poorbarcode opened a new pull request, #25312:
URL: https://github.com/apache/pulsar/pull/25312
### Motivation
The situation that replication does not work as expected.
- cluster: `c1`
- namespace: `public/default`
The system topic `__change_events` has already been created as a
non-partitioned topic; in other words, the topic named `__change_events` has no
partition.
- cluster: `c2`, has the following configurations
- `allowAutoTopicCreationType=partitioned`
- `defaultNumPartitions=1`
These two configurations mean that the new topic will be created as a
partitioned topic and contain `1` partition.
If we enable replication for the namespace between two clusters, the
following issue will happen
- The cluster `c2` will create a partitioned topic `__change_events` , and
it will have a partition like this `__change_events-partition-0`
- The cluster `c1` will start replication for the non-partitioned topic
`__change_events`, which triggers a non-partitioned topic creation on the `c2`
cluster.
- `c2` will also start a replication to `c1` since it has a partitioned
topic which has a partition named `__change_events-partition-0`, it triggers a
partitioned creation on `c1` cluster.
Eventually, both clusters will hold both partitioned topics and
non-partitioned topics as follows, but they have the same name.
- `admin/partitioned-toipic`: `{partitions: 1}`
- `managed-ledger/persistent`: `[__change_events-partition-0,
__change_events]`
Because this is a system topic, it will lead to fragmentation and cause
serious problems
### Modifications
- Create a topic with the same type as the remote side, if the topic has
already been created on the remote side.
- The change only affects if the following conditions match
- Enable replication
- The topic creation was triggered by `consumer/producer`'s starting
- The remote side has already created the topic
- `broker.conf -> isCreateTopicToRemoteClusterForReplication` is `true`
- enabled topic auto-creation
### Documentation
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- [ ] `doc` <!-- Your PR contains doc changes. -->
- [ ] `doc-required` <!-- Your PR changes impact docs and you will update
later -->
- [x] `doc-not-needed` <!-- Your PR changes do not impact docs -->
- [ ] `doc-complete` <!-- Docs have been already added -->
### Matching PR in forked repository
PR in forked repository: x
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