From 5818d0c140cddb0a0292b0644a461f3a970f04e2 Mon Sep 17 00:00:00 2001
From: Joe Green <joe.green@flashtalking.com>
Date: Thu, 15 Jan 2015 17:02:29 +0000
Subject: [PATCH] attempt optimisation

---
 src/DbSync/Comparison/Hash.php | 17 +++++++++++++++--
 tests/integration/config.php   |  2 +-
 2 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/src/DbSync/Comparison/Hash.php b/src/DbSync/Comparison/Hash.php
index bcf699c..d0948f0 100644
--- a/src/DbSync/Comparison/Hash.php
+++ b/src/DbSync/Comparison/Hash.php
@@ -26,6 +26,8 @@ class Hash extends HashAbstract {
 
     protected $start;
 
+    protected $lastComparisonEmpty = false;
+
     private static $intTypes = array(
         'tinyint',
         'smallint',
@@ -149,7 +151,12 @@ private function buildComparisonHash()
 
     public function nextValidIndex($block)
     {
-        return $this->limitKey ? ($this->getAggregateCount('MIN', $block) ?: $block) : $block;
+        if($this->limitKey && $this->lastComparisonEmpty)
+        {
+            return $this->getAggregateCount('MIN', $block) ?: $block;
+        }
+
+        return $block;
     }
     
     private function compareLimit($offset, $blockSize)
@@ -189,7 +196,13 @@ public function compare($offset, $blockSize)
     {      
         $query = $this->limitKey ? $this->compareIndex($offset, $blockSize) : $this->compareLimit($offset, $blockSize);
 
-        if($this->source->fetchOne(sprintf($query,$this->sourcetable)) === $this->destination->fetchOne(sprintf($query,$this->desttable)))
+        $sourceHash = $this->source->fetchOne(sprintf($query,$this->sourcetable));
+
+        $destHash = $this->destination->fetchOne(sprintf($query,$this->desttable));
+
+        $this->lastComparisonEmpty = $sourceHash ? false : true;
+
+        if($sourceHash === $destHash)
         {
             return false;
         }
diff --git a/tests/integration/config.php b/tests/integration/config.php
index 146b94b..4703717 100644
--- a/tests/integration/config.php
+++ b/tests/integration/config.php
@@ -4,7 +4,7 @@
     'host'      => 'localhost',
     'driver'    => 'mysql',
     'username'  => 'root',
-    'password'  => '',
+    'password'  => 'password',
     'charset'   => 'utf8',
     'collation' => 'utf8_unicode_ci',
     'prefix'    => '',