Writing same data in IndexedDB first time and second time takes much difference in total storing time. why?

I stored some jpeg files (exactly 350, same files same size. Total: 336.14 MB) as Blob in IndexedDB. It took around 1 second to complete the transaction. Then I read all the data to an array and again sored to IndexedDB. But this time it takes around 15 Seconds. I observed this as a consistent behavior. Anything wrong here? I used performance.now() to get the time difference

Files: 350, Size of each: 937 KB, Browser: Chrome and Chromium Edge

    //Open  var dbOpen = indexedDB.open(INDEXED_DB_NAME, INDEXED_DB_VERSION);  dbOpen.onupgradeneeded = function (e) {      console.log("onupgradeneeded");      var store = e.currentTarget.result.createObjectStore(          IMAGE_DATA_STORE, { autoIncrement: true });  };  dbOpen.onsuccess = function (e) {      image_data_db = dbOpen.result;      console.log("indexed DB opened");  };  //Initial Write      var inputFiles = document.getElementById('inputFiles');            for (var i = 0; i < inputFiles.files.length; i++) {          let file = inputFiles.files[i];          var b = new Blob([file], { type: file.type });          fileblobs.push(b);      }      StoreIdb(fileblobs); // < First write        //StoreIdb()          var trx = image_data_db.transaction(IMAGE_DATA_STORE, 'readwrite');      var imagestore = trx.objectStore(IMAGE_DATA_STORE);      for (i = 0; i < fileblobs.length; i++) {          request = imagestore.add(fileblobs[i]);          request.onsuccess = function (e) {              console.log('added');          };          request.onerror = function (e) {              console.error("Request Error", this.error);          };      }      trx.onabort = function (e) {          console.error("Exception:", this.error, this.error.name);      };      trx.oncomplete = function (e) {          console.log('completed');      }            //Read      var objectStore = image_data_db.transaction(IMAGE_DATA_STORE).objectStore(IMAGE_DATA_STORE);      objectStore.openCursor().onsuccess = function (e) {          var cursor = e.target.result;          if (cursor) {             blobArray.push(cursor.value.blob);              cursor.continue();          }          else          {              // completed           }      }    // blobArray will be used for second time << Second Write  

https://stackoverflow.com/questions/66864271/writing-same-data-in-indexeddb-first-time-and-second-time-takes-much-difference March 30, 2021 at 11:06AM