Zabbix 2 latest data perfomance patch

diff --git a/frontends/php/api/classes/managers/CHistoryManager.php b/frontends/php/api/classes/managers/CHistoryManager.php
index 84a8952..a5c5788 100644
--- a/frontends/php/api/classes/managers/CHistoryManager.php
+++ b/frontends/php/api/classes/managers/CHistoryManager.php
@@ -35,14 +35,27 @@ class CHistoryManager {
    public function getLast(array $items, $limit = 1) {
        $queries = array();
        foreach ($items as $item) {
-           $table = self::getTableName($item['value_type']);
-           $queries[$table][] = DBaddLimit(
-               'SELECT *'.
-               ' FROM '.$table.' h'.
-               ' WHERE h.itemid='.zbx_dbstr($item['itemid']).
-               ' ORDER BY h.clock DESC',
-               $limit
-           );
+           $table = self::getTableNameForPartitioning($item['value_type']);
+
+           if (isset($item['delay'])) {
+               $period = time() - ( $item['delay'] * LATEST_DATA_MULTIPLIER );
+               $queries[$table][] = DBaddLimit(
+                   'SELECT *'.
+                   ' FROM '.$table.' h'.
+                   ' WHERE h.itemid='.zbx_dbstr($item['itemid']).
+                   ' AND h.clock > '.$period.
+                   ' ORDER BY h.clock DESC',
+                   $limit
+               );
+           } else {
+                                $queries[$table][] = DBaddLimit(
+                                        'SELECT *'.
+                                        ' FROM '.$table.' h'.
+                                        ' WHERE h.itemid='.zbx_dbstr($item['itemid']).
+                                        ' ORDER BY h.clock DESC',
+                                        $limit
+               );
+           }
        }

        $rs = array();
@@ -75,4 +88,33 @@ class CHistoryManager {
        return $tables[$valueType];
    }

+   /**
+   * Return the name of the partitioned table where the data for the given value type is stored.
+   *
+   * @param int $valueType
+   *
+   * @return string
+   */
+   private static function getTableNameForPartitioning($valueType) {
+       // Is this table define in partitioned tables?
+       if (strripos( PARTITION_TABLES_DAILY, '"'.self::getTableName($valueType).'"' )) {
+           // Is partitions schema and partition dateformat defined?
+           if (PARTITION_DATEFORMAT > "" and PARTITION_SCHEMA > "") {
+
+               // If tables parted with unix timestamp (first second for each day)
+               if (PARTITION_DATEFORMAT == 'U') {
+                                   $nowdt= mktime( 0,0,0,date( "m",time() ),date( "d",time() ),date("y",time() ) );
+                   return PARTITION_SCHEMA.'.'.self::getTableName($valueType).PARTITION_DATE_PREFIX.date(PARTITION_DATEFORMAT, $nowdt);
+
+                           // For partitioning by current date (current day, current month, etc.)
+                           } else {
+                   return $table_part = PARTITION_SCHEMA.'.'.self::getTableName($valueType).PARTITION_DATE_PREFIX.date(PARTITION_DATEFORMAT);
+               }
+           }
+       }
+
+       // Default: return normal table name
+       return self::getTableName($valueType);
+   }
+
 }
diff --git a/frontends/php/include/defines.inc.php b/frontends/php/include/defines.inc.php
index 3d851a7..78569ef 100644
--- a/frontends/php/include/defines.inc.php
+++ b/frontends/php/include/defines.inc.php
@@ -991,3 +991,14 @@ ini_set('precision', 14);
 if (function_exists('bcscale')) {
    bcscale(7);
 }
+
+// partitions.history_uint_p2013_01_02
+// |          |           | \ PARTITION_DATEFORMAT
+// |          |           \ PARTITION_DATE_PREFIX
+// |          \ normal table name
+// \ PARTITION_SCHEMA
+define('PARTITION_SCHEMA', 'partitions');
+define('PARTITION_TABLES_DAILY', '"history" "history_log" "history_str" "history_text" "history_uint"');
+define('PARTITION_DATE_PREFIX', '_p');
+define('PARTITION_DATEFORMAT', 'Y_m_d');
+define('LATEST_DATA_MULTIPLIER', 3);
diff --git a/frontends/php/latest.php b/frontends/php/latest.php
index ec2f68b..5f5565e 100644
--- a/frontends/php/latest.php
+++ b/frontends/php/latest.php
@@ -258,7 +258,7 @@ CArrayHelper::sort($applications, $sortFields);

 // fetch items and data
 $allItems = DBfetchArray(DBselect(
-   'SELECT DISTINCT i.hostid,i.itemid,i.name,i.value_type,i.units,i.state,i.valuemapid,i.key_,ia.applicationid'.
+   'SELECT DISTINCT i.hostid,i.itemid,i.name,i.value_type,i.units,i.state,i.valuemapid,i.key_,ia.applicationid,i.delay'.
    ' FROM items i '.
        ' LEFT JOIN items_applications ia ON ia.itemid=i.itemid'.
    ' WHERE i.status='.ITEM_STATUS_ACTIVE.