CODEWITHSUNDEEP
azure-cosmosdb
Nok Dev
Nok Dev

Reputation: 5

Cosmos DB order by descending tokenvalue

I have created a helper method to retrieve rows in descending order with continuationtoken using Cosmos DB C# Library. However it returns no rows when I try order by descending. The query works without orderby or orderbydescending. Please let me know what I need to correct to retrieve rows in correct order. 

  public static async Task<(IEnumerable<T> resultRows, string responseContinuation)> GetIAlltemsAsyncOrderByCount(Expression<Func<T,bool>> predicate, Expression<Func<T,object>> orderby,bool descending, int MaxItemCountPerQuery,string continuationToken="")
    {
        var uri = UriFactory.CreateDocumentCollectionUri(DatabaseId, CollectionId);

        var feedOptions = new FeedOptions
        {
            MaxItemCount = MaxItemCountPerQuery
        };

        string responseContinuation = "";

        if (!string.IsNullOrEmpty(continuationToken))
        {
            feedOptions.RequestContinuation = continuationToken;
            responseContinuation = continuationToken;
        }

        var resultRows = new List<T>();

            using (var query = descending ? client.CreateDocumentQuery<T>(uri, feedOptions).Where(predicate).OrderByDescending(orderby).AsDocumentQuery() : client.CreateDocumentQuery<T>(uri, feedOptions).Where(predicate).OrderBy(orderby
                ).AsDocumentQuery())
            {


                if (query.HasMoreResults)
                {
                    var result = await query.ExecuteNextAsync<T>();

                    responseContinuation = result.ResponseContinuation;

                    resultRows.AddRange(result);


                    /* process result */

                }
            }

            return (resultRows, responseContinuation);

    }

Upvotes: 0

Views: 1242

Answers (1)

Bruce Chen
Bruce Chen

Reputation: 18465

According to your description, I checked this issue on my side and found I could encounter the similar issue. Then I used Fiddler to capture the network traces as follows:

enter image description here

As indexing-policies states as follows:

Index kind: Hash (equality queries), Range (equality, range or ORDER BY queries), or Spatial (spatial queries) .

Range supports efficient equality queries, range queries (using >, <, >=, <=, !=), and ORDER BY queries. ORDER By queries by default also require maximum index precision (-1). The data type can be String or Number.

I log into portal to choose my Cosmos DB account and modify the Indexing Policy under Scale & Settings of my collection as follows:

enter image description here

Based on the above changes, I could order by the string data type.

Upvotes: 1

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