Influxdb: count() doesn't support tag

[tongh-qtl]

It's diffrerent from mysql
I know we can use show tag values to do the same thing but we may query very more times

[jsternberg]

A current workaround for this is to trick the system using subqueries. You just need to choose a known field and do this:

SELECT count(distinct(host)) FROM (SELECT value, host FROM cpu)

Not as performant as an ideal solution, but it works.

[sebito91]

This would be awesome, to be honest :heart:

[tongh-qtl]

@jsternberg it works,thx
we may make the tag be a redundancy field.it may waste some storage but the performance may be good

[jcmcken]

This would be extremely useful. I often have a need to visualize the number of rows that match certain criteria (e.g. in Grafana). I'm using the workaround suggested by @jsternberg , but it would be nice if this were baked into a real feature of the language.

[to-masz]

SHOW TAG VALUES CARDINALITY FROM memcached WITH KEY = "host" WHERE environment =~ /^$country$/

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This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

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