Negative timestamps are now supported. We also now refuse two
nanoseconds that are at the edge of the minimum time window. One of the
nanoseconds we do not accept is because we need MinInt64 to be used for
some internal comparisons in the TSM engine and it was causing an
underflow when we subtracted one from the minimum time. The second is so
we can have one minimum time that signifies the default minimum that
nobody can write to (so we can implicitly rewrite the timestamp on
aggregate queries) but still use the explicit timestamp if it is given
to us by the user. We aren't able to tell the difference between if the
user provided it or if it was implicit without those values being
different.
If the default minimum time is used with an aggregate query, we rewrite
the time to be the epoch for backwards compatibility since we believe
that's more important than supporting that extra nanosecond.
The highest time represented by a nanosecond needs to be used for an
exclusive range, so the maximum time needs to be one less than the
possible maximum number of nanoseconds representable by an int64 so that
we don't lose a point at that one time.
Previously worked in the open source version because the timestamp used
for finding a shard would be truncated by the retention policy so the
lookup time didn't run into this edge case because it didn't rest on the
truncation boundary. Since that point didn't really belong in that shard
group and was placed there by mistake, it's best to fix this bug since
the timestamp used to create the shard group should be capable of
retrieving it.
Jonathan A. Sternberg
Edd Robinson
Justin Nuß
Nathaniel Cook