Document minTargetHits resolution formula and grouped topology interaction

en/reference/querying/yql.html

@@ -2277,6 +2277,19 @@ <h2 id="annotations">Annotations</h2>
       and this parameter protects against that when totalTargetHits leads to some node with
       little content otherwise getting a low targetHits.
       </p>
+      <p>
+      Each content node resolves its per-node target hits as
+      <code>max(minTargetHits, ceil(totalTargetHits &times; share))</code>, where <code>share</code>
+      is the node's share of the active documents in the
+      <a href="../applications/services/content.html#group">group</a> serving the query - not across
+      the whole cluster, since a query is dispatched to a single group. A node that has just joined
+      the cluster, or is still receiving documents after a topology change, temporarily holds little
+      content and would get too few hits from <code>totalTargetHits</code> alone without this floor.
+      </p>
+      {% include note.html content="Setting minTargetHits higher than a node's expected share of
+      totalTargetHits makes minTargetHits the effective value, and totalTargetHits has no further
+      effect until it exceeds the floor. This is easy to hit when moving from a flat to a grouped
+      topology, since a group typically has fewer nodes than the full cluster."%}
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