title: DynamoDB - limit on number of tables per account
body: <p>We are working on deploying our product (currently on prem) on AWS and are looking at DynamoDB as a alternative to Cassandra mainly to avoid the devop costs associated with a large number of Cassandra clusters.</p>
  
  <p>The DynamoDB doc says that the per account limit on the number of tables is 256 per region but can be increased by calling AWS support. How much is the max limit for this per account?</p>
  
  <p>Our product is separated into distinct logical units where each such unit will have several tables (say 100). Each customer can have several of such units. Each logical unit can be backed up (i.e. a snapshot taken) and that snapshot can be restored at any time in the future (to overwrite the current content of all tables). The backup/restore performance  - time taken to take a snapshot/import old data for all the tables - need to be good - it cannot be several minutes/hrs.</p>
  
  <p>We were thinking of using distinct set of tables for each such logical unit - so that backup/restore is quick using EMR on S3. But if we follow this approach, we will run out of the 256 table number limit even with one customer. Looks like there are 2 options</p>
  
  <ol>
  <li><p>Create a new account for each such logical unit for each customer. Is this possible? We will have a main corporate account I suppose (I am still learning about this), but can it have a set of sub-accounts for our customers using IAM each of which is considered as an independent AWS account?</p></li>
  <li><p>Use each table in a true multi-tenant manner - where the primary key contains the customer id + logical unit id. But in this scenario,when using EMR to backup an entire table, we will need to selectively back up specific set of rows/items which may be in millions and this will go on while other write/read operations are going on on a different set of items. Is this feasible in terms of large scale?</p></li>
  <li><p>Any other thoughts on how to approach this?</p></li>
  </ol>
  
  <p>Thanks for any info.</p>