The migration has to rewrite the whole table, bigint needs 8 bytes so you have to make room for that.
I have done several such primary key migrations on tables with 500M+ records, they took anywhere from 30 to 120 minutes depending on the amount of columns and indexes. If you have foreign keys it can be even longer.
Edit: But there is another option which is logical replication. Change the type on your logical replica, then switch over. This way the downtime can be reduced to minutes.
I have done several such primary key migrations on tables with 500M+ records, they took anywhere from 30 to 120 minutes depending on the amount of columns and indexes. If you have foreign keys it can be even longer.
Edit: But there is another option which is logical replication. Change the type on your logical replica, then switch over. This way the downtime can be reduced to minutes.