Simon Krenger

Last week, I launched a new website for my csqlplus project.

What is csqlplus, you might ask. The csqlplus script is a wrapper for SQL*Plus and will allow you to query multiple databases at once, so bascially a SQL*Plus for clusters:

Often, Oracle database administrators need to run commands on multiple databases at once. With csqlplus, a wrapper for the sqlplus command, a DBA can quickly query multiple databases simultaneously.

Basically, csqlplus is a simple wrapper script to call sqlplus for all databases specified in a file.

You can download the script from the website www.csqlplus.org.

When working with the new multitenant architecture of Oracle 12c, one is often confronted with questions like “Ok, is this or that possible in the pluggable database? And where is that value stored?”. In this article, I want to show you where the parameters of the pluggable databases are stored. Hint: there is no SPFILE for a pluggable database!

Consider the following container database (CDB), named “cdb2”, with the following pluggable databases (PDBs). Using SQL*Plus, connected to the CDB, we can issue show pdbs to get a list of the PDBs and their status:

Recently I had to install SQL*Plus on a Linux host. In order to do so, I downloaded the appropriate Oracle Instant Client packages from the Oracle site. For my installation, I chose the ZIP files. After I unzipped the client and tried to run sqlplus, I go the following error:

simon@pandora instantclient_11_2$ ./sqlplus
./sqlplus: error while loading shared libraries: libsqlplus.so: cannot open shared object file: No such file or directory

Hmm. When I checked the directory with the sqlplus binary, the file libsqlplus.so was clearly there.

When you install the InstantClient binaries, you often want to use your existing TNSNAMES.ORA file containing all your databases. So how do you specify the location of your TNSNAMES.ORA file?

The Oracle website has the answer:

For Nagios, many, many Oracle plugins are available for checking database availability and performance. But if you just want to check if the instance is up and running (and not add more complexity), you can use the simple script provided here.

In an earlier post, I showed how to install SQL*Plus on Debian and based on that tutorial, I wrote a little shell script to query a database (I called it check_oracle_dual.sh):

In this article, I will describe the steps necessary to install Oracle SQL*Plus on a Debian host. I am using Debian 6.0.5 and will install the “Instant Client” package from Oracle (version 11.2.0.3). First, we will prepare the system for the installation, download the installation package, set all the necessary variables, start SQL*Plus and connect to an instance. So let’s get started…

Before we begin the package installation, we need to make sure the necessary prerequisite packages are installed. Oracle Instant Client requires the libaio package, so let’s install that:

Since most of our databases are not licensed with the Oracle Enterprise Manager Diagnostic Pack, we cannot use AWR (Automatic Workload Repository) and ADDM (Automatic Database Diagnostic Monitor). So we have to use the good old Oracle STATSPACK.

The goal of this article is to provide a quick reference for installing and maintaining STATSPACK for an Oracle database. It is based on the excellent “STATSPACK Survival Guide” of Akadia AG. If you need more information on STATSPACK, please refer to the Survival Guide or the Oracle documentation, since this article is only a really quick summary on how to install, configure and use STATSPACK.

Ok, here is a quick trick that I just found out about earlier this week. I am currently in an Oracle Database 11g: Administration 11 course and learn many new things about database administration.

One thing you will definitely encounter when working with Linux is that it is not possible to scroll back though your SQL*Plus history with the arrow keys. If you try to do so, the following happens:

SQL> select owner, count(1) from dba_tables group by owner;

OWNER				 COUNT(1)
------------------------------ ----------
[..]
SYS				      673
SIMON				       88


7 rows selected.

SQL> ^[[A     " - rest of line ignored.
SQL> command "
SQL> 

Argh! Some kind of wild character sequence appears on the command line. A quick search shows that this is a common problem. One thing that regularly happens is that you enter a SELECT statement that returns too many rows. Because the terminal buffer only contains a certain number of rows, your query disappears and you have to retype it.

In the last weeks, I had a few projects involving Oracle Advanced Replication and immediately stumbled upon the problem of not knowing which user and which instance was on which prompt. Instead of constantly issuing “SHOW USER” and “SELECT * FROM global_name“, I decided to add a few lines to my glogin.sql.

So before investing precious time, I fired up Google and found that other people also had the idea of changing the SQL*Plus prompt. I found the template for my own glogin.sql here and modified it so it fits my needs.

Note that my script does not display the GLOBAL_NAME of the databse, but only the INSTANCE_NAME read from v$instance. This means the prompt is usually a lot shorter:

repadmin@kdb3:SQL>

To change the prompt, append the following lines to your $ORACLE_HOME/sqlplus/admin/glogin.sql:

Today a colleague approached me and asked about the difference between the following two statements, because they return different results:

select count(*) from mytable;
select count(name) from mytable;