I have made flow where I store data into a InfluxDB database.
I have the following problem:
When the machine stops running, the downtime starts. I insert the start time to the database. (see picture)
When the downtime is finished (and the machine starts running) I want to add the finish timestamp to the last row. And I will also change the category from pending to "undefined". (so I can define it later)
I tried a lot but don't get the right result to add data to an existing row.
Is there anyone out here to help me?
If you want to change an existing line you have to rewrite it, so find the line you want to overwrite (or keep the time value from it when you write it) and then you can write that record (with the timestamp you saved) and it will overwrite the previous record for that time.
You mean a measurement with three columns. A measurement is the equivalent of a table in a conventional database.
Influxdb is a time series database, so every record should be a time and what happened at that time. Are you storing other stuff in influx as well? If not then it may be that you would be better using, for example, sqlite or postgresql or something similar.
If you do want to store this in influx then I suggest for the start and finish times have fields time, state and category, where state is running or stopped and category can be whatever is required. Then when the machine starts you write a record with state "running" and when it stops you write a record with state "stopped". It doesn't really fit well with the influx model though, I think if I were doing it I would use a different databsase for the part of the problem.
In influx, time is effectively the id, however you can have multiple records for the same time provided they have different tag combinations. To understand that sentence you would need to know about influx fields and tags and the differences between them.
Yes, massive. There is also mariadb and MySQL to consider.
It is not a matter of preference, it is a matter of choosing the best one for the application. Since I have no idea about yours it is difficult to say. For example whether you are going to have tens of milliions of records eventually, with a thousand users accessing it concurrently, or tens of records with only a few users at a time.
I think probably some googling would be a good idea. I expect you can find articles discussing the differences for different applications.