NEST - Atomically change an alias to point to another index

Question

Elasticsearch supports renaming an alias atomically, see here:

Renaming an alias is a simple remove then add operation within the same API. This operation is atomic, no need to worry about a short period of time where the alias does not point to an index.

curl -XPOST 'http://localhost:9200/_aliases' -d '
{
    "actions" : [
        { "remove" : { "index" : "test1", "alias" : "alias1" } },
        { "add" : { "index" : "test1", "alias" : "alias2" } }
    ]
}'

With NEST, the same can be achieved via Client.Rename.

Turns out, it's also possible to atomically update an alias to point to a different index:

curl -XPOST 'http://localhost:9200/_aliases' -d '
{
    "actions" : [
        { "remove" : { "index" : "test1", "alias" : "alias1" } },
        { "add" : { "index" : "test2", "alias" : "alias1" } }
    ]
}'

Any way to do the latter directly in NEST?

Right now, I'm using Client.RemoveAlias followed by Client.Alias which is not atomic.

UPDATE: turns out, it's possible to do this by POSTing raw JSON via client.Raw.IndicesUpdateAliasesPost, but I still wonder if there's an easier way. If not, I'm planning to add this to NEST myself.

Answer 1

The NEST client currently supports this functionality. Please use the Client.Swap method.

Answer 2

private void SwapAliases(IElasticClient client, string sourceIndexName, string destinationIndexName)
{
    var aliasNames = client.GetAliasesPointingToIndex(sourceIndexName).Select(a => a.Name);
    var bulkAliasDescriptor = new BulkAliasDescriptor();

    foreach (var aliasName in aliasNames)
    {
        // Remove the alias from the source index
        bulkAliasDescriptor.Remove(a => a.Index(sourceIndexName).Alias(aliasName));

        // Add the alias to the destination index
        bulkAliasDescriptor.Add(a => a.Index(destinationIndexName).Alias(aliasName));
    }

    // Execute the alias swap
    var response = client.Alias(bulkAliasDescriptor);
}