Add more documentation about the advisory lock ID.

plugin-server/src/worker/ingestion/person-state.ts

@@ -751,8 +751,12 @@ const deferredPersonOverridesProcessedCounter = new Counter({
 })
 
 export class DeferredPersonOverrideWorker {
-    // The advisory lock identifier/key used to ensure that only one process is
-    // updating the overrides at a time.
+    // This lock ID is used as an advisory lock identifier/key for a lock that
+    // that ensures only one worker is able to update the overrides table at a
+    // time. (We do this to make it simpler to ensure we maintain the
+    // consistency of transitive updates.) There isn't any special significance
+    // to this particular value (other than Postgres requires it to be a numeric
+    // one), it just needs to be consistent across all processes.
     public readonly lockId = 567
 
     private writer: PersonOverrideWriter