diff --git a/keyserver/src/creators/update-creator.js b/keyserver/src/creators/update-creator.js
--- a/keyserver/src/creators/update-creator.js
+++ b/keyserver/src/creators/update-creator.js
@@ -386,31 +386,28 @@
   rawUpdateInfos: $ReadOnlyArray<RawUpdateInfo>,
   viewerInfo: ViewerInfo,
 ): Promise<FetchUpdatesResult> {
-  const { viewer } = viewerInfo;
-
-  const threadIDsNeedingFetch = new Set();
-  const entryIDsNeedingFetch = new Set();
-  let currentUserNeedsFetch = false;
-  const threadIDsNeedingDetailedFetch = new Set(); // entries and messages
-  for (const rawUpdateInfo of rawUpdateInfos) {
-    if (
-      !viewerInfo.threadInfos &&
-      (rawUpdateInfo.type === updateTypes.UPDATE_THREAD ||
-        rawUpdateInfo.type === updateTypes.JOIN_THREAD)
-    ) {
-      threadIDsNeedingFetch.add(rawUpdateInfo.threadID);
-    }
-    if (rawUpdateInfo.type === updateTypes.JOIN_THREAD) {
-      threadIDsNeedingDetailedFetch.add(rawUpdateInfo.threadID);
-    } else if (rawUpdateInfo.type === updateTypes.UPDATE_ENTRY) {
-      entryIDsNeedingFetch.add(rawUpdateInfo.entryID);
-    } else if (rawUpdateInfo.type === updateTypes.UPDATE_CURRENT_USER) {
-      currentUserNeedsFetch = true;
-    }
-  }
+  const entitiesToFetch = rawUpdateInfos
+    .map(info => updateSpecs[info.type].entitiesToFetch?.(info))
+    .filter(Boolean);
+  const currentUserNeedsFetch = entitiesToFetch.some(
+    ({ currentUser }) => currentUser,
+  );
+  const threadIDsNeedingFetch = viewerInfo.threadInfos
+    ? new Set()
+    : new Set(entitiesToFetch.map(({ threadID }) => threadID).filter(Boolean));
+  const entryIDsNeedingFetch = new Set(
+    entitiesToFetch.map(({ entryID }) => entryID).filter(Boolean),
+  );
+  // entries and messages
+  const threadIDsNeedingDetailedFetch = new Set(
+    entitiesToFetch
+      .map(({ detailedThreadID }) => detailedThreadID)
+      .filter(Boolean),
+  );
 
   const promises = {};
 
+  const { viewer } = viewerInfo;
   if (!viewerInfo.threadInfos && threadIDsNeedingFetch.size > 0) {
     promises.threadResult = fetchThreadInfos(viewer, {
       threadIDs: threadIDsNeedingFetch,
diff --git a/lib/shared/updates/join-thread-spec.js b/lib/shared/updates/join-thread-spec.js
--- a/lib/shared/updates/join-thread-spec.js
+++ b/lib/shared/updates/join-thread-spec.js
@@ -102,4 +102,10 @@
     const { threadID } = data;
     return JSON.stringify({ threadID });
   },
+  entitiesToFetch(update: ThreadJoinRawUpdateInfo) {
+    return {
+      threadID: update.threadID,
+      detailedThreadID: update.threadID,
+    };
+  },
 });
diff --git a/lib/shared/updates/update-current-user-spec.js b/lib/shared/updates/update-current-user-spec.js
--- a/lib/shared/updates/update-current-user-spec.js
+++ b/lib/shared/updates/update-current-user-spec.js
@@ -33,4 +33,9 @@
     // user column contains all the info we need to construct the UpdateInfo
     return null;
   },
+  entitiesToFetch() {
+    return {
+      currentUser: true,
+    };
+  },
 });
diff --git a/lib/shared/updates/update-entry-spec.js b/lib/shared/updates/update-entry-spec.js
--- a/lib/shared/updates/update-entry-spec.js
+++ b/lib/shared/updates/update-entry-spec.js
@@ -40,4 +40,9 @@
     const { entryID } = data;
     return JSON.stringify({ entryID });
   },
+  entitiesToFetch(update: EntryRawUpdateInfo) {
+    return {
+      entryID: update.entryID,
+    };
+  },
 });
diff --git a/lib/shared/updates/update-spec.js b/lib/shared/updates/update-spec.js
--- a/lib/shared/updates/update-spec.js
+++ b/lib/shared/updates/update-spec.js
@@ -46,4 +46,10 @@
   ) => void,
   +rawUpdateInfoFromRow: (row: Object) => RawInfo,
   +updateContentForServerDB: (data: Data) => ?string,
+  +entitiesToFetch?: (update: RawInfo) => {
+    +threadID?: string,
+    +detailedThreadID?: string,
+    +entryID?: string,
+    +currentUser?: boolean,
+  },
 };
diff --git a/lib/shared/updates/update-thread-spec.js b/lib/shared/updates/update-thread-spec.js
--- a/lib/shared/updates/update-thread-spec.js
+++ b/lib/shared/updates/update-thread-spec.js
@@ -60,4 +60,9 @@
   updateContentForServerDB(data: ThreadUpdateData) {
     return JSON.stringify({ threadID: data.threadID });
   },
+  entitiesToFetch(update: ThreadRawUpdateInfo) {
+    return {
+      threadID: update.threadID,
+    };
+  },
 });