diff --git a/include/mapnik/pool.hpp b/include/mapnik/pool.hpp
index da735bae4..3341da403 100644
--- a/include/mapnik/pool.hpp
+++ b/include/mapnik/pool.hpp
@@ -39,6 +39,7 @@
 #include <map>
 #include <deque>
 #include <ctime>
+#include <cassert>
 
 namespace mapnik
 {
@@ -71,7 +72,7 @@ class Pool : private boost::noncopyable
     typedef std::deque<HolderType> ContType;
 
     Creator<T> creator_;
-    const unsigned initialSize_;
+    unsigned initialSize_;
     unsigned maxSize_;
     ContType usedPool_;
     ContType unusedPool_;
@@ -174,7 +175,38 @@ public:
 #ifdef MAPNIK_THREADSAFE
         mutex::scoped_lock lock(mutex_);
 #endif
-        maxSize_ = size;
+        maxSize_ = std::max(maxSize_,size);
+    }
+
+    unsigned initial_size() const
+    {
+#ifdef MAPNIK_THREADSAFE
+        mutex::scoped_lock lock(mutex_);
+#endif
+        return initialSize_;
+    }
+
+    void set_initial_size(unsigned size)
+    {
+#ifdef MAPNIK_THREADSAFE
+        mutex::scoped_lock lock(mutex_);
+#endif
+        if (size > initialSize_)
+        {
+            initialSize_ = size;
+            unsigned total_size = usedPool_.size() + unusedPool_.size();
+            if (total_size < initialSize_)
+            {
+                unsigned grow_size = initialSize_ - total_size ;
+
+                for (unsigned i=0; i < grow_size; ++i)
+                {
+                    HolderType conn(creator_());
+                    if (conn->isOK())
+                        unusedPool_.push_back(conn);
+                }
+            }
+        }
     }
 };
 
diff --git a/plugins/input/postgis/connection_manager.hpp b/plugins/input/postgis/connection_manager.hpp
index 32bc66d8d..2354da799 100644
--- a/plugins/input/postgis/connection_manager.hpp
+++ b/plugins/input/postgis/connection_manager.hpp
@@ -122,8 +122,8 @@ public:
 
         if (itr != pools_.end())
         {
-            unsigned cur_size = itr->second->max_size();
-            itr->second->set_max_size(std::max(maxSize, cur_size));
+            itr->second->set_max_size(initialSize);
+            itr->second->set_max_size(maxSize);
         }
         else
         {