is_local = 0 in system.clusters when default_database is used #46277
Description
In table system.clusters, column is_local is always 0 when default_database is specified, even if the host resolves to a local address.
This is due to how this function is implemented:
ClickHouse/src/Interpreters/Cluster.cpp
Lines 40 to 53 in 27bc317
I was wondering if this is intended and the reason is still relevant today? "only reason is to avoid query rewrite".
How to reproduce
Create a cluster definition in <remote_servers> in config.xml with default_database. I use this to implement circular replication:
<remote_servers>
<ch_cluster>
<shard>
<internal_replication>true</internal_replication>
<replica>
<host>ch-0.clickhouse</host>
<port>9000</port>
<default_database>stats_0</default_database>
</replica>
<replica>
<host>ch-1.clickhouse</host>
<port>9000</port>
<default_database>stats_1</default_database>
</replica>
</shard>
<shard>
<internal_replication>true</internal_replication>
<replica>
<host>ch-1.clickhouse</host>
<port>9000</port>
<default_database>stats_0</default_database>
</replica>
<replica>
<host>ch-2.clickhouse</host>
<port>9000</port>
<default_database>stats_1</default_database>
</replica>
</shard>
<shard>
<internal_replication>true</internal_replication>
<replica>
<host>ch-2.clickhouse</host>
<port>9000</port>
<default_database>stats_0</default_database>
</replica>
<replica>
<host>ch-0.clickhouse</host>
<port>9000</port>
<default_database>stats_1</default_database>
</replica>
</shard>
</ch_cluster>
</remote_servers>Contents of system.clusters:
select host_address, is_local, default_database from system.clusters where cluster = 'ch_cluster'
┌─host_address─┬─is_local─┬─default_database─┐
│ 10.3.99.160 │ 0 │ stats_0 │
│ 10.3.61.198 │ 0 │ stats_1 │
│ 10.3.61.198 │ 0 │ stats_0 │
│ 10.3.69.69 │ 0 │ stats_1 │
│ 10.3.69.69 │ 0 │ stats_0 │
│ 10.3.99.160 │ 0 │ stats_1 │
└──────────────┴──────────┴──────────────────┘
I would expect that the entries for the host that I'm connected to have is_local = 1:
┌─host_address─┬─is_local─┬─default_database─┐
│ 10.3.99.160 │ 1 │ stats_0 │
│ 10.3.61.198 │ 0 │ stats_1 │
│ 10.3.61.198 │ 0 │ stats_0 │
│ 10.3.69.69 │ 0 │ stats_1 │
│ 10.3.69.69 │ 0 │ stats_0 │
│ 10.3.99.160 │ 1 │ stats_1 │
└──────────────┴──────────┴──────────────────┘