Csaba Ringhofer created IMPALA-7365:
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Summary: Cache local timezone at startup
Key: IMPALA-7365
URL: https://issues.apache.org/jira/browse/IMPALA-7365
Project: IMPALA
Issue Type: Improvement
Components: Backend
Reporter: Csaba Ringhofer
Since IMPALA-3307, the coordinator checks the local timezone when starting a
query and sends this timezone to the executors. This means that if the system's
timezone is changed, it will not effect running queries, but new queries will
use the new timezone. Before IMPALA-3307, glibc was used for utc<->localtime
conversion, which was also affected by system's timezone, which means that
changing the timezone could affect a running query.
I think that it would be better to save the timezone at startup, and never look
at the system's timezone again. This would simplify some logic during query
startup and save a few system calls.
Note that some backend tests rely on the current behavior (see class
ScopedTimeZoneOverride) by setting environment variable $TZ. These tests will
need a new way to set the local timezone inside Impala.
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