Purge old objects in sync cache after upload

chrome/content/zotero/xpcom/sync/syncEngine.js

@@ -204,7 +204,7 @@ Zotero.Sync.Data.Engine.prototype.stop = function () {
 
 
 /**
- * Download updated objects from API and save to local cache
+ * Download updated objects from API and save to DB
  *
  * @return {Promise<Integer>} - A download result code (this.DOWNLOAD_RESULT_*)
  */
@@ -1107,6 +1107,11 @@ Zotero.Sync.Data.Engine.prototype._uploadObjects = Zotero.Promise.coroutine(func
 				objectsClass.updateSynced(updateSyncedIDs, true);
 			}.bind(this));
 			
+			// Purge older objects in sync cache
+			if (toSave.length) {
+				yield Zotero.Sync.Data.Local.purgeCache(objectType, this.libraryID);
+			}
+			
 			// Handle failed objects
 			for (let index in results.failed) {
 				let { code, message, data } = results.failed[index];

chrome/content/zotero/xpcom/sync/syncLocal.js

@@ -1104,6 +1104,21 @@ Zotero.Sync.Data.Local = {
 	},
 	
 	
+	/**
+	 * Delete entries from sync cache that don't exist or are less than the current object version
+	 */
+	purgeCache: Zotero.Promise.coroutine(function* (objectType, libraryID) {
+		var syncObjectTypeID = Zotero.Sync.Data.Utilities.getSyncObjectTypeID(objectType);
+		var table = Zotero.DataObjectUtilities.getObjectsClassForObjectType(objectType).table;
+		var sql = "DELETE FROM syncCache WHERE ROWID IN ("
+			+ "SELECT SC.ROWID FROM syncCache SC "
+			+ `LEFT JOIN ${table} O USING (libraryID, key, version) `
+			+ "WHERE syncObjectTypeID=? AND SC.libraryID=? AND "
+			+ "(O.libraryID IS NULL OR SC.version < O.version)";
+		yield Zotero.DB.queryAsync(sql, [syncObjectTypeID, libraryID]);
+	}),
+	
+	
 	processConflicts: Zotero.Promise.coroutine(function* (objectType, libraryID, conflicts, options = {}) {
 		if (!conflicts.length) return [];
 		

test/tests/syncEngineTest.js

@@ -682,6 +682,10 @@ describe("Zotero.Sync.Data.Engine", function () {
 					assert.isArray(cached.data.conditions);
 					break;
 				}
+				
+				// Make sure older versions have been removed from the cache
+				let versions = yield Zotero.Sync.Data.Local.getCacheObjectVersions(type, libraryID, key);
+				assert.sameMembers(versions, [version]);
 			}
 		})