An Error Is Reported in Logs When the Auxiliary ZooKeeper or Replica Data Is Used to Synchronize Table Data

Question

An error is reported in logs when the auxiliary ZooKeeper or replica data is used to synchronize table data.

DB::Exception: Cannot parse input: expected 'quorum:' before: 'merge_type: 2'...
Too many parts (315). Merges are processing significantly slower than inserts...

Answer

The versions of replication table replicas are inconsistent, causing compatibility issues. The table schema contains TTL statements. TTL_DELETE is added in versions later than ClickHouse 20.9, which cannot be identified in earlier versions. This issue occurs when the replication table replica of a later version is elected as the leader.

You can modify the config.xml file of ClickHouse of a later version to avoid such an issue. Ensure that the replication table replicas are the same as those of ClickHouse.