sql: copy system.tenants separately to control the copied names

When we start the `TenantTwo` we want it to have `system` as its name from
the very beginning. To achieve this, instead of rewriting keys we use
KVWriter. `TenantTwo`'s name would become `system`, and `TenantOne`'s name
would be whatever is passed to `create_tenant` command (ideally, `main`).
Note, we are chaning this value for `TenantTwo`'s `tenants` table, not for
the `TenantOne`'s system table.

pkg/sql/catalog/bootstrap/initial_values.go

@@ -18,11 +18,16 @@ import (
 	"github.com/cockroachdb/cockroach/pkg/config/zonepb"
 	"github.com/cockroachdb/cockroach/pkg/keys"
 	"github.com/cockroachdb/cockroach/pkg/kv"
+	"github.com/cockroachdb/cockroach/pkg/multitenant/mtinfo"
+	"github.com/cockroachdb/cockroach/pkg/multitenant/mtinfopb"
 	"github.com/cockroachdb/cockroach/pkg/roachpb"
 	"github.com/cockroachdb/cockroach/pkg/sql/catalog"
 	"github.com/cockroachdb/cockroach/pkg/sql/isql"
 	"github.com/cockroachdb/cockroach/pkg/sql/sem/catconstants"
+	"github.com/cockroachdb/cockroach/pkg/sql/sem/tree"
+	"github.com/cockroachdb/cockroach/pkg/sql/sessiondata"
 	"github.com/cockroachdb/cockroach/pkg/util/log"
+	"github.com/cockroachdb/cockroach/pkg/util/protoutil"
 	"github.com/cockroachdb/errors"
 )
 
@@ -117,6 +122,13 @@ func copySystemTableKVs(
 	ret := make([]roachpb.KeyValue, 0)
 	sourceCodec := keys.SystemSQLCodec
 
+	if kvs, err := systemTenantTableKVs(
+		ctx, kvTxn, isqlTxn, targetCodec, descMap); err != nil {
+		return nil, err
+	} else {
+		ret = append(ret, kvs...)
+	}
+
 	tables := []catconstants.SystemTableName{
 		catconstants.ZonesTableName, // we need to filter out data for tables we don't need
 		catconstants.TenantSettingsTableName,
@@ -174,6 +186,99 @@ func copySystemTableKVs(
 	return ret, nil
 }
 
+func systemTenantTableKVs(
+	ctx context.Context,
+	kvTxn *kv.Txn,
+	isqlTxn isql.Txn,
+	targetCodec keys.SQLCodec,
+	descMap map[string]catalog.Descriptor,
+) ([]roachpb.KeyValue, error) {
+	ret := make([]roachpb.KeyValue, 0)
+
+	tenants, err := GetTenantRecords(ctx, isqlTxn)
+	const expectedTenantsCount = 2
+	if err != nil {
+		return nil, err
+	} else if len(tenants) < expectedTenantsCount {
+		return nil, errors.Errorf(
+			"unexpected tenants count: expected %d, found %d",
+			expectedTenantsCount, len(tenants))
+	}
+
+	tenantOne := tenants[0]
+	if tenantOne.ID != roachpb.TenantOne.ToUint64() {
+		return nil, errors.Errorf(
+			"expected first tenant with id %d", roachpb.TenantOne.ToUint64())
+	}
+	tenantTwo := tenants[1]
+	if tenantTwo.ID != roachpb.TenantTwo.ToUint64() {
+		return nil, errors.Errorf(
+			"expected second tenant with id %d", roachpb.TenantTwo.ToUint64())
+	}
+
+	tenantOne.Name = tenantTwo.Name
+	tenantTwo.Name = catconstants.SystemTenantName
+
+	desc := descMap[string(catconstants.TenantsTableName)]
+	tenantsTableWriter := MakeKVWriter(targetCodec, desc.(catalog.TableDescriptor))
+	for _, tenantInfo := range tenants {
+		info := tenantInfo.ProtoInfo
+		infoBytes, err := protoutil.Marshal(&info)
+		if err != nil {
+			panic(err)
+		}
+		kvs, err := tenantsTableWriter.RecordToKeyValues(
+			// ID
+			tree.NewDInt(tree.DInt(tenantInfo.ID)),
+			// active -- deprecated.
+			tree.MakeDBool(true),
+			// info.
+			// TODO(shubham): Deal with some extra data later
+			tree.NewDBytes(tree.DBytes(infoBytes)),
+			// name.
+			tree.NewDString(string(tenantInfo.Name)),
+			// data_state.
+			tree.NewDInt(tree.DInt(tenantInfo.DataState)),
+			// service_mode.
+			tree.NewDInt(tree.DInt(tenantInfo.ServiceMode)),
+		)
+		if err != nil {
+			panic(err)
+		}
+
+		ret = append(ret, kvs...)
+	}
+
+	return ret, nil
+}
+
+// GetTenantRecords
+//
+// TODO(shubham): use sql.GetTenantRecordByID instead. It's copied as it is to
+// avoid some dependency headache for the time being. GetTenantRecordByID
+// retrieves a tenant in system.tenants.
+func GetTenantRecords(ctx context.Context, txn isql.Txn) ([]*mtinfopb.TenantInfo, error) {
+	q := `SELECT id, info, name, data_state, service_mode FROM system.tenants WHERE data_state != $1 ORDER BY id`
+	var arg interface{} = mtinfopb.DataStateDrop
+
+	rows, err := txn.QueryBufferedEx(ctx, "get-tenants-info",
+		txn.KV(), sessiondata.NodeUserSessionDataOverride, q, arg)
+	if err != nil {
+		return nil, err
+	}
+
+	tenants := make([]*mtinfopb.TenantInfo, 0, len(rows))
+	for _, row := range rows {
+		_, info, err := mtinfo.GetTenantInfoFromSQLRow(row)
+		if err != nil {
+			return nil, err
+		}
+		tenants = append(tenants, info)
+	}
+
+	return tenants, nil
+}
+
 // hardCodedInitialValues defines an initialValuesFactoryFn using
 // hard-coded values.
 type hardCodedInitialValues struct {