Panos Kassianidis wrote:
and I would like to retrieve values recorded in the last 2 hours but
with an interval of 5 minutes, which means that my query should return
one tuple for every 5 tuples in the table and the value of this tuple
should be an average of 5 values.
Does anyone have any clue how I can make this query? I have though
about somehow grouping the tuples with group by and use the AVG
function but the tuples don't have anything in common to be grouped by.
You'll need to write an enhanced version of date_trunc() that can group
timestamps into arbitrary units, e.g.
my_date_trunc('... 12:34', 'm', 5) = '...12:30'
Then you can group by your new value.
--
Richard Huxton
Archonet Ltd
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TIP 9: In versions below 8.0, the planner will ignore your desire to
choose an index scan if your joining column's datatypes do not
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