Mentat

The steps to migrate are as follows:

1. Stop and disable Mentat
    $ sudo systemctl stop warden_filer_cesnet_receiver.service
    $ sudo mentat-controller.py --command stop
    $ sudo mentat-controller.py --command disable

2. Stop Apache
    $ sudo systemctl stop apache2

### There can be no DB writes beyond this point as we are about to drop indices ensuring data integrity!

3. psql mentat_events
    DROP INDEX events_detecttime_idx;
    DROP INDEX events_combined_idx;
    DROP INDEX events_cesnet_storagetime_idx;
    DROP INDEX events_cesnet_eventseverity_idx;
    ALTER TABLE events DROP CONSTRAINT events_pkey;
    VACUUM FREEZE;
    CHECKPOINT;

4. Stop postgresql
    $ sudo systemctl stop postgresql

5. Install PostgreSQL 12
    $ sudo apt-get update
    $ sudo apt-get install postgresql-12 postgresql-12-ip4r postgresql-server-dev-12 postgresql-client-12

6. Migration
    $ sudo pg_lsclusters
    Ver Cluster Port Status Owner    Data directory              Log file
    11  main    5432 online postgres /var/lib/postgresql/11/main /var/log/postgresql/postgresql-11-main.log
    12  main    5433 online postgres /var/lib/postgresql/12/main /var/log/postgresql/postgresql-12-main.log

    $ sudo systemctl stop postgresql

    $ sudo pg_dropcluster 12 main

    $ sudo pg_lsclusters
    Ver Cluster Port Status Owner    Data directory              Log file
    11  main    5432 down   postgres /var/lib/postgresql/11/main /var/log/postgresql/postgresql-11-main.log

    # This will require *temporarily* setting wal_level to 'logical' (in postgresql.conf) - it is set to 'minimal' if you followed configuration advice from docs
    # Alternatively one can ommit the --link parameter, but that requires free space for a 1:1 copy and of course also takes much longer
    $ sudo pg_upgradecluster --method=upgrade --link 11 main

    $ sudo pg_dropcluster 11 main

7. Remove PostgreSQL 11
    $ sudo apt-get remove --purge postgresql-11 postgresql-client-11 postgresql-server-dev-11 postgresql-11-ip4r postgresql-9.4 postgresql-9.5 postgresql-9.6 postgresql-10

8. Start PostgreSQL
    $ sudo systemctl start postgresql

9. Indices
    REINDEX DATABASE mentat_events;
    ALTER TABLE events ADD PRIMARY KEY (id);
    CREATE INDEX IF NOT EXISTS events_detecttime_idx ON events USING BTREE (detecttime);
    CREATE INDEX IF NOT EXISTS events_cesnet_storagetime_idx ON events USING BTREE (cesnet_storagetime);
    CREATE INDEX IF NOT EXISTS events_cesnet_eventseverity_idx ON events USING BTREE (cesnet_eventseverity) WHERE cesnet_eventseverity IS NOT NULL;
    CREATE INDEX IF NOT EXISTS events_combined_idx ON events USING GIN (category, node_name, protocol, source_port, target_port, source_type, target_type, node_type, cesnet_resolvedabuses, cesnet_inspectionerrors);
    CHECKPOINT;
    ANALYZE;

10. Start Mentat & Apache
    $ sudo mentat-controller.py --command enable
    $ sudo mentat-controller.py --command start
    $ sudo systemctl start apache2
    $ sudo systemctl start warden_filer_cesnet_receiver.service

1. What are the actual performance impacts of the upgrade.

Radko, could you please add SHORT conclusion/observation?

TLDR conclusion:
A speedup is observable in sequential scan queries (i.e. IP address search) of up to 10%. We attribute this to JIT compiler making the <ip> && ANY({source,target}_ip) more efficient (as it should per documentation).