Fix PsdmTimeBasedWeatherValueFactory

[johanneshiry]

The column names of the PsdmTimeBasedWeatherValueFactory are currently invalid.

• time -> time
• coordinate -> coordinateid
• diffuseirradiation -> diffuseirradiance
• directirradiation -> directirradiance
• winddirection -> winddirection
• windvelocity -> windvelocity
• temperature -> temperature

Furthermore the datum column of theIconTimeBasedWeatherValueFactory might be renamed to time as well. (considering #175)

Furthermore, Psdm� should be renamed to Cosmo.

[ckittl]

As of discussion today: The factory does not reflect the actual scheme in the weather database. Therefore, either the factory has to be altered or at the same time the scheme of the data base.

An argument for changing the data scheme is, that InfluxDB requires the time information to be called time. On the other hand, not changing the scheme, would not lead to breaking other applications.

Decision:

• Alter the scheme for the COSMO model within the data base, as this kind of is legacy data as well.
• Rename PsdmTimeBaseWeatherValueFactory to CosmoTimeBasedWeatherValueFactory
• Alter the scheme of ICON weather data as well (datum -> time, coordinate -> coordinateid; cf. Adapt date column name DWDWeatherTools#1) -- change the column name here as well

[ckittl]

Even more issues than expected...

• For some sources, the actual column names within the data base or file are needed. However, within the factories only the
  "iron case" names of the fields (neither of the known cases, all small letters, no underscores or hyphens) are apparent. These approaches are out there:
  • CouchbaseWeatherSource takes name of coordinate column from constructor -> possibly inconsistent to what the factory expects
  • InfluxDbWeatherSource takes the iron case field name from factory -> query does not work if the column is called coordinate_id
  • SqlWeatherSource queries meta data of table, "irons" the column name and checks for a match against the factory
• Field names in Couchbase (the actual source) are iron and not snake case as in other sources -> can it be harmonized?
  • Yes, there is no naming convention for JSON keys, snake case would be fine (cf. Stackoverflow discussion and JSON API Docs and the ECMA Standard 404 (no, it can be found))

Some reasoning about the next steps:

• Building of queries / way of determining the column name across sources shall be harmonized
• Currently all supported technologies support snake case, however, this is not necessarily the case for future technologies
  • Column name is determined by technology (case) and data scheme ("case less" value)
• The "case less" value of the column name should be invariant (therefore, the harmonization of data schemes)
• Holding the "case less" value in a way, that allow for technology specific transfer between different cases, e.g. in snake case, within the factories

@johanneshiry We had several discussion about this, would you mind to have one more? ^^

[ckittl]

Breaking down the above discussion to actual tasks:

• Adaption of COSMO column scheme in code
  • targeted in: Change scheme of COSMO weather data #321
• Adapt COMSO column scheme in all existing sources (files, database, ...)
• Adapt ICON column scheme in code
  • targeted in: Adapt column scheme of ICON weather data #329
• Adapt ICON column scheme in all existing sources (files, database, ...)
• SqlWeatherSource determines column name by querying the meta scheme
  • Check where this is actually used
  • Try to get rid of that implementation and use fixed column name convention instead
  • Moved to Rethink column name determination in SQL source #514
• Change Couchbase column names from flat to snake case
  • Moved to Couchbase column names in snake case #516
• Reflect the changes from here in DWDWeatherTools aka. check and create issues there