Customizing Time Zones

Starting in Impala 3.1, you can customize the time zone definitions used in Impala.

By default, Impala uses the OS’s time zone database located in /usr/share/zoneinfo. This directory contains the IANA timezone database in a compiled binary format. The contents of the zoneinfo directory is controlled by the OS’s package manager.
Use the following start-up flags to customize the time zone definitions.
- ‑‑hdfs_zone_info_zip: This flag allows Impala administrators to specify a custom timezone database. The flag should be set to a shared (not necessarily HDFS) path that points to a zip archive of a custom IANA timezone database. The timezone database is expected to be in a compiled binary format. If the startup flag is set, Impala will use the specified timezone database instead of the default /usr/share/zoneinfo database. The timezone db upgrade process is described in detail below.
- ‑‑hdfs_zone_alias_conf: This flag allows Impala administrators to specify definitions for custom timezone aliases. The flag should be set to a shared (not necessarily HDFS) path that specifies a config file containing custom timezone alias definitions. This config file can be used as a workaround for users who want to keep using their legacy timezone names. Configuring custom aliases is described in detail below.

Upgrading custom IANA time zone database:

Download latest IANA time zone database distribution:
```
git clone https://github.com/eggert/tz
```
Alternatively, download a specific tzdb version from:
```
 https://www.iana.org/time-zones/repository
```
Build timezone tools:
```
cd tz
make TOPDIR=tzdata install
```

Generate the compiled binary time zone database:

./zic -d ./tzdata/etc/zoneinfo africa antarctica asia australasia backward backzone etcetera europe factory northamerica pacificnew southamerica systemv

Create zip archive:

pushd ./tzdata/etc
zip -r zoneinfo.zip zoneinfo
popd

Copy the time zone database to HDFS:

hdfs dfs -mkdir -p /tzdb/latest
hdfs dfs -copyFromLocal ./tzdata/etc/zoneinfo.zip /tzdb/latest

Set the ‑‑hdfs_zone_info_zip startup flag to /tzdb/latest/zoneinfo.zip as an impalad safety valve.
Perform a full restart of Impala service.

Create a tzalias.conf config file that contains time zone alias definitions formatted as ALIAS

DEFINITION. For example:

#
# Define aliases for existing timezone names:
#
Universal Coordinated Time = UTC
Mideast/Riyadh89 = Asia/Riyadh
PDT = America/Los_Angeles
#
# Define aliases as UTC offsets in seconds:
#
GMT-01:00 = 3600
GMT+01:00 = -3600

Copy the config file to HDFS:

hdfs dfs -mkdir -p /tzdb
hdfs dfs -copyFromLocal tzalias.conf /tzdb

Set the ‑‑hdfs_zone_alias_conf startup flag to /tzdb/tzalias.conf as an impalad safety valve.
Perform a full restart of Impala service.