ok my guess here was, since pg_class is updated every now and then with stats, it might require some lock while adding the data.so if it were bloated, that would block the planner to get the estimates , and hence delay the query at whole.but that was a wild guess.
--pg_class not lockedpostgres@db:~$ time psql -c 'select * from pg_stat_database;' >/dev/nullreal 0m0.016suser 0m0.003ssys 0m0.000s-- pg_class locked and the query completed when tx it unlockspostgres@db:~$ time psql -c 'select * from pg_stat_database;' >/dev/nullreal 0m7.269suser 0m0.003ssys 0m0.000s
pgsql-general by date:
Соглашаюсь с условиями обработки персональных данных
