diff --git a/lib/db.js b/lib/db.js
index 06443074..90e98b06 100644
--- a/lib/db.js
+++ b/lib/db.js
@@ -13,7 +13,10 @@ export function getDatabase(database, databaseType, fallback) {
   }
 
   if (!type) {
-    return getDatabase(fallback);
+    if (fallback) {
+      return getDatabase(fallback);
+    }
+    return null;
   }
 
   return type;
diff --git a/lib/kafka.js b/lib/kafka.js
index 987b9d25..39320728 100644
--- a/lib/kafka.js
+++ b/lib/kafka.js
@@ -34,11 +34,15 @@ const kafka = global.kafka || getClient();
 let kafkaProducer = null;
 
 (async () => {
-  kafkaProducer = global.kakfaProducer || (await getProducer());
+  if (kafka) {
+    kafkaProducer = global.kakfaProducer || (await getProducer());
+  }
 
   if (process.env.NODE_ENV !== 'production') {
     global.kafka = kafka;
-    global.kakfaProducer = kafkaProducer;
+    if (kafka) {
+      global.kakfaProducer = kafkaProducer;
+    }
   }
 })();
 
diff --git a/lib/relational.js b/lib/relational.js
index 28de7531..e5b9f2ce 100644
--- a/lib/relational.js
+++ b/lib/relational.js
@@ -7,7 +7,7 @@ import {
   POSTGRESQL,
   POSTGRESQL_DATE_FORMATS,
 } from 'lib/constants';
-import { getDatabase } from './db';
+import { getDatabase } from 'lib/db';
 import moment from 'moment-timezone';
 
 const options = {
@@ -32,6 +32,7 @@ function getClient(options) {
 
   return prisma;
 }
+
 const prisma = global.prisma || getClient(options);
 
 if (process.env.NODE_ENV !== 'production') {
@@ -41,7 +42,7 @@ if (process.env.NODE_ENV !== 'production') {
 export { prisma };
 
 export function getDateQuery(field, unit, timezone) {
-  const db = getDatabase();
+  const db = getDatabase(process.env.DATABASE_URL);
 
   if (db === POSTGRESQL) {
     if (timezone) {
@@ -61,6 +62,18 @@ export function getDateQuery(field, unit, timezone) {
   }
 }
 
+export function getTimestampInterval(field) {
+  const db = getDatabase(process.env.DATABASE_URL);
+
+  if (db === POSTGRESQL) {
+    return `floor(extract(epoch from max(${field}) - min(${field})))`;
+  }
+
+  if (db === MYSQL) {
+    return `floor(unix_timestamp(max(${field})) - unix_timestamp(min(${field})))`;
+  }
+}
+
 export function getFilterQuery(table, column, filters = {}, params = []) {
   const query = Object.keys(filters).reduce((arr, key) => {
     const filter = filters[key];
@@ -151,7 +164,7 @@ export async function runQuery(query) {
 }
 
 export async function rawQuery(query, params = []) {
-  const db = getDatabase(process.env.DATABASE_URL, process.env.DATABASE_TYPE);
+  const db = getDatabase(process.env.DATABASE_URL);
 
   if (db !== POSTGRESQL && db !== MYSQL) {
     return Promise.reject(new Error('Unknown database.'));