What you need to consider - regardless of using node context, flow context, join nodes etc is...
If you gather all the values into one object, when do you write it to DB?
I can guarantee you all 50 items will not update at the same time so you will be writing necessary/unchanged values to the DB in a wide table.
Wouldn't it be better to generate a long table vs wide table?
e.g...
| timestamp | topic | value |
|---|---|---|
| 123456789 | topic1 | 77.3 |
| 123456789 | topic2 | 73.2 |
| 123456792 | topic7 | 2.76 |
| 123456792 | topic4 | 7.01 |
this would negate the need to gather all values into an object & any future data will fit without modification to the database.
