diff --git a/python/core/qgsvectorlayer.sip b/python/core/qgsvectorlayer.sip
index a1784caa2a11..3a5fbbcfedfd 100644
--- a/python/core/qgsvectorlayer.sip
+++ b/python/core/qgsvectorlayer.sip
@@ -1317,17 +1317,35 @@ class QgsVectorLayer : QgsMapLayer
     /** Caches joined attributes if required (and not already done) */
     void createJoinCaches();
 
-    /** Returns unique values for column
+    /** Calculates a list of unique values contained within an attribute in the layer. Note that
+     * in some circumstances when unsaved changes are present for the layer then the returned list
+     * may contain outdated values (for instance when the attribute value in a saved feature has
+     * been changed inside the edit buffer then the previous saved value will be included in the
+     * returned list).
      * @param index column index for attribute
      * @param uniqueValues out: result list
-     * @param limit maximum number of values to return (-1 if unlimited)
+     * @param limit maximum number of values to return (or -1 if unlimited)
+     * @see minimumValue()
+     * @see maximumValue()
      */
     void uniqueValues( int index, QList<QVariant> &uniqueValues /Out/, int limit = -1 );
 
-    /** Returns minimum value for an attribute column or invalid variant in case of error */
+    /** Returns the minimum value for an attribute column or an invalid variant in case of error.
+     * Note that in some circumstances when unsaved changes are present for the layer then the
+     * returned value may be outdated (for instance when the attribute value in a saved feature has
+     * been changed inside the edit buffer then the previous saved value may be returned as the minimum).
+     * @see maximumValue()
+     * @see uniqueValues()
+     */
     QVariant minimumValue( int index );
 
-    /** Returns maximum value for an attribute column or invalid variant in case of error */
+    /** Returns the maximum value for an attribute column or an invalid variant in case of error.
+     * Note that in some circumstances when unsaved changes are present for the layer then the
+     * returned value may be outdated (for instance when the attribute value in a saved feature has
+     * been changed inside the edit buffer then the previous saved value may be returned as the maximum).
+     * @see minimumValue()
+     * @see uniqueValues()
+     */
     QVariant maximumValue( int index );
 
     /** Calculates an aggregated value from the layer's features.
diff --git a/src/core/qgsvectorlayer.cpp b/src/core/qgsvectorlayer.cpp
index 6149e598c48c..1071b65f479b 100644
--- a/src/core/qgsvectorlayer.cpp
+++ b/src/core/qgsvectorlayer.cpp
@@ -3156,6 +3156,23 @@ void QgsVectorLayer::uniqueValues( int index, QList<QVariant> &uniqueValues, int
           vals << v.toString();
         }
 
+        QgsFeatureMap added = mEditBuffer->addedFeatures();
+        QMapIterator< QgsFeatureId, QgsFeature > addedIt( added );
+        while ( addedIt.hasNext() && ( limit < 0 || uniqueValues.count() < limit ) )
+        {
+          addedIt.next();
+          QVariant v = addedIt.value().attribute( index );
+          if ( v.isValid() )
+          {
+            QString vs = v.toString();
+            if ( !vals.contains( vs ) )
+            {
+              vals << vs;
+              uniqueValues << v;
+            }
+          }
+        }
+
         QMapIterator< QgsFeatureId, QgsAttributeMap > it( mEditBuffer->changedAttributeValues() );
         while ( it.hasNext() && ( limit < 0 || uniqueValues.count() < limit ) )
         {
@@ -3234,7 +3251,35 @@ QVariant QgsVectorLayer::minimumValue( int index )
       return QVariant();
 
     case QgsFields::OriginProvider: //a provider field
-      return mDataProvider->minimumValue( index );
+    {
+      QVariant min = mDataProvider->minimumValue( index );
+      if ( mEditBuffer )
+      {
+        QgsFeatureMap added = mEditBuffer->addedFeatures();
+        QMapIterator< QgsFeatureId, QgsFeature > addedIt( added );
+        while ( addedIt.hasNext() )
+        {
+          addedIt.next();
+          QVariant v = addedIt.value().attribute( index );
+          if ( v.isValid() && qgsVariantLessThan( v, min ) )
+          {
+            min = v;
+          }
+        }
+
+        QMapIterator< QgsFeatureId, QgsAttributeMap > it( mEditBuffer->changedAttributeValues() );
+        while ( it.hasNext() )
+        {
+          it.next();
+          QVariant v = it.value().value( index );
+          if ( v.isValid() && qgsVariantLessThan( v, min ) )
+          {
+            min = v;
+          }
+        }
+      }
+      return min;
+    }
 
     case QgsFields::OriginEdit:
     {
@@ -3293,7 +3338,35 @@ QVariant QgsVectorLayer::maximumValue( int index )
       return QVariant();
 
     case QgsFields::OriginProvider: //a provider field
-      return mDataProvider->maximumValue( index );
+    {
+      QVariant min = mDataProvider->maximumValue( index );
+      if ( mEditBuffer )
+      {
+        QgsFeatureMap added = mEditBuffer->addedFeatures();
+        QMapIterator< QgsFeatureId, QgsFeature > addedIt( added );
+        while ( addedIt.hasNext() )
+        {
+          addedIt.next();
+          QVariant v = addedIt.value().attribute( index );
+          if ( v.isValid() && qgsVariantGreaterThan( v, min ) )
+          {
+            min = v;
+          }
+        }
+
+        QMapIterator< QgsFeatureId, QgsAttributeMap > it( mEditBuffer->changedAttributeValues() );
+        while ( it.hasNext() )
+        {
+          it.next();
+          QVariant v = it.value().value( index );
+          if ( v.isValid() && qgsVariantGreaterThan( v, min ) )
+          {
+            min = v;
+          }
+        }
+      }
+      return min;
+    }
 
     case QgsFields::OriginEdit:
       // the layer is editable, but in certain cases it can still be avoided going through all features
diff --git a/src/core/qgsvectorlayer.h b/src/core/qgsvectorlayer.h
index 0d7c646a9c65..6bad31860e77 100644
--- a/src/core/qgsvectorlayer.h
+++ b/src/core/qgsvectorlayer.h
@@ -1707,17 +1707,35 @@ class CORE_EXPORT QgsVectorLayer : public QgsMapLayer
     /** Caches joined attributes if required (and not already done) */
     void createJoinCaches();
 
-    /** Returns unique values for column
+    /** Calculates a list of unique values contained within an attribute in the layer. Note that
+     * in some circumstances when unsaved changes are present for the layer then the returned list
+     * may contain outdated values (for instance when the attribute value in a saved feature has
+     * been changed inside the edit buffer then the previous saved value will be included in the
+     * returned list).
      * @param index column index for attribute
      * @param uniqueValues out: result list
-     * @param limit maximum number of values to return (-1 if unlimited)
+     * @param limit maximum number of values to return (or -1 if unlimited)
+     * @see minimumValue()
+     * @see maximumValue()
      */
     void uniqueValues( int index, QList<QVariant> &uniqueValues, int limit = -1 );
 
-    /** Returns minimum value for an attribute column or invalid variant in case of error */
+    /** Returns the minimum value for an attribute column or an invalid variant in case of error.
+     * Note that in some circumstances when unsaved changes are present for the layer then the
+     * returned value may be outdated (for instance when the attribute value in a saved feature has
+     * been changed inside the edit buffer then the previous saved value may be returned as the minimum).
+     * @see maximumValue()
+     * @see uniqueValues()
+     */
     QVariant minimumValue( int index );
 
-    /** Returns maximum value for an attribute column or invalid variant in case of error */
+    /** Returns the maximum value for an attribute column or an invalid variant in case of error.
+     * Note that in some circumstances when unsaved changes are present for the layer then the
+     * returned value may be outdated (for instance when the attribute value in a saved feature has
+     * been changed inside the edit buffer then the previous saved value may be returned as the maximum).
+     * @see minimumValue()
+     * @see uniqueValues()
+     */
     QVariant maximumValue( int index );
 
     /** Calculates an aggregated value from the layer's features.