So, I have performed the migration on DEV - there were some problems with
it going out of memory, so I had to tweak it a bit (please have a look at
D1059, that is what I ended up using by hot-fixing on DEV).
There still is a slight problem, though - the migration of DEV took about
12 hours total, which is a bit unreasonable. Most of the time was spent in
`alembic/versions/dbfab576c81_change_schema_to_v2_0_step_2.py` lines 84-93
in D1059. The code takes about 5 seconds to change 1k results. That would
mean at least 15 hours of downtime on PROD, and that, I think is unreal...
And since I don't know how to make it faster (tips are most welcomed), I
suggest that we archive most of the data in STG/PROD before we go forward
with the migration. I'd make a complete backup, and deleted all but the
data from the last 3 months (or any other reasonable time span).
We can then populate an "archive" database, and migrate it on its own,
should we decide it is worth it (I don't think it is).
What do you think?
J.