FDDB055: Conflicting index type

Field	Value
Code	FDDB055
Severity	Error

Message

Index '{0}' has conflicting types: {1} on entity '{2}' vs {3} on entity '{4}'

Description

When multiple entities define the same DynamoDB index, they must use the same index type (either all GSI or all LSI). An index cannot be both a Global Secondary Index and a Local Secondary Index.

GSIs and LSIs are fundamentally different DynamoDB constructs. A GSI has its own partition key and optional sort key, while an LSI shares the base table's partition key. The same index name cannot be both.

Example

The following code triggers this diagnostic:

[DynamoDbTable("shared-table", IsDefault = true)]
public partial class Order
{
    [PartitionKey]
    [DynamoDbAttribute("pk")]
    public string Pk { get; set; } = string.Empty;
    [SortKey]
    [DynamoDbAttribute("sk")]
    public string Sk { get; set; } = string.Empty;
    [GsiPartitionKey("date-index")]
    [DynamoDbAttribute("createdAt")]
    public string CreatedAt { get; set; } = string.Empty;
}
[DynamoDbTable("shared-table")]
public partial class Customer
{
    [PartitionKey]
    [DynamoDbAttribute("pk")]
    public string Pk { get; set; } = string.Empty;
    [SortKey]
    [DynamoDbAttribute("sk")]
    public string Sk { get; set; } = string.Empty;
    [LsiSortKey("date-index")]
    [DynamoDbAttribute("createdAt")]
    public string CreatedAt { get; set; } = string.Empty;
}

Fix

The corrected version:

[DynamoDbTable("shared-table", IsDefault = true)]
public partial class Order
{
    [PartitionKey]
    [DynamoDbAttribute("pk")]
    public string Pk { get; set; } = string.Empty;
    [SortKey]
    [DynamoDbAttribute("sk")]
    public string Sk { get; set; } = string.Empty;
    [GsiPartitionKey("date-index")]
    [DynamoDbAttribute("createdAt")]
    public string CreatedAt { get; set; } = string.Empty;
}
[DynamoDbTable("shared-table")]
public partial class Customer
{
    [PartitionKey]
    [DynamoDbAttribute("pk")]
    public string Pk { get; set; } = string.Empty;
    [SortKey]
    [DynamoDbAttribute("sk")]
    public string Sk { get; set; } = string.Empty;
    [GsiPartitionKey("date-index")]
    [DynamoDbAttribute("createdAt")]
    public string CreatedAt { get; set; } = string.Empty;
}