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Cake day: June 15th, 2023

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  • Some satellites and rovers have used Radioisotope Thermoelectric Generators (RTGs), which are very different from a nuclear reactor. They use polonium-210, which generates heat, and that heat is converted to electricity with thermocouples. They are low power and inefficient.

    To my knowledge no satellite, with an RTG, has ever used ion propulsion. Few interplanetary satellites have ever even used ion thrusters. Dawn, Hayabusa, and Deep Space 1 are the only I can think of, and they all used solar arrays.

    Ion thrusters are super efficient, but produce extremely small amounts of thrust. They aren’t practical for getting large spacecraft to Mars. These proposed nuclear engines produce large thrust while have efficiency somewhere between regular chemical propulsion and ion propulsion.







  • Don’t delete from the local_user table. You only need to delete from the person table, the rest of the tables will be updated automatically and user count will update automatically.

    Edit: The below command will delete all unverified users. NOTE: If you do not have email verification turned on then all users are unverified, therefore all users will be deleted. It also appears with v18 when you enable email verification all existing users remain unverified.

    This is a destructive command, use at your own risk and don’t go fucking with the database if you don’t have backups.

    DELETE FROM person WHERE local = 'true' AND id IN (SELECT person_id FROM local_user WHERE email_verified = 'false');

    In the parenthesis you can add your AND to only select unverified accounts of a certain age.


  • Yes, person table is top level. Delete from person table and it cascades down and deletes from other tables. User count also automatically updates. Just be careful because person table also contains federated users. There is a “local” column to determine if they are local users or not.

    I had about 6k bot accounts, but they were all unverified, so I just deleted all local unverified accounts from the person table.

    Just don’t go messing with the database without backups. My host supports snapshots so I did a quick snapshot before messing with anything.


  • What I ended up doing is getting the person_ids, from the local_user table, that had verified emails. Since my instance literally only has 4 real users I then just deleted all the rows in the person table that were local users and weren’t the 4 real users. It took almost 2 hours to run but it worked. User count automatically updated and corresponding rows in all the other tables were automatically deleted.

    This is the command for getting person_ids of verified users:

    SELECT person_id FROM local_user WHERE email_verified = 'true';

    Then to delete all the local users, except for those with verified emails:

    DELETE FROM person WHERE local = 'true' AND id NOT IN (<ID1>,<ID2>,<ID3>);

    Unfortunately, this isn’t really helpful for anyone with lots of real users. Unless a SQL wizard knows how to do this, making a python script that queries all the person_ids of unverified users then deletes those from the person table is probably easiest.

    I’ll copy this to the Matrix room too since it might help admins there.