@Override
    public Mono<Void> deleteTags(String collectionName) {
        String namespace = getNamespace(collectionName);
        BsonDocument filter = new BsonDocument("ns", new BsonString(namespace));
        Publisher<DeleteResult> source = context.getConfigDatabase()
                .getCollection("tags")
                .deleteMany(filter);
        return Flux.from(source)
                .then();
    }
apply the shard key to the filter so that mongos know to which MongoDB the command needs to
be sent for better performance
turms-server-common/src/main/java/im/turms/server/common/storage/mongo/operation/TurmsMongoOperations.java