Is DynamoDB's C# API DescribeTableResponse returning incorrect data?

Question

I have a simple DynamoDB table with a Hash Key and an Index

Table:

• Name: bank-statements

• Hash Key: MTSTransactionID of type N

• Index: StatementType-index of type S

When I do this:

DescribeTableResponse descResponse = _dynamoDbClient.DescribeTable(new DescribeTableRequest
                {TableName = "bank-statements"});

tableDescription = descResponse.Table;

then,

• tableDescription.AttributeDefinitions.Count = 2. The 2 items are the Key and the Index
• tableDescription.KeySchema.Count = 1. The 1 item is the Key

Then I use the tableDescription to recreate the table by doing this:

CreateTableRequest createTableRequest = new CreateTableRequest
{
   TableName = tableDescription.TableName,
   AttributeDefinitions = tableDescription.AttributeDefinitions,
   KeySchema = tableDescription.KeySchema,
   ProvisionedThroughput = new ProvisionedThroughput
   {
      ReadCapacityUnits = tableDescription.ProvisionedThroughput.ReadCapacityUnits,
      WriteCapacityUnits = tableDescription.ProvisionedThroughput.WriteCapacityUnits
   }
 };

 CreateTableResponse response = _dynamoDbClient.CreateTable(createTableRequest);

However, this produces an error:

One or more parameter values were invalid: Number of attributes in KeySchema does not exactly match number of attributes defined in AttributeDefinitions

Which is true but means either

• the data being returned is wrong
• The error is incorrect as clearly the table does not need that constraint

What can I do to use the DescribeTableResponse to recreate the table anew?

Answer 1

The issue is that you have a key that is used by your index but you aren't creating the index. That leaves you with an unused key.