maxConcurrent

How many snapshot and events queries each store runs at once, whichever entry asks; beyond it a query waits, then is wow.query.busy (429, with Retry-After). Not set, each store derives one from the pool it reports: a quarter of a pool its queries share with the appends, at least 2 (MongoDB's, and PostgreSQL's or Elasticsearch's own pool), or the whole of a pool of their own (PostgreSQL's query-data-source, Elasticsearch's query-client); 16 for a store that reports none. That bound then adapts to the store's write pressure (adaptive). 0 for no bound; wow.stores.<name>.query.max-concurrent overrides it for one store.