[RFC] Another way to fast reorder table with single SQL query

libraries/joomla/database/driver/postgresql.php

@@ -54,7 +54,7 @@ class JDatabaseDriverPostgresql extends JDatabaseDriver
 	 * @var    string
 	 * @since  12.1
 	 */
-	protected static $dbMinimum = '8.3.18';
+	protected static $dbMinimum = '8.4.2';
 
 	/**
 	 * Operator used for concatenation

libraries/joomla/database/driver/sqlite.php

@@ -55,6 +55,57 @@ public function __destruct()
 		$this->connection = null;
 	}
 
+	/**
+	 * Connects to the database if needed.
+	 *
+	 * @return  void  Returns void if the database connected successfully.
+	 *
+	 * @since   12.1
+	 * @throws  RuntimeException
+	 */
+	public function connect()
+	{
+		if ($this->connection)
+		{
+			return;
+		}
+
+		parent::connect();
+
+		$this->connection->sqliteCreateFunction(
+			'ROW_NUMBER',
+			function($init = null)
+			{
+				static $rownum, $partition;
+
+				if ($init !== null)
+				{
+					$rownum = $init;
+					$partition = null;
+
+					return $rownum;
+				}
+
+				$args = func_get_args();
+				array_shift($args);
+
+				$partitionBy = $args ? implode(',', $args) : null;
+
+				if ($partitionBy === null || $partitionBy === $partition)
+				{
+					$rownum++;
+				}
+				else
+				{
+					$rownum    = 1;
+					$partition = $partitionBy;
+				}
+
+				return $rownum;
+			}
+		);
+	}
+
 	/**
 	 * Disconnects the database.
 	 *

libraries/joomla/database/query.php

@@ -156,6 +156,12 @@ abstract class JDatabaseQuery
 	 */
 	protected $unionAll = null;
 
+	/**
+	 * @var    array  Details of window function.
+	 * @since  __DEPLOY_VERSION__
+	 */
+	protected $selectRowNumber = null;
+
 	/**
 	 * Magic method to provide method alias support for quote() and quoteName().
 	 *
@@ -241,24 +247,27 @@ public function __toString()
 					$query .= (string) $this->where;
 				}
 
-				if ($this->group)
+				if ($this->selectRowNumber === null)
 				{
-					$query .= (string) $this->group;
-				}
+					if ($this->group)
+					{
+						$query .= (string) $this->group;
+					}
 
-				if ($this->having)
-				{
-					$query .= (string) $this->having;
-				}
+					if ($this->having)
+					{
+						$query .= (string) $this->having;
+					}
 
-				if ($this->union)
-				{
-					$query .= (string) $this->union;
-				}
+					if ($this->union)
+					{
+						$query .= (string) $this->union;
+					}
 
-				if ($this->unionAll)
-				{
-					$query .= (string) $this->unionAll;
+					if ($this->unionAll)
+					{
+						$query .= (string) $this->unionAll;
+					}
 				}
 
 				if ($this->order)
@@ -468,6 +477,7 @@ public function clear($clause = null)
 			case 'select':
 				$this->select = null;
 				$this->type = null;
+				$this->selectRowNumber = null;
 				break;
 
 			case 'delete':
@@ -552,6 +562,7 @@ public function clear($clause = null)
 			default:
 				$this->type = null;
 				$this->select = null;
+				$this->selectRowNumber = null;
 				$this->delete = null;
 				$this->update = null;
 				$this->insert = null;
@@ -1817,4 +1828,86 @@ public function findInSet($value, $set)
 	{
 		return "";
 	}
+
+	/**
+	 * Validate arguments which are passed to selectRowNumber method and set up common variables.
+	 *
+	 * @param   string  $orderBy               An expression of ordering for window function.
+	 * @param   string  $orderColumnAlias      An alias for new ordering column.
+	 * @param   string  $partitionBy           An expression of grouping for window function.
+	 * @param   string  $partitionColumnAlias  An alias for calculated grouping column.
+	 *
+	 * @return  void
+	 *
+	 * @since   __DEPLOY_VERSION__
+	 * @throws  RuntimeException
+	 */
+	protected function validateRowNumber($orderBy, $orderColumnAlias, $partitionBy = null, $partitionColumnAlias = null)
+	{
+		if ($this->selectRowNumber)
+		{
+			throw new RuntimeException("Method 'selectRowNumber' can be called only once per instance.");
+		}
+
+		// Required by sqlite
+		if ($partitionBy !== null && $partitionColumnAlias !== null)
+		{
+			if (strpos($partitionBy, ',') !== false)
+			{
+				$this->select($this->concatenate(explode(',', $partitionBy), ',') . ' AS ' . $partitionColumnAlias);
+			}
+			else
+			{
+				$this->select($partitionBy . ' AS ' . $partitionColumnAlias);
+			}
+
+		}
+		else
+		{
+			$this->type = 'select';
+		}
+
+		$this->selectRowNumber = array(
+			'orderBy' => $orderBy,
+			'orderColumnAlias' => $orderColumnAlias,
+			'partitionBy' => $partitionBy,
+			'partitionColumnAlias' => $partitionColumnAlias,
+		);
+	}
+
+	/**
+	 * Return the number of the current row, support for partition, starting from 1
+	 *
+	 * Usage:
+	 * $query->select('id');
+	 * $query->selectRowNumber('ordering,publish_up DESC', 'new_ordering');
+	 * $query->from('#__content');
+	 *
+	 * @param   string  $orderBy               An expression of ordering for window function.
+	 * @param   string  $orderColumnAlias      An alias for new ordering column.
+	 * @param   string  $partitionBy           An expression of grouping for window function.
+	 * @param   string  $partitionColumnAlias  An alias for calculated grouping column.
+	 *
+	 * @return  JDatabaseQuery  Returns this object to allow chaining.
+	 *
+	 * @since   __DEPLOY_VERSION__
+	 * @throws  RuntimeException
+	 */
+	public function selectRowNumber($orderBy, $orderColumnAlias, $partitionBy = null, $partitionColumnAlias = null)
+	{
+		$this->validateRowNumber($orderBy, $orderColumnAlias, $partitionBy, $partitionColumnAlias);
+
+		$column = "ROW_NUMBER() OVER (";
+
+		if ($partitionBy !== null)
+		{
+			$column .= "PARTITION BY $partitionBy ";
+		}
+
+		$column .= "ORDER BY $orderBy) AS $orderColumnAlias";
+
+		$this->select($column);
+
+		return $this;
+	}
 }

libraries/joomla/database/query/mysqli.php

@@ -28,6 +28,52 @@ class JDatabaseQueryMysqli extends JDatabaseQuery implements JDatabaseQueryLimit
 	 */
 	protected $limit;
 
+	/**
+	 * Magic function to convert the query to a string.
+	 *
+	 * @return  string  The completed query.
+	 *
+	 * @since   11.1
+	 */
+	public function __toString()
+	{
+		switch ($this->type)
+		{
+			case 'select':
+				if ($this->selectRowNumber)
+				{
+					$orderBy = $this->selectRowNumber['orderBy'];
+
+					if ($this->selectRowNumber['partitionBy'] !== null && $this->selectRowNumber['partitionColumnAlias'] !== null)
+					{
+						$orderBy = $this->selectRowNumber['partitionBy'] . ',' . $orderBy;
+					}
+
+					$tmpOffset    = $this->offset;
+					$tmpLimit     = $this->limit;
+					$this->offset = 0;
+					$this->limit  = 0;
+					$tmpOrder     = $this->order;
+					$this->order  = new JDatabaseQueryElement('ORDER BY', $orderBy);
+					$query        = parent::__toString();
+					$this->order  = $tmpOrder;
+					$this->offset = $tmpOffset;
+					$this->limit  = $tmpLimit;
+
+					if ($this->offset || $this->limit || $this->order)
+					{
+						// Add support for second order by, offset and limit
+						$query = PHP_EOL . "SELECT * FROM ( " . (string) $query . " ) w" . (string) $this->order;
+						$query = $this->processLimit($query, $this->limit, $this->offset);
+					}
+
+					return $query;
+				}
+		}
+
+		return parent::__toString();
+	}
+
 	/**
 	 * Method to modify a query already in string format with the needed
 	 * additions to make the query limited to a particular number of
@@ -162,4 +208,37 @@ public function findInSet($value, $set)
 	{
 		return " find_in_set(" . $value . ", " . $set . ")";
 	}
+
+	/**
+	 * Return the number of the current row, support for partition, starting from 1
+	 *
+	 * @param   string  $orderBy               An expression of ordering for window function.
+	 * @param   string  $orderColumnAlias      An alias for new ordering column.
+	 * @param   string  $partitionBy           An expression of grouping for window function.
+	 * @param   string  $partitionColumnAlias  An alias for calculated grouping column.
+	 *
+	 * @return  JDatabaseQuery  Returns this object to allow chaining.
+	 *
+	 * @since   __DEPLOY_VERSION__
+	 * @throws  RuntimeException
+	 */
+	public function selectRowNumber($orderBy, $orderColumnAlias, $partitionBy = null, $partitionColumnAlias = null)
+	{
+		$this->validateRowNumber($orderBy, $orderColumnAlias, $partitionBy, $partitionColumnAlias);
+
+		if ($partitionBy !== null && $partitionColumnAlias !== null)
+		{
+			$column = "(SELECT @rownum := IF(@group = CONCAT_WS(',', $partitionBy)"
+				. " OR ((@group := CONCAT_WS(',', $partitionBy)) AND 0), @rownum + 1, 1)"
+				. " FROM (SELECT @rownum := 0, @group := '') AS r) AS $orderColumnAlias";
+		}
+		else
+		{
+			$column = "(SELECT @rownum := @rownum + 1 FROM (SELECT @rownum := 0) AS r) AS $orderColumnAlias";
+		}
+
+		$this->select($column);
+
+		return $this;
+	}
 }

libraries/joomla/database/query/postgresql.php

@@ -83,6 +83,16 @@ public function __toString()
 					$query .= (string) $this->where;
 				}
 
+				if ($this->selectRowNumber)
+				{
+					if ($this->order)
+					{
+						$query .= (string) $this->order;
+					}
+
+					break;
+				}
+
 				if ($this->group)
 				{
 					$query .= (string) $this->group;
@@ -123,23 +133,36 @@ public function __toString()
 
 				if ($this->join)
 				{
-					$onWord = ' ON ';
+					$tmpFrom     = $this->from;
+					$tmpWhere    = $this->where ? clone $this->where : null;
+					$this->from  = null;
 
 					// Workaround for special case of JOIN with UPDATE
 					foreach ($this->join as $join)
 					{
 						$joinElem = $join->getElements();
 
-						$joinArray = explode($onWord, $joinElem[0]);
+						$joinArray = preg_split('/\sON\s/i', $joinElem[0], 2);
 
 						$this->from($joinArray[0]);
-						$this->where($joinArray[1]);
+
+						if (isset($joinArray[1]))
+						{
+							$this->where($joinArray[1]);
+						}
 					}
 
 					$query .= (string) $this->from;
-				}
 
-				if ($this->where)
+					if ($this->where)
+					{
+						$query .= (string) $this->where;
+					}
+
+					$this->from  = $tmpFrom;
+					$this->where = $tmpWhere;
+				}
+				elseif ($this->where)
 				{
 					$query .= (string) $this->where;
 				}