I have a custom examine indexer using the ISimpleDataService similar to this article: https://24days.in/umbraco-cms/2016/custom-data-and-examine-searching/

public class ReviewIndexer : ISimpleDataService
{
      public IEnumerable<SimpleDataSet> GetAllData(string indexType)
        {
            // Ensure that an Umbraco context is available
            if (UmbracoContext.Current == null)
            {
                var dummyContext = new HttpContextWrapper(new HttpContext(new SimpleWorkerRequest("/", string.Empty, new StringWriter())));
                UmbracoContext.EnsureContext(
                    dummyContext,
                    ApplicationContext.Current,
                    new WebSecurity(dummyContext, ApplicationContext.Current),
                    UmbracoConfig.For.UmbracoSettings(),
                    UrlProviderResolver.Current.Providers,
                    false);
            }

            var dataSets = new List<SimpleDataSet>();

            try
            {
                var service = new ReviewService("mysite");
                var reviews = service.LoadAllReviewsFromDisk();

                // Looping all the raw models and adding them to the dataset
                foreach (var r in reviews)
                {
                    var simpleDataSet = new SimpleDataSet
                    {
                        NodeDefinition = new IndexedNode(),
                        RowData = new Dictionary<string, string>()
                    };

                    simpleDataSet = ReviewToIndexItem(r, simpleDataSet, indexType);

                    dataSets.Add(simpleDataSet);
                }
            }
            catch (Exception ex)
            {
                LogHelper.Error<ReviewIndexer>("error indexing:", ex);
            }

            return dataSets;
        }

        private SimpleDataSet ReviewToIndexItem(ReviewModel r, SimpleDataSet simpleDataSet, string indexType)
        {
            simpleDataSet.NodeDefinition.NodeId = r.Id;
            simpleDataSet.NodeDefinition.Type = indexType;
            simpleDataSet.RowData.Add("id", r.Id.ToString());
            simpleDataSet.RowData.Add("name", r.Name);
            simpleDataSet.RowData.Add("date", r.Date.ToString());
            simpleDataSet.RowData.Add("destination", r.Destination);
            simpleDataSet.RowData.Add("hotel", r.Hotel);
            simpleDataSet.RowData.Add("hotelRating", r.HotelRating.ToString());
            simpleDataSet.RowData.Add("rating", r.Rating.ToString());
            simpleDataSet.RowData.Add("showComment", r.ShowComment.ToString());
            simpleDataSet.RowData.Add("text", r.Text);
            simpleDataSet.RowData.Add("photo", r.Photo);

            return simpleDataSet;
        }
    }
}

However "mysite" is hardcoded and with this multi-site solutions I would like to get this based on indexer name ExamineSetting.config or maybe IndexParentId or SetName on IndexSet in ExamineIndex.config. E.g. instead of "mysite" it could be the root ids or root names of each site.

When having data as Umbraco content nodes, you can configurate Examine with IndexParentId, so it only use data with the specified parent id.

ExamingIndex.config:

<IndexSet SetName="MysiteExternalReviewIndexSet" IndexPath="~/App_Data/TEMP/ExamineIndexes/{machinename}/MysiteExternalReviewIndexSet/" IndexParentId="1234">
      <IndexUserFields>
        <add Name="id"/>
        <add Name="city"/>
        <add Name="name"/>
        <add Name="date" />
        <add Name="destination" />
        <add Name="hotel"/>
        <add Name="hotelRating"/>
        <add Name="rating"/>
        <add Name="showComment" />   
        <add Name="text"/>
        <add Name="photo"/>
      </IndexUserFields>
</IndexSet>

ExamingSettings.config:

<add name="MysiteExternalReviewIndexer" type="Examine.LuceneEngine.Providers.SimpleDataIndexer, Examine"
               dataService="MyProject.Library.Indexing.ReviewIndexer, MyProject.Library"
               indexTypes="Review"
               indexSet="MysiteExternalReviewIndexSet"
               runAsync="false" />

Can I somehow access the current indexer or indexset inside GetAllData method?

/Bjarne