I want to determine the maximum value per day including past and future. The data are forecast values. They also include the entire current day and the following day. But a query without a WHERE clause only returns results up to the current time.
This is the query so far:
SELECT max("Prognose_Wh") FROM "Wetterprognose" group by time(1d)
The result provides the maximum values per day in the past, including the maximum value of the current day, but only up to now(). Today's maximum value is incorrect because a higher value is reached later this day. The following day, which is also contained in the requested data, is missing in the result.
How can I create a query in influxql that returns results from the past as well as data from the future?
Related
API in question: https://api.slack.com/methods/team.accessLogs
The maximum page is 100 and the maximum records per page(count) is 1000 so total 100,000 records could potentially be returned. Since there is no way to limit the starting date for the accessLog, the results will continue to grow as more unique user/IP/useragent combinations are used until it reaches the limit at which point it wouldn't be possible to return all records. Is this correct?
Also, the documentation does not specify how the results are ordered?
You have mentioned correctly that typically you can fetch 100,000 records.
But there is a way to limit the starting date.
before argument in api lets you set the time before which you want the records.
https://api.slack.com/methods/team.accessLogs#arg_before
The records are fetched in reverse chronological order i.e. latest record first, and by default, the value of before argument is 'now'.
After fetching first 100,000 records,
set before argument value as "date_last" value from the last record.
(keep in mind that before argument is inclusive of the value provided, therefore the last record will be repeated. To avoid it you can reduce "date_last" value by 1 )
Heading ##CALL ga.timetree.single({time: 1463659567468, create: true})
https://github.com/graphaware/neo4j-timetree
https://graphaware.com/neo4j/2014/08/20/graphaware-neo4j-timetree.html
The above link says that time is in long format YYYYMMDDHHmmss. But the time parameter doesn't make any sense and random nodes are getting generated in neo4j. enter image description here
What does the time parameter hold and what is the meaning of it?
The time parameter is a millisecond timestamp, or milliseconds elapsed since the UNIX epoch, which is an extremely common means of storing time-related data, you can find this in use in nearly every digital system.
The timestamp cited here represents "2016-05-19 12:06:07". The timetree built starts from a root (this is a modeling convenience), and then its child is the year (2016) followed by the month (5), then the date of the month (19). Looks like it didn't automatically create any nodes for time resolutions beyond that.
Keep in mind that now that Neo4j has native temporal values that you can use in Cypher and store as properties (as well as index), time trees are going to be less useful, as you can always do index lookups on indexed temporal properties.
There are still some cases where time trees can still be very useful, however, such as when you're searching for events that happened within some unit of time that disregards its parent units...such as finding events that happened on Mondays regardless of month, or on Januaries regardless of year, and so forth.
Is there a way to check and see if a time is between a time duration in Crystal Report? Our application has a field, let’s say, called StopTime but stored in integer format. It has the value of 0 at midnight, 60 at 1 am, … , 12x60= 720 at noon.
There is a need for me to create an input parameter with type Time which allows a range value so that user could select to view records within a certain time in the day.
My question is how do I check the value of the field again the input parameter in the record selection formula? I have tried
cast({StopTime}/60 as time) in {?TimeDuration}
but I got the error “There is an error in the formula. Do you want to save it anyway?”
I have also tried
{StopTime}/60 in {?TimeDuration}
and still got the error.
The only way to get around this error is declaring the parameter TimeDuration as Number that accepts a range. However, if possible, it is better to use the type of Time as I can foresee user issues with Number range when a time range is actually needed.
Your field {StopTime} is a number representing a number of minutes, and so must be cast to a time. In Crystal Syntax this is achieved using the CTime function which takes a parameter of a number in days. Therefore you must divide the number of minutes by 1440 to get it in to days. The following will do what you need.
ctime({StopTime}/1440) in {?TimeDuration}
I have an InfluxDB measurement which includes a field that holds either 0 or 1.
How do I find the longest unbroken run of a given value?
Imagine that the field represents whether the sun is up or not, and I have a year's worth of data. I would like the query which finds the longest unbroken run of 1's, which would represent the longest day of the year and return me something like "23rd June 5am to 23rd June 9pm". (I'm in the northern hemisphere, and totally made those times up, but hopefully you get the idea.)
I don't think this can be done with InfluxQL. In many RDBMS, it's possible to do similar operations in a single SQL query using window functions and grouping.
I've experimented a few ways, but as of v1.3 I believe InfluxQL is just not expressive enough for this task. Limitations include:
No window functions (although some functions exhibit similar behaviour, e.g. DIFFERENCE, DERIVATIVE).
time cannot be manipulated like an ordinary tag or field value. For example, it's not possible to take the FIRST(time) of a group of measurements.
Can only GROUP BY time or tag, not by field value (or derived value from a subquery result). Additionally, when grouped by time, only group interval timestamps are returned by selector functions.
Can only ORDER BY time.
The best way to do this is therefore at the application level.
Edit: for the record, the closest I can get is to use ELAPSED to find the longest gap(s) between subsequent 0 values. This might work for you if your data model is a specific shape and data comes in at regular intervals:
SELECT TOP(elapsed, N) AS elapsed FROM (SELECT ELAPSED(field) FROM measurement WHERE field != 1)
Returns e.g. for N = 1:
time elapsed
---- -------
2000 500
However, there is no guarantee that there is a value of 1 in the gap. Use FIRST to retrieve the first measurement with field == 1 within the gap, or nothing if there are none:
SELECT FIRST(field) FROM measurement WHERE field = 1 AND time < 2000 and time > (2000 - 500)
Returns e.g.:
time first
---- -----
1000 1
Therefore the longest run of 1 values is from 1000 -> 2000.
Background
I have a ror application which is continuously recording and showing on a web site real time sensor data. Then I have a table called sensors which has unique list of all sensors and stores latest values.
I also have another table histories which dumps all the sensor values ever received for each sensor.
So the relation is "sensor has many histories" , the time_stamp col records the creation time stamp.
Not all sensors update at same interval or frequency.
Problem
Now I want to take a input time stamp from user, a date and time in past, and show what the sensors were showing at that time. For example say i want to see what all sensors looked like at 2 PM yesterday, once i have this time stamp from user, how do i retrieve one sensors value closest to input time stamp from the history table.
I am looking to add a method in Sensor model, which will take time_stamp as argument, and retrive the value closest to input time_stamp from the history table.
What is they simplest way to write this Active record query?
Thanks
Shaunak
Just sort the histories according to the difference between the passed timestamp and the history timestamp (absolute value so it can go in either direction), and return the top result (that's the one with the smallest difference).
sensor.histories.order("ABS(time_stamp - #{params[:time_stamp].to_i})").first
Note that for this query I am assuming you are using MySQL (because I'm using a MySQL method ABS) and I am also assuming that the time_stamp field is stored as unix timestamp and the user input likewise. If the database storage or input is in a different format, you'll have to use different date arithmetic functions. See http://dev.mysql.com/doc/refman/5.5/en/date-and-time-functions.html for details. Or if you are not using MySQL, see the docs for the database you are using.
Also note that I am using .to_i to sanitize my data for the query. If your data is in a different format, you may need to sanitize it a different way.
To make this more efficient, limit it to time_spans within the maximum possible range. If sensors take data every 10 minutes or more frequently (never less than 10 minutes apart between readings), then a range of greater than 10 minutes on each side will do. Something like below. Here, 600 = 10 (minutes) * 60 (seconds):
sensor.histories.where("time_stamp >= ? AND time_stamp <= ?", params[:time_stamp].to_i - 600, params[:time_stamp].to_i + 600).order("ABS(time_stamp - #{params[:time_stamp].to_i})").first
It is simple to convert this to a model method:
class Sensor < ActiveRecord::Base
def history_at(time_stamp)
self.histories.where("time_stamp >= ? AND time_stamp <= ?", time_stamp.to_i - 600, time_stamp.to_i + 600).order("ABS(time_stamp - #{time_stamp.to_i})").first
end
end