Annotation Query Format
An annotation is an event that is overlaid on top of graphs. The query can have up to four columns per row, the time column is mandatory. Annotation rendering is expensive so it is important to limit the number of rows returned.

- column with alias: time for the annotation event time. Use epoch time or any native date data type.
- column with alias: timeend for the annotation event time-end. Use epoch time or any native date data type.
- column with alias: text for the annotation text
- column with alias: tags for annotation tags. This is a comma separated string of tags e.g. 'tag1,tag2'


Macros:
- $__time(column) -> column as "time"
- $__timeEpoch -> extract(epoch from column) as "time"
- $__timeFilter(column) -> column BETWEEN '2017-04-21T05:01:17Z' AND '2017-04-21T05:01:17Z'
- $__unixEpochFilter(column) ->  column >= 1492750877 AND column <= 1492750877
- $__unixEpochNanoFilter(column) ->  column >= 1494410783152415214 AND column <= 1494497183142514872

Or build your own conditionals using these macros which just return the values:
- $__timeFrom() ->  '2017-04-21T05:01:17Z'
- $__timeTo() ->  '2017-04-21T05:01:17Z'
- $__unixEpochFrom() ->  1492750877
- $__unixEpochTo() ->  1492750877
- $__unixEpochNanoFrom() ->  1494410783152415214
- $__unixEpochNanoTo() ->  1494497183142514872