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Brian Hess commented on CASSANDRA-11873:
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Being subtlety different on syntax is in some cases worse than being very
different. So, if we are thinking we will go with ISO 8601 format (an option
that could make sense - it is a widely recognized format and present in more
than a few systems (not just databases, I mean)) then we should make sure we
include the "P" and the "T".
While Postgres does support ISO 8601 formats (of course I bothered to read it),
in that format the highest resolution is seconds. There is a good reason to
want milliseconds and microseconds (and maybe nanoseconds). The standard
Postgres format support all of these (with the exception of nanoseconds, though
that addition to their format would be straightforward to understand). If you
want to shorten the Postgres format to save typing, what abbreviation do you
propose for "minute" and "month"?
I will certainly agree that the Oracle syntax is not user-friendly. I think
arguing it is desirable is a stretch.
I have a reservation on the Influx syntax here, though. Influx does not support
month or year. They only have up to week
(https://docs.influxdata.com/influxdb/v0.13/query_language/data_exploration/#relative-time).
So, it is not possible to say "now() - 2 months" or "now() - 1 year". To do 1
year, what would you do? "now() - 365d"? What about leap year? What about going
back one month?
In fact, this patch only had a subset of Influx's supported format. I don't see
a week unit. Moreover, Influx doesn't use "us", it uses just "u". So, our
proposed syntax isn't even consistent (in subtle ways) with Influx's format.
Let alone that Influx's format is incomplete (specifically, no support for
months and years).
Of the formats I've seen here, Postgres native format is the most user
friendly, and accomplishes the goals of durations for us. I'm (non-PMC,
non-binding) -1 on the currently proposed format from a
usability/product/developer POV.
> Add duration type
> -----------------
>
> Key: CASSANDRA-11873
> URL: https://issues.apache.org/jira/browse/CASSANDRA-11873
> Project: Cassandra
> Issue Type: Improvement
> Components: CQL
> Reporter: Benjamin Lerer
> Assignee: Benjamin Lerer
> Labels: client-impacting, doc-impacting
> Fix For: 3.x
>
>
> For CASSANDRA-11871 or to allow queries with {{WHERE}} clause like:
> {{... WHERE reading_time < now() - 2h}}, we need to support some duration
> type.
> In my opinion, it should be represented internally as a number of
> microseconds.
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