Function coalesced_audience_column 

pub fn coalesced_audience_column(qualifier: &str, param: usize) -> String

COALESCE(<qualifier>.audience, $<param>) – a row’s own stamp, or the deployment’s MICROMEGAS_DEFAULT_AUDIENCE for a row written before this stage (a NULL column). qualifier is inlined as SQL text, so it must be a trusted table name or alias, never user input; the default stays a bind parameter, since it is operator-supplied config.

This is the shared shape of every site that reads an audience out of Postgres off a physical column – the blocks view’s data_sql, metadata::find_process, and audience_guard’s owner_query_sql. param is the 1-based placeholder index the caller will bind the default to.