Hi Joshua,
Thank you for pointing this out. The sentence "The timestamp reflects the
first time the field value appears in the data" is from a previous version
and shouldn't be in the documentation. In version 1.2, DISTINCT() returns
epoch 0 unless you specify a lower bound on the time range. We're actually
in the midst of reworking the entire functions page so I've added that to
the GitHub issue
<https://github.com/influxdata/docs.influxdata.com/issues/757>.
Again, thanks for letting us know. Apologies for the confusion - we promise
to get that fixed and improve that page!
Regan
On Thu, Feb 2, 2017 at 3:47 PM, <j...@clarkpdx.com> wrote:
> Hello,
> I'm using Influx to keep track of customer pass usage at a resort. Every
> time a customer scans their pass at a gate, I add their customer ID, pass
> type, and time to the db.
>
> I want to know the first time a unique customer scans in a 24h period
> (i.e. if that customer showed up that day), which will let me plot arrival
> times of each customer. The distinct function appeared perfect for this.
> The documentation gives this example:
>
>
> Select the unique field values in the level description field:
> > SELECT DISTINCT("level description") FROM "h2o_feet"
> name: h2o_feet
> --------------
> time distinct
> 1970-01-01T00:00:00Z between 6 and 9 feet
> 1970-01-01T00:00:00Z below 3 feet
> 1970-01-01T00:00:00Z between 3 and 6 feet
> 1970-01-01T00:00:00Z at or greater than 9 feet
>
> The response shows that level description has four distinct field values.
> The timestamp reflects the first time the field value appears in the data.
>
> If the timestamp indeed reflected the first time the field value appeared
> in the data, I would be set. However, on the very next line, the
> documentation notes this:
>
> Note: Aggregation functions return epoch 0 (1970-01-01T00:00:00Z) as the
> timestamp unless you specify a lower bound on the time range. Then they
> return the lower bound as the timestamp.
>
> This appears to state the exact opposite. The queries I've written all
> return epoch 0 as the timestamp. I was wondering if this is just a mistake
> in the documentation, or if there is some way to have DISTINCT (or some
> other function?) return the timestamp of the first distinct record in some
> time range.
>
> Thanks for helping me understand the distinct function,
> Joshua
>
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