diff --git a/server/jest.config.js b/server/jest.config.js
index 1bf199f..4f0f1e2 100644
--- a/server/jest.config.js
+++ b/server/jest.config.js
@@ -19,5 +19,3 @@ module.exports = {
     "<rootDir>/spec/setup_tests.ts"
   ]
 };
-
-process.env.HASTIC_DB_IN_MEMORY = 'true';
diff --git a/server/package.json b/server/package.json
index 44ce637..71f68b4 100644
--- a/server/package.json
+++ b/server/package.json
@@ -30,7 +30,6 @@
     "@types/mongodb": "^3.3.1",
     "@types/nedb": "^1.8.0",
     "@types/zeromq": "^4.6.0",
-    "deasync": "^0.1.15",
     "axios": "^0.18.0",
     "babel-core": "^6.26.3",
     "babel-jest": "^23.4.2",
@@ -38,6 +37,7 @@
     "babel-polyfill": "^6.26.0",
     "babel-preset-env": "^1.7.0",
     "babel-preset-es2015": "^6.24.1",
+    "deasync": "^0.1.15",
     "es6-promise": "^4.2.4",
     "event-stream": "3.3.4",
     "file-loader": "^1.1.11",
diff --git a/server/spec/setup_tests.ts b/server/spec/setup_tests.ts
index e1712b1..a0f9c4c 100644
--- a/server/spec/setup_tests.ts
+++ b/server/spec/setup_tests.ts
@@ -1,6 +1,4 @@
-import * as AnalyticUnit from '../src/models/analytic_units';
-import * as AnalyticUnitCache from '../src/models/analytic_unit_cache_model';
-import { TEST_ANALYTIC_UNIT_ID, createTestDB } from './utils_for_tests/analytic_units';
+import { createTestDB } from './utils_for_tests/analytic_units';
 import { clearSegmentsDB } from './utils_for_tests/segments';
 
 console.log = jest.fn();
@@ -9,8 +7,12 @@ console.error = jest.fn();
 jest.mock('../src/config.ts', () => ({
   DATA_PATH: 'fake-data-path',
   HASTIC_API_KEY: 'fake-key',
-  ZMQ_IPC_PATH: 'fake-zmq-path'
+  ZMQ_IPC_PATH: 'fake-zmq-path',
+  HASTIC_DB_CONNECTION_TYPE: 'nedb',
+  HASTIC_IN_MEMORY_PERSISTANCE: true
 }));
 
+jest.mock('deasync', () => ({ loopWhile: jest.fn() }));
+
 clearSegmentsDB();
 createTestDB();
diff --git a/server/src/config.ts b/server/src/config.ts
index 7539d25..f11a843 100644
--- a/server/src/config.ts
+++ b/server/src/config.ts
@@ -9,11 +9,12 @@ import * as os from 'os';
 let configFile = path.join(__dirname, '../../config.json');
 let configExists = fs.existsSync(configFile);
 
-export type DataBaseConfig = {
+// TODO: move to data_layer
+export type DBConfig = {
   user: string,
   password: string,
   url: string,
-  db_name: string
+  dbName: string
 }
 
 export const ANALYTICS_PATH = path.join(__dirname, '../../analytics');
@@ -130,16 +131,17 @@ function createZMQConnectionString() {
   return zmq;
 }
 
-function getDbConfig(connectionStr: string): DataBaseConfig {
+// TODO: move to data_layer
+function getDbConfig(connectionStr: string): DBConfig {
   const [user, password] = connectionStr.split('@')[0].split(':');
-  const [db_name, ...urlParts] = connectionStr.split('@')[1].split('/').reverse();
+  const [dbName, ...urlParts] = connectionStr.split('@')[1].split('/').reverse();
   const url = urlParts.reverse().join('/');
 
   const config = {
     user,
     password,
     url,
-    db_name
+    dbName
   };
   return config;
 }
diff --git a/server/src/controllers/analytics_controller.ts b/server/src/controllers/analytics_controller.ts
index 58d476b..2eec633 100644
--- a/server/src/controllers/analytics_controller.ts
+++ b/server/src/controllers/analytics_controller.ts
@@ -592,7 +592,7 @@ export async function getDetectionSpans(
 async function getPayloadData(
   analyticUnit: AnalyticUnit.AnalyticUnit,
   from: number,
-  to:number
+  to: number
 ) {
   let range: TimeRange;
   if(from !== undefined && to !== undefined) {
diff --git a/server/src/migrations.ts b/server/src/migrations.ts
index 44315c9..eda9abd 100644
--- a/server/src/migrations.ts
+++ b/server/src/migrations.ts
@@ -17,7 +17,7 @@ const analyticUnitsDB = makeDBQ(Collection.ANALYTIC_UNITS);
 const analyticUnitCachesDB = makeDBQ(Collection.ANALYTIC_UNIT_CACHES);
 const thresholdsDB = makeDBQ(Collection.THRESHOLD);
 
-const DB_META_ID = '0';
+const DB_META_ID = '000000000000000000000001'; //24 symbols for mongodb
 
 type DbMeta = {
   revision: number
diff --git a/server/src/routes/analytic_units_router.ts b/server/src/routes/analytic_units_router.ts
index 60ca392..7d95637 100644
--- a/server/src/routes/analytic_units_router.ts
+++ b/server/src/routes/analytic_units_router.ts
@@ -61,8 +61,9 @@ async function updateUnit(ctx: Router.IRouterContext) {
     throw new Error('Cannot update undefined id');
   }
 
-  const updatedObj = await AnalyticUnit.update(analyticUnitObj.id, analyticUnitObj);
-  const analyticUnit = AnalyticUnit.createAnalyticUnitFromObject(updatedObj);
+  await AnalyticUnit.update(analyticUnitObj.id, analyticUnitObj);
+  // TODO: check if learning is necessary without database query
+  const analyticUnit = await AnalyticUnit.findById(analyticUnitObj.id);
 
   if(analyticUnit.learningAfterUpdateRequired) {
     await AnalyticsController.runLearning(analyticUnitObj.id);
diff --git a/server/src/services/data_layer/basedb.ts b/server/src/services/data_layer/basedb.ts
new file mode 100644
index 0000000..bfac949
--- /dev/null
+++ b/server/src/services/data_layer/basedb.ts
@@ -0,0 +1,15 @@
+import * as nedb from 'nedb';
+import * as mongodb from 'mongodb';
+
+export type dbCollection = nedb | mongodb.Collection;
+
+export interface DbQueryWrapper {
+  dbInsertOne(collection: dbCollection, doc: object): Promise<string>;
+  dbInsertMany(collection: dbCollection, docs: object[]): Promise<string[]>;
+  dbUpdateOne(collection: dbCollection, query: string | object, updateQuery: object): Promise<void>;
+  dbUpdateMany(collection: dbCollection, query: string[] | object, updateQuery: object): Promise<void>;
+  dbFindOne(collection: dbCollection, query: string | object): Promise<any>;
+  dbFindMany(collection: dbCollection, query: string[] | object, sortQuery: object): Promise<any[]>;
+  dbRemoveOne(collection: dbCollection, query: string | object): Promise<boolean>;
+  dbRemoveMany(collection: dbCollection, query: string[] | object): Promise<number>;
+}
diff --git a/server/src/services/data_layer/index.ts b/server/src/services/data_layer/index.ts
new file mode 100644
index 0000000..c7ba43c
--- /dev/null
+++ b/server/src/services/data_layer/index.ts
@@ -0,0 +1,25 @@
+import { DbQueryWrapper, dbCollection } from './basedb';
+import { NeDbQueryWrapper } from './nedb';
+import { MongoDbQueryWrapper } from './mongodb';
+
+import { HASTIC_DB_CONNECTION_TYPE } from '../../config';
+
+export enum DBType {
+  nedb = 'nedb',
+  mongodb = 'mongodb'
+};
+
+export { NeDbQueryWrapper, MongoDbQueryWrapper, DbQueryWrapper, dbCollection };
+
+export function getDbQueryWrapper(): DbQueryWrapper {
+  if(HASTIC_DB_CONNECTION_TYPE === DBType.nedb) {
+    return new NeDbQueryWrapper();
+  }
+  if(HASTIC_DB_CONNECTION_TYPE === DBType.mongodb) {
+    return new MongoDbQueryWrapper();
+  }
+
+  throw new Error(
+    `"${HASTIC_DB_CONNECTION_TYPE}" HASTIC_DB_CONNECTION_TYPE is not supported. Possible values: "nedb", "mongodb"`
+  );
+}
diff --git a/server/src/services/data_layer/mongodb.ts b/server/src/services/data_layer/mongodb.ts
new file mode 100644
index 0000000..223aec6
--- /dev/null
+++ b/server/src/services/data_layer/mongodb.ts
@@ -0,0 +1,117 @@
+import { DbQueryWrapper } from './basedb';
+
+import { Collection, FilterQuery, ObjectID } from 'mongodb';
+import { wrapIdToMongoDbQuery, wrapIdsToMongoDbQuery, isEmptyArray } from './utils';
+
+import * as _ from 'lodash';
+
+
+export class MongoDbQueryWrapper implements DbQueryWrapper {
+
+  async dbInsertOne(collection: Collection, doc: any): Promise<string> {
+    // http://mongodb.github.io/node-mongodb-native/3.1/api/Collection.html#insertOne
+
+    // TODO: move to utils
+    if(doc._id !== undefined) {
+      doc._id = new ObjectID(doc._id);
+    }
+    const newDoc = await collection.insertOne(doc);
+    return newDoc.insertedId.toString();
+  }
+
+  async dbInsertMany(collection: Collection, docs: any[]): Promise<string[]> {
+    // http://mongodb.github.io/node-mongodb-native/3.1/api/Collection.html#insertMany
+    if(docs.length === 0) {
+      return [];
+    }
+
+    // TODO: move to utils
+    docs.forEach(doc => {
+      if(doc._id !== undefined) {
+        doc._id = new ObjectID(doc._id);
+      }
+    });
+    const newDocs = await collection.insertMany(docs);
+    return _.map(newDocs.insertedIds, (id: ObjectID) => id.toString());
+  }
+
+  async dbUpdateOne(collection: Collection, query: FilterQuery<string | object>, updateQuery: any): Promise<void> {
+    // http://mongodb.github.io/node-mongodb-native/3.1/api/Collection.html#updateOne
+
+    // "_id" is immutable. Mongo throws an exception if updateQuery contains "_id" field.
+    if(updateQuery._id !== undefined) {
+      delete updateQuery._id;
+    }
+    let mongodbUpdateQuery = { $set: updateQuery }
+    query = wrapIdToMongoDbQuery(query);
+
+    await collection.updateOne(
+      query,
+      mongodbUpdateQuery
+    );
+  }
+
+  async dbUpdateMany(collection: Collection, query: string[] | object, updateQuery: any): Promise<void> {
+    // http://mongodb.github.io/node-mongodb-native/3.1/api/Collection.html#updateMany
+    if(isEmptyArray(query)) {
+      return;
+    }
+    // "_id" is immutable. Mongo throws an exception if updateQuery contains "_id" field.
+    if(updateQuery._id !== undefined) {
+      delete updateQuery._id;
+    }
+    let mongodbUpdateQuery = { $set: updateQuery };
+    query = wrapIdsToMongoDbQuery(query);
+    await collection.updateMany(
+      query,
+      mongodbUpdateQuery
+    );
+  }
+
+  async dbFindOne(collection: Collection, query: FilterQuery<string | object>): Promise<any> {
+    // http://mongodb.github.io/node-mongodb-native/3.1/api/Collection.html#findOne
+    query = wrapIdToMongoDbQuery(query);
+    let doc = await collection.findOne(query);
+    // TODO: move to utils
+    if(doc !== null) {
+      doc._id = doc._id.toString();
+    }
+    return doc;
+  }
+
+  async dbFindMany(collection: Collection, query: string[] | object, sortQuery: object = {}): Promise<any[]> {
+    // http://mongodb.github.io/node-mongodb-native/3.1/api/Collection.html#find
+    if(isEmptyArray(query)) {
+      return [];
+    }
+    query = wrapIdsToMongoDbQuery(query);
+    const docs = await collection.find(query).sort(sortQuery).toArray();
+    // TODO: move to utils
+    docs.forEach(doc => {
+      if(doc !== null) {
+        doc._id = doc._id.toString();
+      }
+    });
+    return docs;
+  }
+
+  async dbRemoveOne(collection: Collection, query: FilterQuery<string | object>): Promise<boolean> {
+    // http://mongodb.github.io/node-mongodb-native/3.1/api/Collection.html#deleteOne
+    query = wrapIdToMongoDbQuery(query);
+    const deleted = await collection.deleteOne(query);
+    if(deleted.deletedCount > 1) {
+      throw new Error(`Removed ${deleted.deletedCount} elements with query: ${JSON.stringify(query)}. Only one is Ok.`);
+    }
+    return deleted.deletedCount === 1;
+  }
+
+  async dbRemoveMany(collection: Collection, query: string[] | object): Promise<number> {
+    // http://mongodb.github.io/node-mongodb-native/3.1/api/Collection.html#deleteMany
+    if(isEmptyArray(query)) {
+      return 0;
+    }
+    query = wrapIdsToMongoDbQuery(query);
+    const deleted = await collection.deleteMany(query);
+    return deleted.deletedCount;
+  }
+}
diff --git a/server/src/services/data_layer/nedb.ts b/server/src/services/data_layer/nedb.ts
new file mode 100644
index 0000000..cf4cbe6
--- /dev/null
+++ b/server/src/services/data_layer/nedb.ts
@@ -0,0 +1,139 @@
+import { DbQueryWrapper } from './basedb';
+import { wrapIdToQuery, wrapIdsToQuery, isEmptyArray } from './utils';
+
+import * as nedb from 'nedb';
+
+
+export class NeDbQueryWrapper implements DbQueryWrapper {
+  async dbInsertOne(nd: nedb, doc: object): Promise<string> {
+    return new Promise<string>((resolve, reject) => {
+      nd.insert(doc, (err, newDoc: any) => {
+        if(err) {
+          reject(err);
+        } else {
+          resolve(newDoc._id);
+        }
+      })
+    });
+  }
+    
+  async dbInsertMany(nd: nedb, docs: object[]): Promise<string[]> {
+    if(docs.length === 0) {
+      return Promise.resolve([]);
+    }
+    return new Promise<string[]>((resolve, reject) => {
+      nd.insert(docs, (err, newDocs: any[]) => {
+        if(err) {
+          reject(err);
+        } else {
+          resolve(newDocs.map(d => d._id));
+        }
+      });
+    });
+  }
+    
+  async dbUpdateOne(nd: nedb, query: string | object, updateQuery: object): Promise<void> {
+    // https://github.com/louischatriot/nedb#updating-documents
+    let nedbUpdateQuery = { $set: updateQuery }
+    query = wrapIdToQuery(query);
+    return new Promise<any>((resolve, reject) => {
+      nd.update(
+        query,
+        nedbUpdateQuery,
+        { returnUpdatedDocs: true },
+        (err: Error, numAffected: number, affectedDocument: any) => {
+          if(err) {
+            reject(err);
+          } else {
+            resolve();
+          }
+        }
+      );
+    });
+  }
+    
+  async dbUpdateMany(nd: nedb, query: string[] | object, updateQuery: object): Promise<any> {
+    // https://github.com/louischatriot/nedb#updating-documents
+    if(isEmptyArray(query)) {
+      return;
+    }
+    let nedbUpdateQuery = { $set: updateQuery };
+    query = wrapIdsToQuery(query);
+    return new Promise<void>((resolve, reject) => {
+      nd.update(
+        query,
+        nedbUpdateQuery,
+        { returnUpdatedDocs: true, multi: true },
+        (err: Error, numAffected: number, affectedDocuments: any[]) => {
+          if(err) {
+            reject(err);
+          } else {
+            resolve();
+          }
+        }
+      );
+    });
+  }
+  
+  async dbFindOne(nd: nedb, query: string | object): Promise<any> {
+    query = wrapIdToQuery(query);
+    return new Promise<any | null>((resolve, reject) => {
+      nd.findOne(query, (err, doc) => {
+        if(err) {
+          reject(err);
+        } else {
+          resolve(doc);
+        }
+      });
+    });
+  }
+  
+  async dbFindMany(nd: nedb, query: string[] | object, sortQuery: object = {}): Promise<any[]> {
+    if(isEmptyArray(query)) {
+      return Promise.resolve([]);
+    }
+    query = wrapIdsToQuery(query);
+    return new Promise<any[]>((resolve, reject) => {
+      nd.find(query).sort(sortQuery).exec((err, docs: any[]) => {
+        if(err) {
+          reject(err);
+        } else {
+          resolve(docs);
+        }
+      });
+    });
+  }
+  
+  async dbRemoveOne(nd: nedb, query: string | object): Promise<boolean> {
+    query = wrapIdToQuery(query);
+    return new Promise<boolean>((resolve, reject) => {
+      nd.remove(query, { /* options */ }, (err, numRemoved) => {
+        if(err) {
+          reject(err);
+        } else {
+          if(numRemoved > 1) {
+            throw new Error(`Removed ${numRemoved} elements with query: ${JSON.stringify(query)}. Only one is Ok.`);
+          } else {
+            resolve(numRemoved == 1);
+          }
+        }
+      });
+    });
+  }
+  
+  async dbRemoveMany(nd: nedb, query: string[] | object): Promise<number> {
+    if(isEmptyArray(query)) {
+      return Promise.resolve(0);
+    }
+    query = wrapIdsToQuery(query);
+    return new Promise<number>((resolve, reject) => {
+      nd.remove(query, { multi: true }, (err, numRemoved) => {
+        if(err) {
+          reject(err);
+        } else {
+          resolve(numRemoved);
+        }
+      });
+    });
+  }
+}
diff --git a/server/src/services/data_layer/utils.ts b/server/src/services/data_layer/utils.ts
new file mode 100644
index 0000000..5fe55a4
--- /dev/null
+++ b/server/src/services/data_layer/utils.ts
@@ -0,0 +1,41 @@
+import { ObjectID } from 'mongodb';
+
+//TODO: move to DbQueryWrapper
+
+export function wrapIdToQuery(query: string | object): object {
+  if(typeof query === 'string') {
+    return { _id: query };
+  }
+  return query;
+}
+
+export function wrapIdToMongoDbQuery(query: string | object): object {
+  if(typeof query === 'string') {
+    return { _id: new ObjectID(query) };
+  }
+  return query;
+}
+
+export function wrapIdsToQuery(query: string[] | object): object {
+  if(Array.isArray(query)) {
+    return { _id: { $in: query } };
+  }
+  return query;
+}
+
+// mongodb uses ObjectIds to store _id
+// we should wrap ids into ObjectID to generate correct query
+export function wrapIdsToMongoDbQuery(query: string[] | object): object {
+  if(Array.isArray(query)) {
+    query = query.map(id => new ObjectID(id));
+    return { _id: { $in: query } };
+  }
+  return query;
+}
+
+export function isEmptyArray(obj: any): boolean {
+  if(!Array.isArray(obj)) {
+    return false;
+  }
+  return obj.length == 0;
+}
diff --git a/server/src/services/data_service.ts b/server/src/services/data_service.ts
index 2fdb82e..8d71d53 100644
--- a/server/src/services/data_service.ts
+++ b/server/src/services/data_service.ts
@@ -1,3 +1,4 @@
+import { getDbQueryWrapper, dbCollection, DBType } from './data_layer';
 import * as config from '../config';
 
 import * as nedb from 'nedb';
@@ -22,7 +23,7 @@ const COLLECTION_TO_NAME_MAPPING = new Map<Collection, string>([
   [Collection.THRESHOLD, 'threshold'],
   [Collection.DETECTION_SPANS, 'detection_spans'],
   [Collection.DB_META, 'db_meta']
-])
+]);
 
 export enum SortingOrder { ASCENDING = 1, DESCENDING = -1 };
 
@@ -36,13 +37,17 @@ export type DBQ = {
   findMany: (query: string[] | object, sortQuery?: object) => Promise<any[]>,
   insertOne: (document: object) => Promise<string>,
   insertMany: (documents: object[]) => Promise<string[]>,
-  updateOne: (query: string | object, updateQuery: any) => Promise<any>,
-  updateMany: (query: string[] | object, updateQuery: any) => Promise<any[]>,
+  updateOne: (query: string | object, updateQuery: any) => Promise<void>,
+  updateMany: (query: string[] | object, updateQuery: any) => Promise<void>,
   removeOne: (query: string) => Promise<boolean>
   removeMany: (query: string[] | object) => Promise<number>
 }
 
-function dbCollectionFromCollection(collection: Collection): nedb | mongodb.Collection<any> {
+const queryWrapper = getDbQueryWrapper();
+const db = new Map<Collection, dbCollection>();
+let mongoClient: mongodb.MongoClient;
+
+function dbCollectionFromCollection(collection: Collection): dbCollection {
   let dbCollection = db.get(collection);
   if(dbCollection === undefined) {
     throw new Error('Can`t find collection ' + collection);
@@ -52,175 +57,20 @@ function dbCollectionFromCollection(collection: Collection): nedb | mongodb.Coll
 
 export function makeDBQ(collection: Collection): DBQ {
   return {
-    findOne: dbFindOne.bind(null, dbCollectionFromCollection(collection)),
-    findMany: dbFindMany.bind(null, dbCollectionFromCollection(collection)),
-    insertOne: dbInsertOne.bind(null, dbCollectionFromCollection(collection)),
-    insertMany: dbInsertMany.bind(null, dbCollectionFromCollection(collection)),
-    updateOne: dbUpdateOne.bind(null, dbCollectionFromCollection(collection)),
-    updateMany: dbUpdateMany.bind(null, dbCollectionFromCollection(collection)),
-    removeOne: dbRemoveOne.bind(null, dbCollectionFromCollection(collection)),
-    removeMany: dbRemoveMany.bind(null, dbCollectionFromCollection(collection))
+    findOne: queryWrapper.dbFindOne.bind(null, dbCollectionFromCollection(collection)),
+    findMany: queryWrapper.dbFindMany.bind(null, dbCollectionFromCollection(collection)),
+    insertOne: queryWrapper.dbInsertOne.bind(null, dbCollectionFromCollection(collection)),
+    insertMany: queryWrapper.dbInsertMany.bind(null, dbCollectionFromCollection(collection)),
+    updateOne: queryWrapper.dbUpdateOne.bind(null, dbCollectionFromCollection(collection)),
+    updateMany: queryWrapper.dbUpdateMany.bind(null, dbCollectionFromCollection(collection)),
+    removeOne: queryWrapper.dbRemoveOne.bind(null, dbCollectionFromCollection(collection)),
+    removeMany: queryWrapper.dbRemoveMany.bind(null, dbCollectionFromCollection(collection))
   }
 }
 
-function wrapIdToQuery(query: string | object): any {
-  if(typeof query === 'string') {
-    return { _id: query };
-  }
-  return query;
-}
 
-function wrapIdsToQuery(query: string[] | object): any {
-  if(Array.isArray(query)) {
-    return { _id: { $in: query } };
-  }
-  return query;
-}
-
-// TODO: move to utils
-function isEmptyArray(obj: any): boolean {
-  if(!Array.isArray(obj)) {
-    return false;
-  }
-  return obj.length == 0;
-}
-
-const db = new Map<Collection, nedb | mongodb.Collection<any>>();
-let mongoClient: mongodb.MongoClient;
 
 
-async function dbInsertOne(nd: nedb, doc: object): Promise<string> {
-  return new Promise<string>((resolve, reject) => {
-    nd.insert(doc, (err, newDoc: any) => {
-      if(err) {
-        reject(err);
-      } else {
-        resolve(newDoc._id);
-      }
-    })
-  });
-}
-
-async function dbInsertMany(nd: nedb, docs: object[]): Promise<string[]> {
-  if(docs.length === 0) {
-    return Promise.resolve([]);
-  }
-  return new Promise<string[]>((resolve, reject) => {
-    nd.insert(docs, (err, newDocs: any[]) => {
-      if(err) {
-        reject(err);
-      } else {
-        resolve(newDocs.map(d => d._id));
-      }
-    });
-  });
-}
-
-async function dbUpdateOne(nd: nedb, query: string | object, updateQuery: object): Promise<any> {
-  // https://github.com/louischatriot/nedb#updating-documents
-  let nedbUpdateQuery = { $set: updateQuery }
-  query = wrapIdToQuery(query);
-  return new Promise<any>((resolve, reject) => {
-    nd.update(
-      query,
-      nedbUpdateQuery,
-      { returnUpdatedDocs: true },
-      (err: Error, numAffected: number, affectedDocument: any) => {
-        if(err) {
-          reject(err);
-        } else {
-          resolve(affectedDocument);
-        }
-      }
-    );
-  });
-}
-
-async function dbUpdateMany(nd: nedb, query: string[] | object, updateQuery: object): Promise<any[]> {
-  // https://github.com/louischatriot/nedb#updating-documents
-  if(isEmptyArray(query)) {
-    return Promise.resolve([]);
-  }
-  let nedbUpdateQuery = { $set: updateQuery };
-  query = wrapIdsToQuery(query);
-  return new Promise<any[]>((resolve, reject) => {
-    nd.update(
-      query,
-      nedbUpdateQuery,
-      { returnUpdatedDocs: true, multi: true },
-      (err: Error, numAffected: number, affectedDocuments: any[]) => {
-        if(err) {
-          reject(err);
-        } else {
-          resolve(affectedDocuments);
-        }
-      }
-    );
-  });
-}
-
-async function dbFindOne(nd: nedb, query: string | object): Promise<any> {
-  query = wrapIdToQuery(query);
-  return new Promise<any | null>((resolve, reject) => {
-    nd.findOne(query, (err, doc) => {
-      if(err) {
-        reject(err);
-      } else {
-        resolve(doc);
-      }
-    });
-  });
-}
-
-async function dbFindMany(nd: nedb, query: string[] | object, sortQuery: object = {}): Promise<any[]> {
-  if(isEmptyArray(query)) {
-    return Promise.resolve([]);
-  }
-  query = wrapIdsToQuery(query);
-  return new Promise<any[]>((resolve, reject) => {
-    nd.find(query).sort(sortQuery).exec((err, docs: any[]) => {
-      if(err) {
-        reject(err);
-      } else {
-        resolve(docs);
-      }
-    });
-  });
-}
-
-async function dbRemoveOne(nd: nedb, query: string | object): Promise<boolean> {
-  query = wrapIdToQuery(query);
-  return new Promise<boolean>((resolve, reject) => {
-    nd.remove(query, { /* options */ }, (err, numRemoved) => {
-      if(err) {
-        reject(err);
-      } else {
-        if(numRemoved > 1) {
-          throw new Error(`Removed ${numRemoved} elements with query: ${JSON.stringify(query)}. Only one is Ok.`);
-        } else {
-          resolve(numRemoved == 1);
-        }
-      }
-    });
-  });
-}
-
-async function dbRemoveMany(nd: nedb, query: string[] | object): Promise<number> {
-  if(isEmptyArray(query)) {
-    return Promise.resolve(0);
-  }
-  query = wrapIdsToQuery(query);
-  return new Promise<number>((resolve, reject) => {
-    nd.remove(query, { multi: true }, (err, numRemoved) => {
-      if(err) {
-        reject(err);
-      } else {
-        resolve(numRemoved);
-      }
-    });
-  });
-}
-
 function maybeCreateDir(path: string): void {
   if(fs.existsSync(path)) {
     return;
@@ -237,10 +87,10 @@ function checkDataFolders(): void {
 }
 
 async function connectToDb() {
-  if(config.HASTIC_DB_CONNECTION_TYPE === 'nedb') {
+  if(config.HASTIC_DB_CONNECTION_TYPE === DBType.nedb) {
     checkDataFolders();
     const inMemoryOnly = config.HASTIC_DB_IN_MEMORY;
-    console.log('NeDB used as storage');
+    console.log('NeDB is used as the storage');
     // TODO: it's better if models request db which we create if it`s needed
     db.set(Collection.ANALYTIC_UNITS, new nedb({ filename: config.ANALYTIC_UNITS_DATABASE_PATH, autoload: true, timestampData: true, inMemoryOnly}));
     db.set(Collection.ANALYTIC_UNIT_CACHES, new nedb({ filename: config.ANALYTIC_UNIT_CACHES_DATABASE_PATH, autoload: true, inMemoryOnly}));
@@ -248,8 +98,8 @@ async function connectToDb() {
     db.set(Collection.THRESHOLD, new nedb({ filename: config.THRESHOLD_DATABASE_PATH, autoload: true, inMemoryOnly}));
     db.set(Collection.DETECTION_SPANS, new nedb({ filename: config.DETECTION_SPANS_DATABASE_PATH, autoload: true, inMemoryOnly}));
     db.set(Collection.DB_META, new nedb({ filename: config.DB_META_PATH, autoload: true, inMemoryOnly}));
-  } else {
-    console.log('MongoDB used as storage');
+  } else if(config.HASTIC_DB_CONNECTION_TYPE === DBType.mongodb) {
+    console.log('MongoDB is used as the storage');
     const dbConfig = config.HASTIC_DB_CONFIG;
     const uri = `mongodb://${dbConfig.user}:${dbConfig.password}@${dbConfig.url}`;
     const auth = {
@@ -262,11 +112,11 @@ async function connectToDb() {
       autoReconnect: true,
       useUnifiedTopology: true,
       authMechanism: 'SCRAM-SHA-1',
-      authSource: dbConfig.db_name
+      authSource: dbConfig.dbName
     });
     try {
       const client: mongodb.MongoClient = await mongoClient.connect();
-      const hasticDb: mongodb.Db = client.db(dbConfig.db_name);
+      const hasticDb: mongodb.Db = client.db(dbConfig.dbName);
       COLLECTION_TO_NAME_MAPPING.forEach((name, collection) => {
         db.set(collection, hasticDb.collection(name));
       });
@@ -274,6 +124,10 @@ async function connectToDb() {
       console.log(`got error while connect to MongoDB ${err}`);
       throw err;
     }
+  } else {
+    throw new Error(
+      `"${config.HASTIC_DB_CONNECTION_TYPE}" HASTIC_DB_CONNECTION_TYPE is not supported. Possible values: "nedb", "mongodb"`
+    );
   }
 }