How to delete all the documents in DocumentDB through c# code

Question

I'm using a new database from Microsoft called DocumentDB. Now I want to delete a document by ID, but I cannot figure out, how to do this. Delete operation in DocumentDB requires self-links and they are different from my own ids. However I am querying once for document, then I will get the self link. With that self link I am deleting the document.

Now I want to delete all documents around 50000+ documents in my collection.

Need to get each document and then delete or any simple method to do the same?

Can it be possible?

Answer 1

You're correct that deleting documents require a reference to the document's _self link.

If you are looking to delete ALL documents in your collection - it may be simpler and faster to delete and re-create the collection. The only caveat is that server-side scripts (e.g. sprocs, udfs, triggers) also belong to the collection and may need to be re-created as well.

Update: I wrote a quick stored procedure that performs a bulk-delete given a query. This allows you to perform bulk delete operations in fewer network requests.

/**
 * A DocumentDB stored procedure that bulk deletes documents for a given query.<br/>
 * Note: You may need to execute this sproc multiple times (depending whether the sproc is able to delete every document within the execution timeout limit).
 *
 * @function
 * @param {string} query - A query that provides the documents to be deleted (e.g. "SELECT * FROM c WHERE c.founded_year = 2008")
 * @returns {Object.<number, boolean>} Returns an object with the two properties:<br/>
 *   deleted - contains a count of documents deleted<br/>
 *   continuation - a boolean whether you should execute the sproc again (true if there are more documents to delete; false otherwise).
 */
function bulkDeleteSproc(query) {
    var collection = getContext().getCollection();
    var collectionLink = collection.getSelfLink();
    var response = getContext().getResponse();
    var responseBody = {
        deleted: 0,
        continuation: true
    };

    // Validate input.
    if (!query) throw new Error("The query is undefined or null.");

    tryQueryAndDelete();

    // Recursively runs the query w/ support for continuation tokens.
    // Calls tryDelete(documents) as soon as the query returns documents.
    function tryQueryAndDelete(continuation) {
        var requestOptions = {continuation: continuation};

        var isAccepted = collection.queryDocuments(collectionLink, query, requestOptions, function (err, retrievedDocs, responseOptions) {
            if (err) throw err;

            if (retrievedDocs.length > 0) {
                // Begin deleting documents as soon as documents are returned form the query results.
                // tryDelete() resumes querying after deleting; no need to page through continuation tokens.
                //  - this is to prioritize writes over reads given timeout constraints.
                tryDelete(retrievedDocs);
            } else if (responseOptions.continuation) {
                // Else if the query came back empty, but with a continuation token; repeat the query w/ the token.
                tryQueryAndDelete(responseOptions.continuation);
            } else {
                // Else if there are no more documents and no continuation token - we are finished deleting documents.
                responseBody.continuation = false;
                response.setBody(responseBody);
            }
        });

        // If we hit execution bounds - return continuation: true.
        if (!isAccepted) {
            response.setBody(responseBody);
        }
    }

    // Recursively deletes documents passed in as an array argument.
    // Attempts to query for more on empty array.
    function tryDelete(documents) {
        if (documents.length > 0) {
            // Delete the first document in the array.
            var isAccepted = collection.deleteDocument(documents[0]._self, {}, function (err, responseOptions) {
                if (err) throw err;

                responseBody.deleted++;
                documents.shift();
                // Delete the next document in the array.
                tryDelete(documents);
            });

            // If we hit execution bounds - return continuation: true.
            if (!isAccepted) {
                response.setBody(responseBody);
            }
        } else {
            // If the document array is empty, query for more documents.
            tryQueryAndDelete();
        }
    }
}

Answer 2

Here's a solution for deleting documents using the C# SDK. The code below assumes a single database and a single collection. It will iterate all documents in the collection and delete them one at a time. To delete particular databases, collections, or documents, modify the appropriate "CreateQuery" method to include the SQL select syntax. For example, to select a particular database,

db = client.CreateDatabaseQuery().Where(o => o.Id == "MyDocDb").ToList().First();

Sample Code For Deleting All Documents in a DocumentDB Instance with a Single Database and a Single Collection:

using Microsoft.Azure.Documents;
using Microsoft.Azure.Documents.Client;
using Microsoft.Azure.Documents.Linq;
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Util
{
    class Program
    {
        private Uri _docDbUri = new Uri("https://<nameofyourdocdb>.documents.azure.com:443/");
        private string _docDbKey = "<your primary key>";

        private async Task DeleteDocsAsync()
        {
            using (var client = new DocumentClient(_docDbUri, _docDbKey))
            {
                try
                {
                    var db = client.CreateDatabaseQuery().ToList().First();
                    var coll = client.CreateDocumentCollectionQuery(db.CollectionsLink).ToList().First();
                    var docs = client.CreateDocumentQuery(coll.DocumentsLink);
                    foreach (var doc in docs)
                    {
                        await client.DeleteDocumentAsync(doc.SelfLink);
                    }
                }
                catch (Exception ex)
                {
                    Trace.WriteLine(ex);
                    throw;
                }
            }
        }



        static void Main(string[] args)
        {
            try
            {
                Program p = new Program();
                p.DeleteDocsAsync().Wait();
            }
            catch (Exception)
            {
                throw;
            }
        }
    }
}

Answer 3

Here is a way to delete documents with AllowBulkExecution enabled. This method deletes documents in chunks of 100, as currently, cosmos DB supports only a max of 100 operations at once. It takes partition key property name and uses reflection to get its value.

public async Task BulkDeleteDocumentsAsync(IEnumerable<T> entities, string partitionKeyPropertyName)
    {
        List<Task> tasks = new List<Task>(100);
        foreach (var entity in entities)
        {
            var partitionKey = entity.GetType().GetProperty(partitionKeyPropertyName)?.GetValue(entity, null)?.ToString();
            if (partitionKey != null)
            {
                tasks.Add(DeleteDocumentAsync(entity.Id!, partitionKey)
                    .ContinueWith(itemResponse =>
                    {
                        if (!itemResponse.IsCompletedSuccessfully)
                        {
                            AggregateException innerExceptions = itemResponse.Exception!.Flatten();

                            if (innerExceptions.InnerExceptions.FirstOrDefault(innerEx => innerEx is CosmosException) is CosmosException cosmosException)
                            {
                                _logger.LogError($"Cosmos Exception deleting {entity.Id} {cosmosException.StatusCode} ({cosmosException.Message}).");
                            }
                            else
                            {
                                _logger.LogError($"Exception deleting {entity.Id} {innerExceptions.InnerExceptions.FirstOrDefault()}.");
                            }
                        }
                    }));
                if (tasks.Count == 100)
                {
                    await Task.WhenAll(tasks);
                    tasks.Clear();
                }
            }
        }
        await Task.WhenAll(tasks);
    }