Customizing Time Zones

Starting in CDH 6.1 / 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 managed as impalad safety valves in Cloudera Manager.

    • --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:
  1. 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
  2. Build timezone tools: 
    cd tz
make TOPDIR=tzdata install
  3. 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
  4. Create zip archive: 
    pushd ./tzdata/etc
zip -r zoneinfo.zip zoneinfo
popd
  5. Copy the time zone database to HDFS: 
    hdfs dfs -mkdir -p /tzdb/latest
hdfs dfs -copyFromLocal ./tzdata/etc/zoneinfo.zip /tzdb/latest
  6. Set the --hdfs_zone_info_zip startup flag to /tzdb/latest/zoneinfo.zip as an impalad safety valve.
  7. Perform a full restart of Impala service.

Configuring custom time zone aliases:

  1. 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
  2. Copy the config file to HDFS: 
    hdfs dfs -mkdir -p /tzdb
hdfs dfs -copyFromLocal tzalias.conf /tzdb
  3. Set the --hdfs_zone_alias_conf startup flag to /tzdb/tzalias.conf as an impalad safety valve.
  4. Perform a full restart of Impala service.

Added in: CDH 6.1 / Impala 3.1