title: DynamoDB write cost
body: <p>In DynamoDB does write cost of <strong>updating</strong> an attribute depends only on <strong>attribute size</strong> or total <strong>item size</strong> also?</p>
  
  <p>Say I have a table with partitionid as <code>userid</code> and each item has around 70 attributes each of value with 200 bytes. Now I update only 1 attribute of this item. Will write cost be 200 bytes, so <strong>1 Write Capacity Unit</strong> or it will depend on item size irrespective of attributes being updated so will be 70*200=1400 so <strong>2 Write Capacity Units</strong>?</p>