The PutAttributes operation creates or replaces attributes in an item. The client may specify new attributes using a combination of the Attribute.X.Name and Attribute.X.Value parameters. The client specifies the first attribute by the parameters Attribute.0.Name and Attribute.0.Value, the second attribute by the parameters Attribute.1.Name and Attribute.1.Value, and so on.

Attributes are uniquely identified in an item by their name/value combination. For example, a single item can have the attributes { "first_name", "first_value" } and { "first_name", second_value" }. However, it cannot have two attribute instances where both the Attribute.X.Name and Attribute.X.Value are the same.

Optionally, the requestor can supply the Replace parameter for each individual attribute. Setting this value to true causes the new attribute value to replace the existing attribute value(s). For example, if an item has the attributes { 'a', '1' }, { 'b', '2'} and { 'b', '3' } and the requestor calls PutAttributes using the attributes { 'b', '4' } with the Replace parameter set to true, the final attributes of the item are changed to { 'a', '1' } and { 'b', '4' }, which replaces the previous values of the 'b' attribute with the new value.

You cannot specify an empty string as an attribute name.

Because Amazon SimpleDB makes multiple copies of client data and uses an eventual consistency update model, an immediate GetAttributes or Select operation (read) immediately after a PutAttributes or DeleteAttributes operation (write) might not return the updated data.

The following limitations are enforced for this operation:

• 256 total attribute name-value pairs per item
• One billion attributes per domain
• 10 GB of total user data storage per domain