Reindexing

Sometimes indices get messy. Learn how to reindex your data in CBElasticsearch.

On occasion, due to a mapping or settings change, you will need to reindex data from one index (the "source") to another (the "destination"). You can do this by calling the reindex method on CBElasticsearch's Client component.

getInstance( "Client@cbelasticsearch" )
    .reindex( "oldIndex", "newIndex" );

Asynchronous Reindexing

If you want the work to be done asynchronusly, you can pass false to the waitForCompletion flag. When this flag is set to false the method will return a Task instance, which can be used to follow up on the completion status of the reindex process.

getInstance( "Client@cbelasticsearch" )
    .reindex(
        source = "oldIndex",
        destination = "newIndex",
        waitForCompletion = false
    );

Additional Reindex Options

If you have more settings or constraints for the reindex action, you can pass a struct containing valid options to source and destination.

getInstance( "Client@cbelasticsearch" )
    .reindex(
        source = {
            "index": "oldIndex",
            "type": "testdocs",
            "query": {
                "term": {
                    "active": true
                }
            }
        },
        destination = "newIndex"
    );

Transforming Documents via a Reindex Script

You may also pass a script in to the reindex method to transform objects as they are being transferred from one index to another:

getInstance( "Client@cbelasticsearch" )
    .reindex(
        source = {
            "index": "oldIndex",
            "type": "testdocs",
            "query": {
                "term": {
                    "active": true
                }
            }
        },
        destination = "newIndex",
        script = {
            "lang" : "painless",
            "source" : "if( ctx._source.foo != null && ctx._source.foo == 'baz' ){ ctx._source.foo = 'bar'; }"
        }
    );

Note that a Painless script containing newlines, tabs, or space indentation will throw a parsing error. To work around this limitation, use CBElasticsearch's Util.formatToPainless( string script ) method to remove newlines and indentation:

getInstance( "Client@cbelasticsearch" )
    .reindex(
        // ...
        script = {
            "lang" : "painless",
            "source" : getInstance( "Util@cbelasticsearch" )
                        .formatToPainless( getReindexScript() )
        }
    );

Handling Reindex Errors

If you waitForCompletion and the reindex action fails, a cbElasticsearch.HyperClient.ReindexFailedException will be thrown. You can disable the exception by passing false to the throwOnError parameter:

getInstance( "Client@cbelasticsearch" )
    .reindex(
        source = "oldIndex",
        destination = "newIndex",
        waitForCompletion = false,
        throwOnError = false
    );

As always, check out the Elasticsearch documentation for more specifics on what reindexing is and how it works.