You got the time?

A question came up about timezone handling in SAP HANA.

As you might know SAP HANA offers functions to deal with local time as well as with UTC based time and provides the means to convert between those two.

But how does SAP HANA knows what time zones exist, what their offsets are and how get these information updated once the time zones change (and yes, they do change quite often as can be seen here: International Date Line – Wikipedia, the free encyclopedia)?

SAP HANA can draw these information from two sources:

1. Built in default values. These are hard coded, unfortunately undocumented values, that are used when no other information is available.

2. Time zone data stored in the TZ* tables in schema SYSTEM (and only there).

SAP note 1791342 – Time Zone Support in HANA explains this in more detail.

Concerning the current timezone: this is taken from the LINUX environment of the user that starts the indexserver if I’m not mistaken.

This setting, that has to be the same on every node in a scale out setup, can be reviewed in system table M_HOST_INFORMATION.

select * from M_HOST_INFORMATION where upper(KEY) like '%TIMEZONE%'

HOST  |KEY            |VALUE

ld9506|timezone_offset|3600

ld9506|timezone_name  |CET

There you go, now you know.

– Lars