cannot drop zone from group, although there's no any partition in the zone

[HarrisChu]

2.6.0 branch.

1. create space on a group with 3 replicas and 4 zones.
2. balance remove data {all host in a zone}
3. drop zone {zone} from group

expected result:

1. as all partitions are removed from zone, the zone can be dropped.

actual result:

1. Conflict error

(root@nebula) [s2]> desc group g1
+------+
| Zone |
+------+
| "z1" |
+------+
| "z2" |
+------+
| "z3" |
+------+
| "z4" |
+------+
Got 4 rows (time spent 656/6543 us)

Thu, 14 Oct 2021 11:32:55 CST

(root@nebula) [(none)]> create space s2(replica_factor=3, vid_type=int, partition_num=4) on g1
Execution succeeded (time spent 1011/12510 us)

Thu, 14 Oct 2021 11:29:33 CST

(root@nebula) [(none)]> use s2
Execution succeeded (time spent 692/11503 us)

Thu, 14 Oct 2021 11:29:36 CST

(root@nebula) [s2]> show parts
+--------------+-----------------------------------------------------------------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+-------+
| Partition ID | Leader                                                                      | Peers                                                                                                                                                                                                                             | Losts |
+--------------+-----------------------------------------------------------------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+-------+
| 1            | "cbrpnm-storaged-4.cbrpnm-storaged-headless.default.svc.cluster.local:9779" | "cbrpnm-storaged-6.cbrpnm-storaged-headless.default.svc.cluster.local:9779, cbrpnm-storaged-4.cbrpnm-storaged-headless.default.svc.cluster.local:9779, cbrpnm-storaged-0.cbrpnm-storaged-headless.default.svc.cluster.local:9779" | ""    |
+--------------+-----------------------------------------------------------------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+-------+
| 2            | "cbrpnm-storaged-5.cbrpnm-storaged-headless.default.svc.cluster.local:9779" | "cbrpnm-storaged-5.cbrpnm-storaged-headless.default.svc.cluster.local:9779, cbrpnm-storaged-4.cbrpnm-storaged-headless.default.svc.cluster.local:9779, cbrpnm-storaged-3.cbrpnm-storaged-headless.default.svc.cluster.local:9779" | ""    |
+--------------+-----------------------------------------------------------------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+-------+
| 3            | "cbrpnm-storaged-6.cbrpnm-storaged-headless.default.svc.cluster.local:9779" | "cbrpnm-storaged-6.cbrpnm-storaged-headless.default.svc.cluster.local:9779, cbrpnm-storaged-1.cbrpnm-storaged-headless.default.svc.cluster.local:9779, cbrpnm-storaged-3.cbrpnm-storaged-headless.default.svc.cluster.local:9779" | ""    |
+--------------+-----------------------------------------------------------------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+-------+
| 4            | "cbrpnm-storaged-2.cbrpnm-storaged-headless.default.svc.cluster.local:9779" | "cbrpnm-storaged-4.cbrpnm-storaged-headless.default.svc.cluster.local:9779, cbrpnm-storaged-2.cbrpnm-storaged-headless.default.svc.cluster.local:9779, cbrpnm-storaged-3.cbrpnm-storaged-headless.default.svc.cluster.local:9779" | ""    |
+--------------+-----------------------------------------------------------------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+-------+
Got 4 rows (time spent 952/11188 us)

Thu, 14 Oct 2021 11:29:37 CST

(root@nebula) [s2]>  balance data remove "cbrpnm-storaged-0.cbrpnm-storaged-headless.default.svc.cluster.local":9779,"cbrpnm-storaged-1.cbrpnm-storaged-headless.default.svc.cluster.local":9779,"cbrpnm-storaged-2.cbrpnm-storaged-headless.default.svc.cluster.local":9779
+------------+
| ID         |
+------------+
| 1634182321 |
+------------+
Got 1 rows (time spent 1734/12795 us)

(root@nebula) [s2]> balance data 1634182321
+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------+-------------+
| balanceId, spaceId:partId, src->dst                                                                                                                                        | status      |
+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------+-------------+
| "[1634182321, 15:1, cbrpnm-storaged-0.cbrpnm-storaged-headless.default.svc.cluster.local:9779->cbrpnm-storaged-5.cbrpnm-storaged-headless.default.svc.cluster.local:9779]" | "SUCCEEDED" |
+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------+-------------+
| "[1634182321, 15:3, cbrpnm-storaged-1.cbrpnm-storaged-headless.default.svc.cluster.local:9779->cbrpnm-storaged-5.cbrpnm-storaged-headless.default.svc.cluster.local:9779]" | "SUCCEEDED" |
+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------+-------------+
| "[1634182321, 15:4, cbrpnm-storaged-2.cbrpnm-storaged-headless.default.svc.cluster.local:9779->cbrpnm-storaged-6.cbrpnm-storaged-headless.default.svc.cluster.local:9779]" | "SUCCEEDED" |
+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------+-------------+
| "Total:3, Succeeded:3, Failed:0, In Progress:0, Invalid:0"                                                                                                                 | 100.0       |
+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------+-------------+
Got 4 rows (time spent 701/6520 us)

Thu, 14 Oct 2021 11:30:27 CST

(root@nebula) [s2]> show parts
+--------------+-----------------------------------------------------------------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+-------+
| Partition ID | Leader                                                                      | Peers                                                                                                                                                                                                                             | Losts |
+--------------+-----------------------------------------------------------------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+-------+
| 1            | "cbrpnm-storaged-4.cbrpnm-storaged-headless.default.svc.cluster.local:9779" | "cbrpnm-storaged-6.cbrpnm-storaged-headless.default.svc.cluster.local:9779, cbrpnm-storaged-4.cbrpnm-storaged-headless.default.svc.cluster.local:9779, cbrpnm-storaged-5.cbrpnm-storaged-headless.default.svc.cluster.local:9779" | ""    |
+--------------+-----------------------------------------------------------------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+-------+
| 2            | "cbrpnm-storaged-5.cbrpnm-storaged-headless.default.svc.cluster.local:9779" | "cbrpnm-storaged-5.cbrpnm-storaged-headless.default.svc.cluster.local:9779, cbrpnm-storaged-4.cbrpnm-storaged-headless.default.svc.cluster.local:9779, cbrpnm-storaged-3.cbrpnm-storaged-headless.default.svc.cluster.local:9779" | ""    |
+--------------+-----------------------------------------------------------------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+-------+
| 3            | "cbrpnm-storaged-6.cbrpnm-storaged-headless.default.svc.cluster.local:9779" | "cbrpnm-storaged-6.cbrpnm-storaged-headless.default.svc.cluster.local:9779, cbrpnm-storaged-3.cbrpnm-storaged-headless.default.svc.cluster.local:9779, cbrpnm-storaged-5.cbrpnm-storaged-headless.default.svc.cluster.local:9779" | ""    |
+--------------+-----------------------------------------------------------------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+-------+
| 4            | "cbrpnm-storaged-4.cbrpnm-storaged-headless.default.svc.cluster.local:9779" | "cbrpnm-storaged-4.cbrpnm-storaged-headless.default.svc.cluster.local:9779, cbrpnm-storaged-3.cbrpnm-storaged-headless.default.svc.cluster.local:9779, cbrpnm-storaged-6.cbrpnm-storaged-headless.default.svc.cluster.local:9779" | ""    |
+--------------+-----------------------------------------------------------------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+-------+
Got 4 rows (time spent 685/12227 us)

(root@nebula) [s2]> drop zone z1 from group g1
[ERROR (-1005)]: Conflict!

Thu, 14 Oct 2021 11:30:44 CST

[HarrisChu]

@cooper-lzy cc

[HarrisChu]

it can be dropped after drop space, but I think it's not a good idea for user.

(root@nebula) [s2]> drop space s2
Execution succeeded (time spent 734/10356 us)

(root@nebula) [(none)]> drop zone z1 from group g1
Execution succeeded (time spent 808/6687 us)

Thu, 14 Oct 2021 11:39:19 CST

[darionyaphet]

Because create space on G1 and z1 belong to it. Although z1 have no host on it, but should not remove from group

[HarrisChu]

Ok for me, it's much more complex if we verify it dynamically.
Maybe we could enhance it in future.

@critical27 cc.