sql, config: incorrect handling of pre-21.1 zone configs #61316
Description
#57184 introduced two new zone config attributes num_voters and voter_constraints. This was achieved by introducing the following new fields to the zone config proto:
optional int32 num_voters
repeated ConstraintsConjunction voter_constraints
optional bool inherited_voter_constraints
The inherited_voter_constraints field helps to disambiguate an empty (but not inherited) voter_constraints against an inherited voter_constraints. However, ZoneConfig protos persisted in 20.2 will not contain these new fields. When such protos are unmarshalled by a 21.1 node, inherted_voter_constraints will default to false.
To reproduce:
roachprod create $CLUSTER -n 5;
roachprod stage $CLUSTER release v20.2.7;
roachprod start $CLUSTER --racks=5;
# set up a zone config hierarchy based on just the 20.2 fields
roachprod sql $CLUSTER:1 -- -e "create database db; use db; create table t ();"
roachprod sql $CLUSTER:1 -- -e "alter database db configure zone using num_replicas = 3, constraints = '{\"+rack=1\":1}';"
roachprod sql $CLUSTER:1 -- -e "use db; alter table t configure zone using constraints = '{\"+rack=1\":1}';"
# upgrade the cluster
roachprod stop $CLUSTER;
roachprod stage $CLUSTER cockroach
roachprod start $CLUSTER --racks=5;
roachprod sql $CLUSTER:1 -- -e "RESET CLUSTER SETTING cluster.preserve_downgrade_option;"
sleep 60;
# make the database level zone config use the new attributes
roachprod sql $CLUSTER:1 -- -e "alter database db configure zone using num_replicas = 3, num_voters = 3, voter_constraints = '{\"+rack=1\":1}';"
# at this point, the table should be inheriting the database level voter_constraints, but it won't.
roachprod sql $CLUSTER:1 -- -e "use db; show zone configuration for table t;"