How to avoid ORA-02153 when creating database links on (the unsupported way)

Disclaimer (wow, most of my recent posts start with a disclaimer, I guess it’s bad): this post explains an UNSUPPORTED workaround for an error enforced by recent Oracle security checks. You should never use it in production! Forewarned is forearmed.

Before Oracle Database, it was possible to create a database link using the following syntax:

It was possible to get the password hash by either selecting dbms_metadata.get_ddl for the database link or by querying directly the link$ table.

Starting with Oracle, Oracle is enforcing a check that prevents to use such syntax. Every newly created database link must have the password explicitly set.

This is clearly stated in the MOS note:

ORA-02153: Invalid VALUES Password String When Creating a Database Link Using BY VALUES With Obfuscated Password After Upgrade To (Doc ID 1905221.1)

This is seen as a security enhancement. In my opinion, it forces also to specify clear text passwords somewhere in the scripts that create the db links. (You do not create the db links by hand in sql*plus every time you need one.  Do you?)

The only exception is when using the expdp/impdp. If you expdp a schema, the dumpfile contains the password hash and the statement needed to recreate the database link (… identified by values ‘:1’), but Oracle only allows impdp to use such statement.

So, simple workaround, just create the database links on a dev/staging environment, export them using expdp and then provide your dba the dumpfile so he/she can import it and create the dblinks. Right? Not always.

There is one case where you really need of the old syntax.

  • You don’t know the password


  • You MUST change the database link name.

As you may know, there are no ways to change a database link name (even through impdp, there is no remap_dblink or anything like that).

E.g., you need to keep the db link and intend to use it for a check BUT you want to prevent the application from using it with the old name.

Because I believe that no problems exist that cannot be solved by my Trivadis’ colleagues, I’ve checked internally. A colleague came out with a dead simple (and unsupported) solution:

Insert/update$, flush the shared_pool.

Remember, use it at your own risk (or don’t use it at all) 😉



ORA-01882: timezone region not found while connecting to an EM12c target

After a recent upgrade to Enterprise Manager 12c, we noticed that the few Oracle Databases in release 10g were no more connectable:

ORA-01882On MOS there are a few notes about the error: ORA-00604: error occurred at recursive SQL level 1 ORA-01882: timezone region not found, the most relevant being Doc ID 1513536.1 and Doc ID 1934470.1.

The problem is due to the time zone table on the target database that doesn’t contain the timezone requested by the client. But who’s the client? In our case, all the target agents were correctly set to Europe/Zurich, but the timezone table of the target database contained it:

So what was causing the problem?

The upgrade process of the OMSes from to, without the presence of a specific TZ environment variable, set the OMS timezone to Europe/Vaduz. I figured it out after searching deep and large,  inside the WLS product properties:

Indeed, that timezone was not present in the timezone table version 4:

After setting explicitly the TZ to Europe/Zurich on the OMS servers and restarting the OMSes, everything was fine again.



My feedback after upgrading EM12c to

Today I’ve upgraded EM12c for a customer from the second-last version ( to the last one ( and the EM Repository from to

The upgrade path was not very easy: EM is not compatible with a repository and EM requires a mandatory patch for the repository if (or an upgrade to

So I’ve done:

  • upgrade of the repository from (in Data Guard configuration) to
  • upgrade of the EM from to
  • upgrade of the repository from to (in Data Guard configuration), from Solaris to Linux


In my case, I was particularly concerned about my customer’s EM topology:

  • two OMS in load balancing
  • console secured with a custom SSL certificate
  • a good amount of targets (more than 800 total targets, more than 500 targets with status)
  • a lot of jobs and custom reports
  • a big, shared central software library
  • many other small customizations: auth, groups, metrics, templates…

I will not bother with the actual execution steps, every installation may differ, I strongly recommend to read the upgrade documentation (I know, it’s HUGE 🙁 ).

Just to resume, the upgrade guide is here:

in my case I had to read carefully the chapters 3, 4, 5, 6 and appendixes G and K.

By following every step carefully, I had no problems at all and at the end everything was working correctly: all the targets up, the load balancing working in SSL as expected, the jobs restarted and ran successfully…

It has been incredible to see how many operations the OUI has done without raising a single error!!

Ok, it’s not just a Click Next Next Next Next installation, there are a lot of steps to do manually before and afterwards, but still… very good impression.

It took a little more than one hour to upgrade the first OMS (this also upgrades the EM repository) and a little less than 20 minutes to upgrade the second one.

Let a couple of hours for checking everything before, staging the binaries, taking backups/snapshots, creating restore points… and one hours more for upgrading the central agents and cleansing the old installations.

About upgrading/moving the repository, check this good post by Maaz AnjumMIGRATE ENTERPRISE MANAGER TO A PDB FROM A NON-CDB, even if you don’t plan to do it, it’s worth a read.



It’s confirmed. Standard Edition and Standard Edition One are dead.

The first voices came on July 3rd, 2015.

After many years of existence, Standard Edition and Standard Edition One will no longer be part of the Oracle Database Edition portfolio.

The short history

Standard Edition has been for longtime the “stepbrother” of Enterprise Edition, with less features, no options, but cheaper than EE. I can’t remember when SE has been released. It was before 2000s, I guess.

In 2003, Oracle released 10gR1. Many new features as been released for EE only, but:

– RAC as been included as part of Standard Edition

– Standard Edition One has been released, with an even lower price and “almost” the same features of Standard Edition.

For a few years, customers had the possibility to get huge savings (but many compromises) by choosing the cheaper editions.

SE ONE: just two sockets, but with today’s 18-core processors, the possibility to run Oracle on 36 cores (or more?) for less than 12k of licenses.

SE: up to four sockets and the possibility to run on either 72 core servers or RAC composed by a total of 72 cores (max 4 nodes) for less than the price of a 4-core Enterprise Edition deployement.

In 2014, for the first time, Oracle released a new Database version ( where  Standard Edition and SE One were not immediately available.

For months, customers asked: “When will the Oracle SE be available?”

Now the big announcement: SE and SE One will no longer exist. With, there’s a new Edition: Oracle Database Standard Edition 2.

You can find more information here:


Some highlights

– SE One will no longer exist

– SE is replaced by SE Two that has a limitation of 2 sockets

– SE Two still has RAC feature, with a maximum of two single-socket servers.

– Customers with SE on 4 socket nodes (or clusters) will need to migrate to 2 socket nodes (or clusters)

– Customers with SE One should definitely be prepared to spend some money to upgrade to SE Two, which comes at the same price of the old Standard Edition. ($17,500 per socket).

– the smallest amount of NUP licenses when licensing per named users has been increased to 10 (it was 5 with SE and SE One).

– Each SE2 Database can run max 16 user threads (in RAC, max 8 per instance). This is limited by the database Resource Manager. It does not prevent customers from using all the cores, in case they want to deploy many databases per server.


So, finally, less scalability for the same pricetag.

Other bloggers have already written about the behaviour of SE2. The best blog post is IMO from Franck Pachot.