Clickhouse exporter error "retrieved value (type=string) cannot be used as a Conf" when selecting database

[candlerb]

(Raising this as a discussion rather than an issue, as I'm not sure if it's me being dense)

Using otelcol-contrib 0.109.0 under Linux, with the following attempt at config.yaml:

receivers:
  syslog:
    udp:
      listen_address: "[::]:5140"
    protocol: rfc3164
    location: Europe/London

exporters:
  clickhouse:
    endpoint: "tcp://localhost:9000?dial_timeout=10s"
    username: log_ingest
    password: xyzzy
    database: default
    async_insert: true
    ttl: 72h
    compress: lz4
    database: default
    logs_table_name: otel_logs
    traces_table_name: otel_traces
    metrics_table_name: otel_metrics
    create_schema: true
    timeout: 5s

service:
  pipelines:
    logs:
      receivers: [syslog]
      exporters: [clickhouse]

The collector fails to start, with the following error:

otelcol-contrib[7905]: Error: failed to get config: cannot resolve the configuration: retrieved value (type=string) cannot be used as a Conf

That's not very helpful in telling me what the error is, or where the error is!

I had to do a binary chop on the config in order to identify the problematic line. It turns out the fault is here:

    database: default

If I comment out that line, then the collector starts successfully.

Actually, I have three issues now:

1. The error report didn't explain that the problem was with the "database" setting
2. In the documentation, there are several examples showing that the database setting is a string, and indeed the source code confirms this. So I still don't understand what I did wrong.
3. Given the above, how do I point the exporter at a clickhouse database other than "default"? Should I put something in the endpoint or connection_params?

I searched for the string "retrieved value (type=string) cannot be used as a Conf" in both issues and discussions, in both repos "opentelemetry-collector" and "opentelemetry-collector-contrib", and found zero results.

[candlerb]

D'oh, yes it's me being dense after all; I had set database: twice in the same YAML object!

However, I still think the error message could be improved for this case. (As a guess: if there is any YAML decoding error, it treats the whole config as a plain string instead?)