Andrey Elenskiy created HBASE-21476:
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Summary: Support for nanosecond timestamps
Key: HBASE-21476
URL: https://issues.apache.org/jira/browse/HBASE-21476
Project: HBase
Issue Type: New Feature
Affects Versions: 2.1.1
Reporter: Andrey Elenskiy
Assignee: Andrey Elenskiy
Attachments: nanosecond_timestamps_v1.patch
Introducing a new table attribute "NANOSECOND_TIMESTAMPS" to tell HBase to
handle timestamps with nanosecond precision. This is useful for applications
that timestamp updates at the source with nanoseconds and still want features
like column family TTL and "hbase.hstore.time.to.purge.deletes" to work.
The attribute should be specified either on new tables or on existing tables
which have timestamps only with nanosecond precision. There's no migration from
milliseconds to nanoseconds for already existing tables. We could add this
migration as part of compaction if you think that would be useful, but that
would obviously make the change more complex.
I've added a new EnvironmentEdge method "currentTimeNano()" that uses
[java.time.Instant|https://docs.oracle.com/javase/8/docs/api/java/time/Instant.html]
to get time in nanoseconds which means it will only work with Java 8. The idea
is to gradually replace all places where "EnvironmentEdge.currentTime()" is
used to have HBase working purely with nanoseconds (which is a prerequisite for
HBASE-14070). Also, I've refactored ScanInfo and PartitionedMobCompactor to
expect TableDescriptor as an argument which makes code a little cleaner and
easier to extend.
Couple more points:
- column family TTL (specified in seconds) and
"hbase.hstore.time.to.purge.deletes" (specified in milliseconds) options don't
need to be changed, those are adjusted automatically.
- Per cell TTL needs to be scaled by clients accordingly after
"NANOSECOND_TIMESTAMPS" table attribute is specified.
Looking for everyone's feedback to know if that's a worthwhile direction. Will
add more comprehensive tests in a later patch.
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