Add: check for changes to library items

server/utils/queries/libraryFilters.js

@@ -485,6 +485,60 @@ module.exports = {
         }
       }
     } else {
+      // To reduce the cold-start load time, first check if any library items, series,
+      // or authors have had an "updatedAt" timestamp since the last time the filter
+      // data was loaded. If so, we can skip loading all of the data.
+      // Because many items could change, just check the count of items.
+      const lastLoadedAt = cachedFilterData ? cachedFilterData.loadedAt : 0
+
+      const changedBooks = await Database.bookModel.count({
+        include: {
+          model: Database.libraryItemModel,
+          attributes: [],
+          where: {
+            libraryId: libraryId,
+            updatedAt: {
+              [Sequelize.Op.gt]: new Date(lastLoadedAt)
+            }
+          }
+        },
+        where: {
+          updatedAt: {
+            [Sequelize.Op.gt]: new Date(lastLoadedAt)
+          }
+        },
+        limit: 1
+      })
+
+      const changedSeries = await Database.seriesModel.count({
+        where: {
+          libraryId: libraryId,
+          updatedAt: {
+            [Sequelize.Op.gt]: new Date(lastLoadedAt)
+          }
+        },
+        limit: 1
+      })
+
+      const changedAuthors = await Database.authorModel.count({
+        where: {
+          libraryId: libraryId,
+          updatedAt: {
+            [Sequelize.Op.gt]: new Date(lastLoadedAt)
+          }
+        },
+        limit: 1
+      })
+
+      if (changedBooks + changedSeries + changedAuthors === 0) {
+        // If nothing has changed, update the cache to current time for 30 minute
+        // cache time and return the cached data
+        Logger.debug(`Filter data for ${libraryId} has not changed, returning cached data and updating cache time after ${((Date.now() - start) / 1000).toFixed(2)}s`)
+        Database.libraryFilterData[libraryId].loadedAt = Date.now()
+        return cachedFilterData
+      }
+
+      // Something has changed in one of the tables, so reload all of the filter data for library
       const books = await Database.bookModel.findAll({
         include: {
           model: Database.libraryItemModel,