skip large gaps in index

Author: Joe Green

build/db-sync.phar

@@ -23,7 +23,9 @@ class Hash extends HashAbstract {
     protected $where;
 
     protected $total;
-    
+
+    protected $start;
+
     private static $intTypes = array(
         'tinyint',
         'smallint',
@@ -75,11 +77,9 @@ public function setTable($sourcetable, $desttable, $comparisonColumns, $syncColu
             {
                 $this->limitKey = $key;
 
-                $query = 'SELECT %s(' . $this->limitKey . ') FROM ' . $this->sourcetable . ' WHERE 1' . $this->where;
-
-                $this->start = $this->source->fetchOne(sprintf($query, 'MIN'));
+                $this->start = $this->getAggregateCount('MIN');
 
-                $this->total = $this->source->fetchOne(sprintf($query, 'MAX'));
+                $this->total = $this->getAggregateCount('MAX');
 
                 return;
             }
@@ -89,6 +89,20 @@ public function setTable($sourcetable, $desttable, $comparisonColumns, $syncColu
 
         $this->total = $this->source->fetchOne('SELECT count(*) FROM ' . $this->sourcetable . ' WHERE 1' . $this->where);
     }
+
+    private function getAggregateCount($aggregate, $above = null)
+    {
+        $where = '';
+
+        if($above)
+        {
+            $where = ' AND ' .  $this->limitKey . ' >= ' . $this->source->quote($above);
+        }
+
+        $query = 'SELECT %s(' . $this->limitKey . ') FROM ' . $this->sourcetable . ' WHERE 1' . $this->where . $where;
+
+        return $this->source->fetchOne(sprintf($query, $aggregate));
+    }
 
     public function total()
     {
@@ -132,6 +146,11 @@ private function buildComparisonHash()
 
         return "CONCAT(" . implode(',', $str) . ")";
     }
+
+    public function nextValidIndex($block)
+    {
+        return $this->limitKey ? ($this->getAggregateCount('MIN', $block) ?: $block) : $block;
+    }
 
     private function compareLimit($offset, $blockSize)
     {

src/DbSync/Comparison/Hash.php

@@ -48,6 +48,7 @@ public function next()
         if($this->row >= $this->blockSize)
         {
             $this->row = 0;
+
             $this->block += $this->blockSize;
         }
     }
@@ -61,10 +62,15 @@ private function nextBlock()
                 return;
             }
 
-            $this->block += $this->blockSize;
+            $this->block = $this->nextBlockIndex();
         }
     }
 
+    private function nextBlockIndex()
+    {
+        return $this->comparsion->nextValidIndex($this->block + $this->blockSize);
+    }
+
     public function key()
     {
         return $this->block + $this->row;

src/DbSync/Comparison/LimitIterator.php

@@ -63,7 +63,6 @@ function setConnection(PDO $connection)
      */
     public function query($sql, $bind = array())
     {
-
         is_array($bind) or $bind = array($bind);
 
         $stmt = $this->getConnection()->prepare($sql);
@@ -99,6 +98,14 @@ public function fetchNumeric($sql, $bind = array())
         return $this->query($sql, $bind)->fetch(PDO::FETCH_NUM);
     }
 
+    /**
+     *
+     */
+    public function quote($value)
+    {
+        return $this->_connection->quote($value);
+    }
+
     /**
      *
      * @param string $sql