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Take a COPY out of SQLcl’s book

As the world continues to get smaller, it makes sense for all databases to be defined to handle more than just US7ASCII, which is why the default characterset for all recent versions of the Oracle database is AL32UTF8. In that way, we can handle the various challenges when it comes to languages other than english.


SQL> create table t ( x varchar2(30 char));

Table created.

SQL> insert into t values ('안녕미미 99~12900원 시즌오프 원피');

1 row created.

But lets see what happens when we copy that data using some legacy facilities in SQL Plus.

No risk to activate Active Data Guard by mistake with SQL Developer SQLcl

If you have a Data Guard configuration without the Active Data Guard license, you can:

  • apply the redo to keep the physical standby synchronized
  • or open the database read-only to query it

but not at the same time.

Risk with sqlplus “startup”

Being opened READ ONLY WITH APPLY requires the Active Data Guard option. But that this may happen by mistake. For example, in sqlplus you just type “startup”, instead of “startup mount”. The standby database is opened read-only. Then the Data Guard broker (with state APPLY-ON) starts MRP and the primary database records that you are using Active Data Guard. And then DBA_FEATURE_USAGE_STATISTICS flags the usage of: “Active Data Guard — Real-Time Query on Physical Standby”. And the LMS auditors will count the option.

The ways to prevent it are unsupported:

Generate your Oracle Secure External Password Store wallet from your tnsnames.ora

Want to connect passwordless with SQLcl to your databases from a single location? Here is a script that creates the Secure External Password Store wallet credentials for each service declared in the tnsnames, as well as shell aliases for it (as bash does autocompletion). The idea is to put everything (wallet, sqlcl,…) in one single directory that you must protect of course because read access to the files is sufficient to connect to your databases.

Download the latest SQLcl from:

SQLcl Downloads

And install the Oracle Client if you do not have it already:

Oracle Instant Client Downloads

Now here is my script that:

SQLcl connect target depends on previous connection

I thought it was a bug for two reasons: first, because I don’t like that my connect destination depends on the context, and then because it is a different behavior than in SQL*Plus. But finally, it is the correct behavior, and the 100% compatibility with SQL*Plus is expected only when SET CLASSIC=ON. And as I was surprised, and I think it can be dangerous, here is a blog post about it. Basically, be very careful if you are connected with a service name and you want to connect locally.

Basically, if you attended my demo about ‘From Transportable Tablespaces to Pluggable Databases’, where I switch between different instances you may have seen that I had to run ‘connect / as sysdba’ two times because the first one failed with invalid username/password

SQL> connect scott/tiger@//localhost/PDB1
Connected.
...
SQL> connect / as sysdba
USER =
URL = jdbc:oracle:oci8:@//localhost/PDB1

SQLcl on Bash on Ubuntu on Windows

I’m running my laptop on Windows, which may sound weird, but Linux is unfortunately not an option when you exchange Microsoft Word documents, manage your e-mails and calendar with Outlook and present with Powerpoint using dual screen (I want to share on the beamer only the slides or demo screen, not my whole desktop). However, I have 3 ways to enjoy GNU/Linux: Cygwin to operate on my laptop, VirtualBox to run Linux hosts, and Cloud services when free trials are available.

Now that Windows 10 has a Linux subsystem, I’ll try it to see if I still need Cygwin.
In a summary, I’ll still use Cygwin, but may prefer this Linux subsystem to run SQLcl, the SQL Developer command line, from my laptop.

Don’t forget the COPY command in SQL*Plus (and SQLcl)

One of the developers asked me to copy a small table from Live to Dev. In situations like this, my first thought is to use the SQL*Plus COPY command. By the way, this command is also available in SQLcl.

It’s super-easy and has been around forever. Provided you can live with the data type restrictions, it’s a lot less hassle than expdp/impdp, even with the NETWORK_LINK option.