diff --git a/config/environments/development.js.example b/config/environments/development.js.example
index d36a6ba7..22a66806 100644
--- a/config/environments/development.js.example
+++ b/config/environments/development.js.example
@@ -104,6 +104,7 @@ var config = {
         // by 2 to know how many possible connections will be
         // kept open by the server. The default is 50.
         max: 50,
+        returnToHead: true, // defines the behaviour of the pool: false => queue, true => stack
         idleTimeoutMillis: 1, // idle time before dropping connection
         reapIntervalMillis: 1, // time between cleanups
         slowQueries: {
diff --git a/config/environments/production.js.example b/config/environments/production.js.example
index 7449144d..2a47ea5b 100644
--- a/config/environments/production.js.example
+++ b/config/environments/production.js.example
@@ -98,6 +98,7 @@ var config = {
         // by 2 to know how many possible connections will be
         // kept open by the server. The default is 50.
         max: 50,
+        returnToHead: true, // defines the behaviour of the pool: false => queue, true => stack
         idleTimeoutMillis: 30000, // idle time before dropping connection
         reapIntervalMillis: 1000, // time between cleanups
         slowQueries: {
diff --git a/config/environments/staging.js.example b/config/environments/staging.js.example
index 920388d4..446d5c2f 100644
--- a/config/environments/staging.js.example
+++ b/config/environments/staging.js.example
@@ -98,6 +98,7 @@ var config = {
         // by 2 to know how many possible connections will be
         // kept open by the server. The default is 50.
         max: 50,
+        returnToHead: true, // defines the behaviour of the pool: false => queue, true => stack
         idleTimeoutMillis: 30000, // idle time before dropping connection
         reapIntervalMillis: 1000, // time between cleanups
         slowQueries: {
diff --git a/config/environments/test.js.example b/config/environments/test.js.example
index 68b8f323..9fa7aca8 100644
--- a/config/environments/test.js.example
+++ b/config/environments/test.js.example
@@ -98,6 +98,7 @@ var config = {
         // by 2 to know how many possible connections will be
         // kept open by the server. The default is 50.
         max: 50,
+        returnToHead: true, // defines the behaviour of the pool: false => queue, true => stack
         idleTimeoutMillis: 1, // idle time before dropping connection
         reapIntervalMillis: 1, // time between cleanups
         slowQueries: {