A data feed is an XML or spreadsheet file made up of a list of products which use groupings of attributes that define each one of your products in a unique way. Attributes, such as 'condition' and 'availability', can have standardized values, or accepted "answers," or attributes can be open to fill with your own choice of value, such as 'id' or 'title'. Accurately describing your items using these attributes allows users to search and find your items more easily.
This data file is being uploaded by the merchant in Google's Mechant portal using FTP or manual upload process.After you've submitted your products to your data feed, a status will be assigned to your products that will determine whether they are eligible to appear on Google Shopping. Also the merchant is able to view / track their published product performance and status in the merchant dashboard. If you're using Adwords campaign, you can directly see what products has the higher number of page views or the most visited items in a period of time.
For more info about Data Feeds read here: https://support.google.com/merchants/?hl=en#topic=3404778
Backing up your data feeds
Now, I wanna share a very simple tutorial on how to backup your existing data feeds before doing any updates.Why it is important? Data Feeds usually being updated by just uploading a new bulk list however,in some cases you'll find it easy to change or override only the specific item's attribute like the price.And if you don't have the original data feed file in Google Spreadsheet format in you hand so, your option is to download the existing feed, edit it and upload back to update.
Here are the steps:
1. Login to Google Merchant dashboard (I assumed you already had an account, you can use your gmail account anyway) : http://www.google.com/merchants/merchantdashboard
2. Click the Data Feeds menu then, find the Status column, click the Items Inserted link and you will be directed to Feed Status summary page.
3. In the feed status summary > feed details, look for the DOWNLOAD FEED link then, click
4. Wait the feed to finish downloading ( you can pres CTRL + J to check the download status)
5. Open the data feed file using a notepad and start searching an item using its ID value
Note: Its not easy to read text on Tab Delimited / text format.Be patient.
6. When done upload it back in the Google Merchant.
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