [Address not mapped to object] []
Incident details in: /oradata/diag/rdbms/cdb2/CDB2/incident/incdir_3433/CDB2_ora_2424_i3433.trc

Use ADRCI or Support Workbench to package the incident.
See Note 411.1 at My Oracle Support for error and packaging details.

Wed Oct 14 15:07:08 2015
Dumping diagnostic data in directory=[cdmp_20151014150708], requested by (instance=1, osid=2424), summary=[incident=3433].

So we've got a core dump. And whatever we query now from the table involving the column "condition" we'll get the same error.


Apply the fix for bug 20880215 (ORA-7445 [QCSISCOLINFRO+358] FOR ADD COLUMN WITH DEFAULT AND ENABLE NOVALIDATE). You may have to request the fix for your platform if it hasn't been done yet. 

Further Information

A request for inclusion into the next Bundle Patches had been filed as well.


Tuesday Oct 06, 2015

New in Oracle 12c: _optimizer_gather_stats_on_load

Received an email from Roy last night with some performance issues a customer in the US encountered recently during their upgrade testing

One issue the customer encountered has to do with tons of parallel slaves creating a massive noise on the system when they are doing a CTAS (Create Table As Select) - and the same thing happens with an IAS (Insert Append Select).

What caused this change?

In this case the behavior change is well documented, even though not linked to the responsible underscore parameter. 

Quoting from the first paper: 

Online statistics gathering

In Oracle Database 12c, online statistics gathering “piggybacks” statistics gather as part of a direct-path data loading operation such as, create table as select (CTAS) and insert as select (IAS) operations. Gathering statistics as part of the data loading operation, means no additional full data scan is required to have statistics available immediately after the data is loaded.

The parameter controlling this change is not mentioned:

  • _optimizer_gather_stats_on_load

The default is TRUE since Oracle - the parameter or functionality did not exist before Oracle Database 12c.

Things to Know

The online stats gathering for IAS can happen only if the object you are loading data into is empty. You'll recognize the feature when you see a line saying OPTIMIZER STATISTICS GATHERING in the execution plan. Additionally you'll find STATS_ON_LOAD in the NOTES column of below query:


Consider now that first of all immediate stats gathering may not be desired as it will mean additional load to the system. Even though the feature has been designed to generate as little load as possible it's still doing something in the background. Hence there may be situations where you'd like to switch it off, e.g. with a hint:

insert /*+append NO_GATHER_OPTIMIZER_STATISTICS*/ into MYTAB select ...

And how about the number of parallel slaves creating the statistics? 

There's no easy answer to this based on the information I have at the moment - but I'd highly recommend this article about parallel execution in Oracle:


Friday Oct 02, 2015

OOW 2015 Sessions and Labs - Oracle Open World

OOW 2015OMG ... only a few weeks to go ... Oracle Open World 2015 in San Francisco is coming closer and closer ...

And this year will be really tough as we have a reduced number of people there - but more work to do as in previous years. 3 talks (2 for Upgrade, 1 for Data Pump), 4 labs (all in Nikko Hotel 15min walking distance from Moscone Center) - plus a good number of customer meetings already lined up. Plus the chance to meet so many great people ... and not to forget the Data Warehouse Global Leaders event at the Oracle HQ. 

I have that strange feeling that I will be VERY tired when I'll board the plane on Friday night heading back to Germany ... ;-)

Focus On Upgrades/Migrations

As the fantastic application we are using for the OOW content catalog doesn't allow me to link directly to a session Roy has built a Focus On document to guide you to some important talks around Upgrades and Migrations at OOW2015.for your convenience: 


Session ID


Start Time


CON6777 Upgrade and Migrate to Oracle Database 12c: Live and Uncensored!

Many customers now have database environments numbering in the hundreds or even thousands. This session addresses the challenge of maintaining technical currency of such an environment while also containing upgrade and migration costs at a reasonable level. Learn from Oracle Database upgrade experts about product features, options, tools, techniques, and services that can help you maintain control of your database environment. You will also see examples of how real customers are successfully meeting this challenge today.
October 26
at 13:30h
Moscone South—102
CON8375 How to Upgrade Hundreds or Thousands of Databases in a Reasonable Amount of Time

Many customers now have database environments numbering in the hundreds or even thousands. This session addresses the challenge of maintaining technical currency of such an environment while also containing upgrade and migration costs at a reasonable level. Learn from Oracle Database upgrade experts about product features, options, tools, techniques, and services that can help you maintain control of your database environment. You will also see examples of how real customers are successfully meeting this challenge today.
October 28
at 12:15h
Moscone South—102
CON8376 Deep Dive: More Oracle Data Pump Performance Tips and Tricks

The Oracle Data Pump development team is back with even more performance tips and tricks for DBAs! In this session, learn about Oracle Data Pump features, parameters, and patches—some added since the first patch set of Oracle Database 12c—that will improve performance and decrease overhead for Oracle Data Pump projects. Whether you are an Oracle Data Pump novice or already an expert, you are sure to learn something new in this session that will help you maximize the throughput of your export and import operations.
October 29
at 9:30h

Moscone South—305

HOL10348 Upgrade, Migrate, and Consolidate to Oracle Database 12c [HOL10438]

The Oracle Data Pump development team is back with even more performance tips and tricks for DBAs! In this session, learn about Oracle Data Pump features, parameters, and patches—some added since the first patch set of Oracle Database 12c—that will improve performance and decrease overhead for Oracle Data Pump projects. Whether you are an Oracle Data Pump novice or already an expert, you are sure to learn something new in this session that will help you maximize the throughput of your export and import operations.
Oct 26 at 11:00h
Oct 27 at 11:45h
Oct 28 at 13:15h
Oct 29 at 12:30h

Hotel Nikko - Golden Gate

Hope to see you at OOW 2015!


Tuesday Sep 29, 2015

No OS Authentication? datapatch will fail in every upgrade

Thanks to Daniel from SimCorp for bringing this to my attention:Patch
Actually, command line upgrades are affected as well,
if you do not use OS authentication. Apparently, datapatch
is not able to execute in non-OS authentication mode.
See MOS note 1635007.1. 


You are doing a command line upgrade to Oracle Database 12c with - and you don't use OS authentication allowing connections with "/ as sysdba" then won't be able to execute the SPU/PSU/BP related SQL commands as it will fail to connect to your database with an ORA-1017 (invalid username/password) error.


Bug 18361221 is fixed in Oracle 12.2 and got backported to and but not actually included in any bundles at the moment. Without this fix, datapatch will only connect with '/ as sysdba'. 

Either apply generic patch 18361221 to your destination Oracle Home or switch on OS authentication by setting:

temporarily in your sqlnet.ora for the duration of the upgrade only. See the documentation for further information about SQLNET.AUTHENTICATION_SERVICES. Or, of course, run -verbose after upgrading your database in any case ...

Further Information and Links:

Related Blog Posts


Monday Sep 21, 2015

DBUA displays wrong RMAN backup for restore - Oracle

If you are using the Database Upgrade Assistant (DBUA) to upgrade your database to Oracle Database be aware when you choose to potentially restore your database from a existing backup in case of an error during the upgrade.

First of all I would always stop DBUA and try the command line upgrade after fixing the issues instead of restoring the entire database. But this is a different story.

Anyhow, the most recent available backup to be displayed is most likely your newest one as the underlying query uses a MAX function - but leading to an incorrect (or unintended) result.

Ignore the fact that the screenshot is in German - the interesting part is the displayed time stamp for the most recent available backup:

DBUA Restore Backup

The customer who alerted me was wondering as his list of backups showed also backups from August and early September.

The query being used in DBUA to gather the most recent date; 

SELECT MAX (TO_CHAR (completion_time, 'DD-MON-YYYY HH24:MI:SS')) AS end_time FROM (SELECT completion_time FROM v$backup_set)

may give you this result: 31-JUL-2015 23:59:52 - even if you have newer backups taken in August and September. The TO_CHAR conversion will lead to the incorrect handling of the date as the MAX function won't deliver the most recent date but the alphabetical highest value of the conversion result. 

The query should be: 

SELECT MAX (completion_time) AS end_time
FROM (SELECT completion_time FROM v$backup_set)

to display the most recent full backup.

It will be fixed in the next release.
Credits go to Bernd Tuba from MM Warburg - thanks!!


Thursday Sep 17, 2015

SE2 - Some questions, some answers ...

Oracle Standard Edition SE2*** Updated on Nov 6  to reflect changes***

There were a lot of questions regarding Oracle Database Standard Edition SE2 in the past days.And you may find some things mentioned especially in the COMMENT section of the blog post from Sep 1, 2015.

And please find the official Oracle SE2 "brief" document here giving you a good overview on SE2:

I'll try to summarize some topics I'm able to answer by myself. And please don't expect me to assist with license or license migration questions - that is far beyond my scope or knowledge or responsibility, and you may please contact your Oracle sales person regarding these topics instead.

Please find all our articles about Oracle Database Standard Edition SE2:

Software and Support 

  • Q:
    How long will Premier Support offered for Oracle Database Standard Edition SE and SE1?
  • A:
    Premier Support for Oracle Database Standard Edition SE and SE1 will continue until Aug 31, 2016. After this date (as of Sep 1, 2016) Oracle SE/SE1 will enter Sustaining Support.
  • Q:
    Will there be Extended Support offered for Oracle Database Standard Edition SE and SE1?
  • A:
    No. Extended Support for 12.1 SE and SE1 is not offered. The Lifetime Support Policy document has been updated to reflect this.
  • Q:
    Is the extension of the Waived Extended Support and the Paid Extended Support for Oracle valid for SE and SE1 as well?
  • A:
    Yes, it is - there's actually no distinction (as far as I know) between support periods for SE, SE1 and EE.
  • Q:
    Are there plans to release Oracle SE/SE1?
  • A:
    Oracle Standard Edition will be offered as SE2 only.
  • Q:
    Is hard partitioning allowed with SE2?
  • A:
    Yes, it is as long as there are no more that 2 physical sockets in the server and you are using a supported hard partitioning software to bind a VM to a specific CPU. SE2 is not allowed to run on servers with more than 2 sockets.
    For an explanation and a list of supported hard partitioning technologies please see here:
  • Q:
    Is Oracle Multitenant available with SE2?
  • A:
    Oracle Multitenant is an Oracle Enterprise Edition only license. But you can have Oracle Single Tenant with many benefits meaning you'll have one pluggable database within one container database. Features such as remote cloning will be fully supported. See:
  • Q:
    Can we move PDB from SE2 Single Tenant to a EE Single/Multitenant database? 
  • A:
    Yes, of course - this is fully supported.

Database Installation and Patching

  • Q:
    Can I install Oracle Standard Edition SE2 into the existing home (in-place)?
  • A:
    Yes, this is possible even though I would never recommend to do this for the simple reason that wiping out your current home will increase the potential downtime and cause you plenty of extra work in case of fallback. If you still want to install for whatever reason into the existing home there's no change in handling to any other Oracle release since Oracle
  • Q:
    Which PSU should I apply on top of the releases Oracle Database Standard Edition SE2 installation?
  • A:
    Take the same PSU as you would take for an EE database - there's no difference and there won't be specific PSUs (or SPU/CPUs or BPs) released for SE2. Check out MOS Note:1683799.1 ( Patch Set - Availability and Known Issues) for the most recent recommended PSU
  • Q:
    Is RAC (Real Application Clusters) still included in SE2?
  • A:
    Yes it is - limited to 2 nodes, and each node must be a single-socket server. See above: there's the possibility to either remove a CPU physically - or hard partitioning with a supported virtualization solution such as OVM.
  • Q:
    I would like to use SE2 with RAC. Which Grid Infrastructure will I need to download?
  • A:
    When deploying a SE2 RAC Cluster please download the regular Oracle Grid Infrastructure (GI) packages from the official download locations (OTN, MOS, eDelivery). There's no separate download for an SE2 GI.
  • Q:
    Can I install/use SE2 on a 4-socket server?
  • A:
    No - SE2 is limited to be deployed on 2-socket servers only. And physically removing 2 CPUs from a 4-socket-machine does not satisfy the license agreement.
  • Q: 
    Can I deploy more than one SE2 database on a server?
  • A:
    Yes, of course you can.

Database Upgrade

  • Q:
    I want to upgrade from Oracle SE/SE1 to Oracle SE2. Is there any specific procedure or tool to use?
  • A:
    Upgrade works exactly as expected. There's no difference for SE2 compared to the upgrade procedure from Oracle EE to Oracle EE. 
  • Q:
    I would like to upgrade from Oracle SE/SE1 to Oracle EE. Is there any specific procedure or tool to use?
  • A:
    Upgrade is always the same procedure, regardless of SE, SE1, SE2 or EE. But if you'll convert from SE/1/2 to EE please follow the advises in MOS Note:2046103.1 (How to Convert Oracle Database 12c from Standard to Enterprise Edition ?)

Other topics

  • Q:
    Does the thread limitation in SE2 (16 in single instance mode, 8 per node in RAC mode) include background processes?
  • A:
    No, background processes such as LGWR or PMON are not included in this limitation.
  • Q:
    Is the thread limitation valid across all instances on the same server?
  • A:
    No, the limit is enforced per database instance and not per server.
  • Q:
    Does the thread limitation happen based on number of OS threads or CPU threads?
  • A:
    Actually the use of the term "threads" may be a bit misleading. Please have a look into the documentation about Instance Caging. That will explain how the thread limitation will be enforced. Views to monitor the resource usage are: V$RSRC_CONSUMER_GROUPV$RSRCMGRMETRIC and V$RSRCMGRMETRIC_HISTORY.
  • Q:
    Is there a core limitation for the hardware SE2 is installed on?
  • A:
    No, the box you'll use Oracle SE2 on can have as many cores as the CPUs offer. But there's a socket limitation of a maximum of 2 physical sockets. But the most modern CPUs can present 36 cores to SE2 on a 2-socket machine. 
  • Q:
    Can I disable Hyper Threading to present more "real" threads to the database?
  • A:
    Yes, this is possible but the effect may not be huge.


Wednesday Sep 16, 2015

Script: Is your database ready for Oracle GoldenGate?

Oracle GoldenGate can be a good addition to a lot of upgrade and migration projects to decrease the downtime to a bare minimum, or even zero in some cases.

But before you consider Oracle GoldenGate as THE solution to decrease your downtime you may evaluate if your database is ready for OGG. For this purpose you can download scripts from MyOracle Support (MOS) to check exactly this.

Complete Database Profile OGG readiness check for Classic Extract 

MOS Note:1298562.1:
GoldenGate database Complete Database Profile check script for Oracle DB (All Schemas) Classic Extract 

This script is intended to query all of the non default database users to identify current configuration and identify any unsupported data types or types that may need special considerations for Oracle GoldenGate in an Oracle environment.

Check OGG readiness for Schema Only

MOS Note: 1296168.1
Oracle GoldenGate database Schema Profile check script for Oracle DB

This script is intended to query the database by schema to identify current configuration and identify any unsupported data types or types that may need special considerations for Oracle GoldenGate in an Oracle environment. 

Difference and Execution 

The main difference between the two scripts is the amount of data being processed. The Schema Script is more targeted and therefore should return fewer items that need additional checking.

Log into sqlplus as sysdba and run the script:

SQL> @full-DB_CheckOracle_15092015.sql

SQL> @full-schemaCheckOracle_15092015.sql

Review the output.


Monday Sep 14, 2015

SQL Plan Management - Known Issues in Oracle

Our Support colleagues released the patch recommendation note for SQL Plan Management (SPM) for Oracle Database


SPM Note

In the unlikely event you'd like to upgrade to Oracle Database or (very very unlikely hopefully) please see these matching notes:


Some additional things to mention:

  • SPM is an Oracle Enterprise Edition feature at no extra cost
  • SPM is THE feature to ensure plan stability tackling changes such as (of course) upgrades and migrations
  • SPM has been improved a lot internally in Oracle Database
    • We now store entire plans instead of a large accumulation of hints in the SQL Management Base (SMB) in SYSAUX tablespace
    • The "Evolve" task does happen automatically (SYS_AUTO_SPM_EVOLVE_TASK) as part of the Automatic SQL Tuning Task 
  • You should always adjust the retention when starting to play with SQL Plan Management as the default retention of 53 weeks may lead to a too large LOB segment in SYSAUX tablespace (and LOB segments never shrink)
    • SQL> exec DBMS_SPM.CONFIGURE('plan_retention_weeks',5);
  • See the Oracle Database 12c documentation about SPM:



Thursday Sep 10, 2015

Don't get puzzled by "sqlpatch" messages during Upgrade

During my last Hands-On-Labs in Uruguay and Argentina I've had several people wondering about these messages below when running the command line upgrade with - sqlpatch

This (and another) message breaks the nicely structured format of the output. And as it ends with an "err" extension it looks to many people as if the upgrade had gotten an error,

But please don't feel disturbed. It's just messages from sqlpatch invocation - and the "err" extension is just pointing to an error file in case something has gone wrong.

In a future release such messages will be written to the logfiles only but not to the screen output anymore.


Wednesday Sep 09, 2015

Different Metrics for SPA (SQL Performance Analyzer)

I'm more the command line type of person. Once I've understand what's going on behind the curtains I certainly switch to the GUI-click-click tools. But in the case of Real Application Testing - even though the support via the OEM GUI is excellent - sometimes I prefer to run my procedures from the command line and check my reports in the browser.

Recently Thomas, a colleague from Oracle ACS Support, and I were asking ourselves about the different comparison metrics for the SQL Performance Analyzer reporting We did scan the documentation but we found only examples but no complete list. Then we did ask a colleague but thanks to OEM we got an incomplete list as well.

Finally Thomas dug it out - it's stored in the dictionary in the table V$SQLPA_METRIC

SQL> SELECT metric_name FROM v$sqlpa_metric;


9 rows selected.

What do you do with these metrics now?

You can use them in such a way:

set timing on

   execution_name=>'Compare workload Elapsed',
   execution_type=>'compare performance',
                     'execution_name2','TEST 11107 workload'),
   execution_desc=>'Compare 11107 Workload on 12102 Elapsed');

You can vary the elapsed_time in my example with the various comparison metrics mentioned in v$sqlpa_metric


Tuesday Sep 08, 2015

MOS Download for Oracle Database including SE2

Please find all our articles about Oracle Database Standard Edition SE2:


You have 3 options to download Oracle Database Enterprise Edition and Oracle Database Standard Edition SE2.

Regarding OTN and eDelivery nothing has been changed since Sep 1, 2015 when Oracle Database Standard Edition SE2 got published. But the download from MOS now has changed.

When you search in the under Patches and Updates tab ...

Patches And Updates - MOS

... and display the Latest Patch Sets ...

Latest Patch Sets - MOS

... check for instance for platform Linux x86-64bit ...

MOS - Linux

... then you'll wonder about the two patch numbers ...

Patch Numbers Oracle SE2

The only difference of 2.5 GB in size results from two more zip files included in the new patch number 2141921 ...

... you'll have to check the README button to find out what's hidden behind each file ...

Files 3 and 4 contain Oracle Database Standard Edition SE2.

So please don't get puzzled by the different patch numbers - the only real difference is the inclusion of SE2 into the download package but the included patches etc are exactly the same as in the previous patch number. 




Mike Dietrich - Oracle Mike Dietrich
Master Product Manager - Database Upgrade & Migrations - Oracle

Based in Germany. Interlink between customers/partners and the Upgrade Development. Running workshops between Arctic and Antartica. Assisting customers in their reference projects onsite and remotely. Connect via:

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