TZ environment variable

This topic details how to set or change the TZ environment variable and update your tzdata package.

This topic details how to set or change the TZ environment variable and update your tzdata package. If this variable is not set, then the installer reports this issue with the identifier: S0305.

Before installing Vertica, update the tzdata package for your system and set the default time zone for your database administrator account by specifying the TZ environmental variable. If your database administrator is being created by the install_vertica script, then set the TZ variable after you have installed Vertica.

Update tzdata package

The tzdata package is a public-domain time zone database that is pre-installed on most Linux systems. The tzdata package is updated periodically for time-zone changes across the world. You should update to the latest tzdata package before installing or updating Vertica.

Update your tzdata package with the following command:

RedHat based systems: yum update tzdata
Debian and Ubuntu systems: apt-get install tzdata

Setting the default time zone

When a client receives the result set of a SQL query, all rows contain data adjusted, if necessary, to the same time zone. That time zone is the default time zone of the initiator node unless the client explicitly overrides it using the SQL SET TIME ZONE command described in the SQL Reference Manual. The default time zone of any node is controlled by the TZ environment variable. If TZ is undefined, the operating system time zone.

Important

The TZ variable must be set to the same value on all nodes in the cluster.

If your operating system timezone is not set to the desired timezone of the database then make sure that the Linux environment variable TZ is set to the desired value on all cluster hosts.

The installer returns a warning if the TZ variable is not set. If your operating system timezone is appropriate for your database, then the operating system timezone is used and the warning can be safely ignored.

Setting the time zone on a host

Important

If you explicitly set the TZ environment variable at a command line before you start the Administration tools, the current setting will not take effect. The Administration Tools uses SSH to start copies on the other nodes, so each time SSH is used, the TZ variable for the startup command is reset. TZ must be set in the .profile or .bashrc files on all nodes in the cluster to take affect properly.

You can set the time zone several different ways, depending on the Linux distribution or the system administrator’s preferences.

To set the system time zone on Red Hat and SUSE Linux systems, edit:
```
/etc/sysconfig/clock
```
To set the TZ variable, edit, /etc/profile, or /home/dbadmin/.bashrc or /home/dbadmin/.bash_profile and add the following line (for example, for the US Eastern Time Zone):
```
export TZ="America/New_York"
```
For details on which timezone names are recognized by Vertica, see the appendix: Using time zones with Vertica.