DatabaseSchema/src/handlers/pgsql/writer.php - zetacomponents - Git at Google

 <?php
 /**
  * File containing the ezcDbSchemaPgsqlWriter class.
  *
  * Licensed to the Apache Software Foundation (ASF) under one
  * or more contributor license agreements.  See the NOTICE file
  * distributed with this work for additional information
  * regarding copyright ownership.  The ASF licenses this file
  * to you under the Apache License, Version 2.0 (the
  * "License"); you may not use this file except in compliance
  * with the License.  You may obtain a copy of the License at
  *
  *   http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing,
  * software distributed under the License is distributed on an
  * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
  * KIND, either express or implied.  See the License for the
  * specific language governing permissions and limitations
  * under the License.
  *
  * @package DatabaseSchema
  * @version //autogentag//
  * @license http://www.apache.org/licenses/LICENSE-2.0 Apache License, Version 2.0
  */

 /**
  * Handler for storing database schemas and applying differences that uses PostgreSQL as backend.
  *
  * @package DatabaseSchema
  * @version //autogentag//
  */
 class ezcDbSchemaPgsqlWriter extends ezcDbSchemaCommonSqlWriter implements ezcDbSchemaDbWriter, ezcDbSchemaDiffDbWriter
 {
     /**
      * Contains a type map from DbSchema types to PostgreSQL native types.
      *
      * @var array
      */
     private $typeMap = array(
         'integer' => 'bigint',
         'boolean' => 'boolean',
         'float' => 'double precision',
         'decimal' => 'numeric',
         'date' => 'date',
         'timestamp' => 'timestamp',
         'text' => 'varchar',
         'blob' => 'bytea',
         'clob' => 'text'
     );

     /**
      * Creates tables defined in $dbSchema in the database referenced by $db.
      *
      * If table already exists it will be removed first.
      * This method uses {@link convertToDDL} to create SQL for the schema
      * definition and then executes the return SQL statements on the database
      * handler $db.
      *
      * @todo check for failed transaction
      *
      * @param ezcDbHandler $db
      * @param ezcDbSchema  $dbSchema
      */
     public function saveToDb( ezcDbHandler $db, ezcDbSchema $dbSchema )
     {
         $db->beginTransaction();
         foreach ( $this->convertToDDL( $dbSchema ) as $query )
         {
             if ( $this->isQueryAllowed( $db, $query ) )
             {
                 $db->exec( $query );
             }
             else
             {
                 // workarounds for SQL syntax
                 // "ALTER TABLE tab ALTER col TYPE type"
                 // and "ALTER TABLE tab ADD col type NOT NULL"
                 // that works in PostgreSQL 8.x but not
                 // supported in PostgreSQL 7.x

                 if ( preg_match( "/ALTER TABLE (.*) ALTER (.*) TYPE (.*) USING CAST\((.*)\)/" , $query, $matches ) )
                 {
                     $tableName = $matches[1];
                     $fieldName = $matches[2];
                     $fieldType = $matches[3];
                     $this->changeField( $db, $tableName, $fieldName, $fieldType );
                 }
                 else if ( preg_match( "/ALTER TABLE (.*) ADD (.*) (.*) NOT NULL/" , $query, $matches ) )
                 {
                     $tableName = $matches[1];
                     $fieldName = $matches[2];
                     $fieldType = $matches[3];
                     $this->addField( $db, $tableName, $fieldName, $fieldType );
                 }
             }
         }
         $db->commit();
     }

     /**
      * Checks if certain query allowed.
      *
      * Perform testing if table exist for DROP TABLE query
      * to avoid stoping execution while try to drop not existent table.
      *
      * @param ezcDbHandler $db
      * @param string       $query
      *
      *
      * @return boolean false if query should not be executed.
      */
     public function isQueryAllowed( ezcDbHandler $db, $query )
     {
         if ( substr( $query, 0, 10 ) == 'DROP TABLE' )
         {
             $tableName = trim( substr( $query, strlen( 'DROP TABLE ' ) ), '"' );
             $result = $db->query( "SELECT count(*) FROM pg_tables WHERE tablename='$tableName'" )->fetchAll();
             if ( $result[0]['count'] == 1 )
             {
                 return true;
             }
             else
             {
                 return false;
             }
         }

         if ( preg_match( "/ALTER TABLE (.*) ALTER (.*) TYPE (.*)/" , $query, $matches ) ||
              preg_match( "/ALTER TABLE (.*) ADD (.*) NOT NULL/" , $query, $matches )
            )
         {
             return false;
         }
         return true;
     }

     /**
      * Returns what type of schema difference writer this class implements.
      *
      * This method always returns ezcDbSchema::DATABASE
      *
      * @return int
      */
     public function getDiffWriterType()
     {
         return ezcDbSchema::DATABASE;
     }

     /**
      * Applies the differences defined in $dbSchemaDiff to the database referenced by $db.
      *
      * This method uses {@link convertDiffToDDL} to create SQL for the
      * differences and then executes the returned SQL statements on the
      * database handler $db.
      *
      * @todo check for failed transaction
      *
      * @param ezcDbHandler    $db
      * @param ezcDbSchemaDiff $dbSchemaDiff
      */
     public function applyDiffToDb( ezcDbHandler $db, ezcDbSchemaDiff $dbSchemaDiff )
     {
         $db->beginTransaction();
         foreach ( $this->convertDiffToDDL( $dbSchemaDiff ) as $query )
         {
             if ( $this->isQueryAllowed( $db, $query ) )
             {
                 $db->exec( $query );
             }
             else
             {
                 // workarounds for SQL syntax
                 // "ALTER TABLE tab ALTER col TYPE type"
                 // and "ALTER TABLE tab ADD col type NOT NULL"
                 // that works in PostgreSQL 8.x but not
                 // supported in PostgreSQL 7.x

                 if ( preg_match( "/ALTER TABLE (.*) ALTER (.*) TYPE (.*) USING CAST\((.*)\)/" , $query, $matches ) )
                 {
                     $tableName = trim( $matches[1], '"' );
                     $fieldName = trim( $matches[2], '"' );
                     $fieldType = trim( $matches[3], '"' );
                     $this->changeField( $db, $tableName, $fieldName, $fieldType );
                 }
                 else if ( preg_match( "/ALTER TABLE (.*) ADD (.*) (.*) NOT NULL/" , $query, $matches ) )
                 {
                     $tableName = trim( $matches[1], '"' );
                     $fieldName = trim( $matches[2], '"' );
                     $fieldType = trim( $matches[3], '"' );
                     $this->addField( $db, $tableName, $fieldName, $fieldType );
                 }
             }
         }
         $db->commit();
     }

     /**
      * Returns a "CREATE TABLE" SQL statement part for the table $tableName.
      *
      * @param string  $tableName
      * @return string
      */
     protected function generateCreateTableSqlStatement( $tableName )
     {
         return "CREATE TABLE \"{$tableName}\"";
     }

     /**
      * Performs changing field in PostgreSQL table.
      * ( workaround for "ALTER TABLE table ALTER field TYPE fieldDefinition"
      * that not alowed in PostgreSQL 7.x but works in PostgreSQL 8.x ).
      *
      * @param ezcDbHandler    $db
      * @param string          $tableName
      * @param string          $changeFieldName
      * @param string          $changeFieldType
      *
      */
     private function changeField( ezcDbHandler $db, $tableName, $changeFieldName, $changeFieldType )
     {
         $db->exec( "ALTER TABLE \"{$tableName}\" RENAME COLUMN \"{$changeFieldName}\" TO \"{$changeFieldName}_old\";" );
         $db->exec( "ALTER TABLE \"{$tableName}\" ADD COLUMN \"{$changeFieldName}\" {$changeFieldType};" );
         $db->exec( "UPDATE \"{$tableName}\" SET  \"{$changeFieldName}\" = \"{$changeFieldName}_old\";" );
         $db->exec( "ALTER TABLE \"{$tableName}\" DROP COLUMN \"{$changeFieldName}_old\";" );
     }

     /**
      * Performs adding field in PostgreSQL table.
      * ( workaround for "ALTER TABLE table ADD field fieldDefinition NOT NULL"
      * that not alowed in PostgreSQL 7.x but works in PostgreSQL 8.x ).
      *
      * @param ezcDbHandler    $db
      * @param string          $tableName
      * @param string          $fieldName
      * @param string          $fieldType
      *
      */
     private function addField( ezcDbHandler $db, $tableName, $fieldName, $fieldType )
     {
         $db->exec( "ALTER TABLE \"{$tableName}\" ADD \"{$fieldName}\" {$fieldType}" );
         $db->exec( "ALTER TABLE \"{$tableName}\" ALTER \"{$fieldName}\" SET NOT NULL" );
     }

     /**
      * Returns the differences definition in $dbSchema as database specific SQL DDL queries.
      *
      * @param ezcDbSchemaDiff $dbSchemaDiff
      *
      * @return array(string)
      */
     public function convertDiffToDDL( ezcDbSchemaDiff $dbSchemaDiff )
     {
         $this->diffSchema = $dbSchemaDiff;
         // reset queries
         $this->queries = array();
         $this->context = array();

         $this->generateDiffSchemaAsSql();
         return $this->queries;
     }

     /**
      * Adds a "drop table" query for the table $tableName to the internal list of queries.
      *
      * @param string $tableName
      */
     protected function generateDropTableSql( $tableName )
     {
         $this->queries[] = "DROP TABLE \"$tableName\"";
     }

     /**
      * Converts the generic field type contained in $fieldDefinition to a database specific field definition.
      *
      * @param ezcDbSchemaField $fieldDefinition
      * @return string
      */
     protected function convertFromGenericType( ezcDbSchemaField $fieldDefinition )
     {
         $typeAddition = '';
         if ( in_array( $fieldDefinition->type, array( 'decimal', 'text' ) ) )
         {
             if ( $fieldDefinition->length !== false && $fieldDefinition->length !== 0 )
             {
                 $typeAddition = "({$fieldDefinition->length})";
             }
         }
         if ( $fieldDefinition->type == 'text' && !$fieldDefinition->length )
         {
             $typeAddition = "(255)";
         }

         if ( !isset( $this->typeMap[$fieldDefinition->type] ) )
         {
             throw new ezcDbSchemaUnsupportedTypeException( 'PostGreSQL', $fieldDefinition->type );
         }
         $type = $this->typeMap[$fieldDefinition->type];

         return "$type$typeAddition";
     }

     /**
      * Adds a "create table" query for the table $tableName with
      * definition $tableDefinition to the internal list of queries.
      *
      * @param string           $tableName
      * @param ezcDbSchemaTable $tableDefinition
      */
     protected function generateCreateTableSql( $tableName, ezcDbSchemaTable $tableDefinition )
     {
         $this->context['skip_primary'] = false;
         parent::generateCreateTableSql( $tableName, $tableDefinition );
     }

     /**
      * Generates queries to upgrade a the table $tableName with the differences in $tableDiff.
      *
      * This method generates queries to migrate a table to a new version
      * with the changes that are stored in the $tableDiff property. It
      * will call different subfunctions for the different types of changes, and
      * those functions will add queries to the internal list of queries that is
      * stored in $this->queries.
      *
      * @param string $tableName
      * @param ezcDbSchemaTableDiff $tableDiff
      */
     protected function generateDiffSchemaTableAsSql( $tableName, ezcDbSchemaTableDiff $tableDiff )
     {
         $this->context['skip_primary'] = false;
         parent::generateDiffSchemaTableAsSql( $tableName, $tableDiff );
     }

     /**
      * Adds a "alter table" query to add the field $fieldName to $tableName with the definition $fieldDefinition.
      *
      * @param string           $tableName
      * @param string           $fieldName
      * @param ezcDbSchemaField $fieldDefinition
      */
     protected function generateAddFieldSql( $tableName, $fieldName, ezcDbSchemaField $fieldDefinition )
     {
         $this->queries[] = "ALTER TABLE \"$tableName\" ADD " . $this->generateFieldSql( $fieldName, $fieldDefinition );
     }

     /**
      * Adds a "alter table" query to change the field $fieldName to $tableName with the definition $fieldDefinition.
      *
      * @param string           $tableName
      * @param string           $fieldName
      * @param ezcDbSchemaField $fieldDefinition
      */
     protected function generateChangeFieldSql( $tableName, $fieldName, ezcDbSchemaField $fieldDefinition )
     {
         $fieldType = strstr(  $this->generateFieldSql( $fieldName, $fieldDefinition ), ' ' );
         if ( $fieldDefinition->autoIncrement )
         {
             $this->queries[] = "CREATE SEQUENCE \"{$tableName}_{$fieldName}_seq\"";
             $this->queries[] = "ALTER TABLE \"$tableName\" ALTER \"$fieldName\" TYPE INTEGER";
             $this->queries[] = "ALTER TABLE \"$tableName\" ALTER COLUMN \"$fieldName\" SET DEFAULT nextval('{$tableName}_{$fieldName}_seq')";
             $this->queries[] = "ALTER TABLE \"$tableName\" ALTER COLUMN \"$fieldName\" SET NOT NULL";
         }
         else
         {
             $this->queries[] = "ALTER TABLE \"$tableName\" ALTER \"$fieldName\" TYPE".$fieldType." USING CAST(\"$fieldName\" AS $fieldType)";
         }
     }

     /**
      * Adds a "alter table" query to drop the field $fieldName from $tableName.
      *
      * @param string $tableName
      * @param string $fieldName
      */
     protected function generateDropFieldSql( $tableName, $fieldName )
     {
         $this->queries[] = "ALTER TABLE \"$tableName\" DROP \"$fieldName\"";
     }

     /**
      * Returns a column definition for $fieldName with definition $fieldDefinition.
      *
      * @param  string           $fieldName
      * @param  ezcDbSchemaField $fieldDefinition
      * @return string
      */
     protected function generateFieldSql( $fieldName, ezcDbSchemaField $fieldDefinition )
     {
         $sqlDefinition = "\"$fieldName\" ";

         $defList = array();

         if ( $fieldDefinition->autoIncrement )
         {
             $type = 'serial';
             $defList[] = $type;

             if ( $this->context['skip_primary'] == false )
             {
                 $this->context['skip_primary'] = true;
                 $defList[] = 'PRIMARY KEY';
             }
         }
         else
         {
             $type = $this->convertFromGenericType( $fieldDefinition );
             $defList[] = $type;
         }

         if ( $fieldDefinition->notNull )
         {
             $defList[] = 'NOT NULL';
         }

         if ( !is_null( $fieldDefinition->default ) && !$fieldDefinition->autoIncrement )
         {
             $default = $this->generateDefault( $fieldDefinition->type, $fieldDefinition->default );
             $defList[] = "DEFAULT $default";
         }

         $sqlDefinition .= join( ' ', $defList );

         return $sqlDefinition;
     }

     /**
      * Adds a "alter table" query to add the index $indexName to the table $tableName with definition $indexDefinition to the internal list of queries
      *
      * @param string           $tableName
      * @param string           $indexName
      * @param ezcDbSchemaIndex $indexDefinition
      */
     protected function generateAddIndexSql( $tableName, $indexName, ezcDbSchemaIndex $indexDefinition )
     {

         $sql = "";
         if ( $indexDefinition->primary )
         {
             if ( $this->context['skip_primary'] )
             {
                 return;
             }
             $sql = "ALTER TABLE \"$tableName\" ADD CONSTRAINT \"{$tableName}_pkey\" PRIMARY KEY";
         }
         else if ( $indexDefinition->unique )
         {
             $sql = "CREATE UNIQUE INDEX \"$indexName\" ON \"$tableName\"";
         }
         else
         {
             $sql = "CREATE INDEX \"$indexName\" ON \"$tableName\"";
         }

         $sql .= " ( ";

         $indexFieldSql = array();
         foreach ( $indexDefinition->indexFields as $indexFieldName => $dummy )
         {
                 $indexFieldSql[] = "\"$indexFieldName\"";
         }
         $sql .= join( ', ', $indexFieldSql ) . " )";

         $this->queries[] = $sql;
     }

     /**
      * Adds a "alter table" query to remove the index $indexName from the table $tableName to the internal list of queries.
      *
      * @param string           $tableName
      * @param string           $indexName
      */
     protected function generateDropIndexSql( $tableName, $indexName )
     {
         if ( $indexName == 'primary' ) // handling primary indexes
         {
             $this->queries[] = "ALTER TABLE \"$tableName\" DROP CONSTRAINT {$tableName}_pkey";
         }
         else
         {
             $this->queries[] = "DROP INDEX \"$indexName\"";
         }
     }
 }
 ?>
	<?php
	/**
	* File containing the ezcDbSchemaPgsqlWriter class.
	*
	* Licensed to the Apache Software Foundation (ASF) under one
	* or more contributor license agreements. See the NOTICE file
	* distributed with this work for additional information
	* regarding copyright ownership. The ASF licenses this file
	* to you under the Apache License, Version 2.0 (the
	* "License"); you may not use this file except in compliance
	* with the License. You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing,
	* software distributed under the License is distributed on an
	* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
	* KIND, either express or implied. See the License for the
	* specific language governing permissions and limitations
	* under the License.
	*
	* @package DatabaseSchema
	* @version //autogentag//
	* @license http://www.apache.org/licenses/LICENSE-2.0 Apache License, Version 2.0
	*/

	/**
	* Handler for storing database schemas and applying differences that uses PostgreSQL as backend.
	*
	* @package DatabaseSchema
	* @version //autogentag//
	*/
	class ezcDbSchemaPgsqlWriter extends ezcDbSchemaCommonSqlWriter implements ezcDbSchemaDbWriter, ezcDbSchemaDiffDbWriter
	{
	/**
	* Contains a type map from DbSchema types to PostgreSQL native types.
	*
	* @var array
	*/
	private $typeMap = array(
	'integer' => 'bigint',
	'boolean' => 'boolean',
	'float' => 'double precision',
	'decimal' => 'numeric',
	'date' => 'date',
	'timestamp' => 'timestamp',
	'text' => 'varchar',
	'blob' => 'bytea',
	'clob' => 'text'
	);

	/**
	* Creates tables defined in $dbSchema in the database referenced by $db.
	*
	* If table already exists it will be removed first.
	* This method uses {@link convertToDDL} to create SQL for the schema
	* definition and then executes the return SQL statements on the database
	* handler $db.
	*
	* @todo check for failed transaction
	*
	* @param ezcDbHandler $db
	* @param ezcDbSchema $dbSchema
	*/
	public function saveToDb( ezcDbHandler $db, ezcDbSchema $dbSchema )
	{
	$db->beginTransaction();
	foreach ( $this->convertToDDL( $dbSchema ) as $query )
	{
	if ( $this->isQueryAllowed( $db, $query ) )
	{
	$db->exec( $query );
	}
	else
	{
	// workarounds for SQL syntax
	// "ALTER TABLE tab ALTER col TYPE type"
	// and "ALTER TABLE tab ADD col type NOT NULL"
	// that works in PostgreSQL 8.x but not
	// supported in PostgreSQL 7.x

	if ( preg_match( "/ALTER TABLE (.) ALTER (.) TYPE (.) USING CAST\((.)\)/" , $query, $matches ) )
	{
	$tableName = $matches[1];
	$fieldName = $matches[2];
	$fieldType = $matches[3];
	$this->changeField( $db, $tableName, $fieldName, $fieldType );
	}
	else if ( preg_match( "/ALTER TABLE (.) ADD (.) (.*) NOT NULL/" , $query, $matches ) )
	{
	$tableName = $matches[1];
	$fieldName = $matches[2];
	$fieldType = $matches[3];
	$this->addField( $db, $tableName, $fieldName, $fieldType );
	}
	}
	}
	$db->commit();
	}

	/**
	* Checks if certain query allowed.
	*
	* Perform testing if table exist for DROP TABLE query
	* to avoid stoping execution while try to drop not existent table.
	*
	* @param ezcDbHandler $db
	* @param string $query
	*
	*
	* @return boolean false if query should not be executed.
	*/
	public function isQueryAllowed( ezcDbHandler $db, $query )
	{
	if ( substr( $query, 0, 10 ) == 'DROP TABLE' )
	{
	$tableName = trim( substr( $query, strlen( 'DROP TABLE ' ) ), '"' );
	$result = $db->query( "SELECT count(*) FROM pg_tables WHERE tablename='$tableName'" )->fetchAll();
	if ( $result[0]['count'] == 1 )
	{
	return true;
	}
	else
	{
	return false;
	}
	}

	if ( preg_match( "/ALTER TABLE (.) ALTER (.) TYPE (.*)/" , $query, $matches ) \|\|
	preg_match( "/ALTER TABLE (.) ADD (.) NOT NULL/" , $query, $matches )
	)
	{
	return false;
	}
	return true;
	}

	/**
	* Returns what type of schema difference writer this class implements.
	*
	* This method always returns ezcDbSchema::DATABASE
	*
	* @return int
	*/
	public function getDiffWriterType()
	{
	return ezcDbSchema::DATABASE;
	}

	/**
	* Applies the differences defined in $dbSchemaDiff to the database referenced by $db.
	*
	* This method uses {@link convertDiffToDDL} to create SQL for the
	* differences and then executes the returned SQL statements on the
	* database handler $db.
	*
	* @todo check for failed transaction
	*
	* @param ezcDbHandler $db
	* @param ezcDbSchemaDiff $dbSchemaDiff
	*/
	public function applyDiffToDb( ezcDbHandler $db, ezcDbSchemaDiff $dbSchemaDiff )
	{
	$db->beginTransaction();
	foreach ( $this->convertDiffToDDL( $dbSchemaDiff ) as $query )
	{
	if ( $this->isQueryAllowed( $db, $query ) )
	{
	$db->exec( $query );
	}
	else
	{
	// workarounds for SQL syntax
	// "ALTER TABLE tab ALTER col TYPE type"
	// and "ALTER TABLE tab ADD col type NOT NULL"
	// that works in PostgreSQL 8.x but not
	// supported in PostgreSQL 7.x

	if ( preg_match( "/ALTER TABLE (.) ALTER (.) TYPE (.) USING CAST\((.)\)/" , $query, $matches ) )
	{
	$tableName = trim( $matches[1], '"' );
	$fieldName = trim( $matches[2], '"' );
	$fieldType = trim( $matches[3], '"' );
	$this->changeField( $db, $tableName, $fieldName, $fieldType );
	}
	else if ( preg_match( "/ALTER TABLE (.) ADD (.) (.*) NOT NULL/" , $query, $matches ) )
	{
	$tableName = trim( $matches[1], '"' );
	$fieldName = trim( $matches[2], '"' );
	$fieldType = trim( $matches[3], '"' );
	$this->addField( $db, $tableName, $fieldName, $fieldType );
	}
	}
	}
	$db->commit();
	}

	/**
	* Returns a "CREATE TABLE" SQL statement part for the table $tableName.
	*
	* @param string $tableName
	* @return string
	*/
	protected function generateCreateTableSqlStatement( $tableName )
	{
	return "CREATE TABLE \"{$tableName}\"";
	}

	/**
	* Performs changing field in PostgreSQL table.
	* ( workaround for "ALTER TABLE table ALTER field TYPE fieldDefinition"
	* that not alowed in PostgreSQL 7.x but works in PostgreSQL 8.x ).
	*
	* @param ezcDbHandler $db
	* @param string $tableName
	* @param string $changeFieldName
	* @param string $changeFieldType
	*
	*/
	private function changeField( ezcDbHandler $db, $tableName, $changeFieldName, $changeFieldType )
	{
	$db->exec( "ALTER TABLE \"{$tableName}\" RENAME COLUMN \"{$changeFieldName}\" TO \"{$changeFieldName}_old\";" );
	$db->exec( "ALTER TABLE \"{$tableName}\" ADD COLUMN \"{$changeFieldName}\" {$changeFieldType};" );
	$db->exec( "UPDATE \"{$tableName}\" SET \"{$changeFieldName}\" = \"{$changeFieldName}_old\";" );
	$db->exec( "ALTER TABLE \"{$tableName}\" DROP COLUMN \"{$changeFieldName}_old\";" );
	}

	/**
	* Performs adding field in PostgreSQL table.
	* ( workaround for "ALTER TABLE table ADD field fieldDefinition NOT NULL"
	* that not alowed in PostgreSQL 7.x but works in PostgreSQL 8.x ).
	*
	* @param ezcDbHandler $db
	* @param string $tableName
	* @param string $fieldName
	* @param string $fieldType
	*
	*/
	private function addField( ezcDbHandler $db, $tableName, $fieldName, $fieldType )
	{
	$db->exec( "ALTER TABLE \"{$tableName}\" ADD \"{$fieldName}\" {$fieldType}" );
	$db->exec( "ALTER TABLE \"{$tableName}\" ALTER \"{$fieldName}\" SET NOT NULL" );
	}

	/**
	* Returns the differences definition in $dbSchema as database specific SQL DDL queries.
	*
	* @param ezcDbSchemaDiff $dbSchemaDiff
	*
	* @return array(string)
	*/
	public function convertDiffToDDL( ezcDbSchemaDiff $dbSchemaDiff )
	{
	$this->diffSchema = $dbSchemaDiff;
	// reset queries
	$this->queries = array();
	$this->context = array();

	$this->generateDiffSchemaAsSql();
	return $this->queries;
	}

	/**
	* Adds a "drop table" query for the table $tableName to the internal list of queries.
	*
	* @param string $tableName
	*/
	protected function generateDropTableSql( $tableName )
	{
	$this->queries[] = "DROP TABLE \"$tableName\"";
	}

	/**
	* Converts the generic field type contained in $fieldDefinition to a database specific field definition.
	*
	* @param ezcDbSchemaField $fieldDefinition
	* @return string
	*/
	protected function convertFromGenericType( ezcDbSchemaField $fieldDefinition )
	{
	$typeAddition = '';
	if ( in_array( $fieldDefinition->type, array( 'decimal', 'text' ) ) )
	{
	if ( $fieldDefinition->length !== false && $fieldDefinition->length !== 0 )
	{
	$typeAddition = "({$fieldDefinition->length})";
	}
	}
	if ( $fieldDefinition->type == 'text' && !$fieldDefinition->length )
	{
	$typeAddition = "(255)";
	}

	if ( !isset( $this->typeMap[$fieldDefinition->type] ) )
	{
	throw new ezcDbSchemaUnsupportedTypeException( 'PostGreSQL', $fieldDefinition->type );
	}
	$type = $this->typeMap[$fieldDefinition->type];

	return "$type$typeAddition";
	}

	/**
	* Adds a "create table" query for the table $tableName with
	* definition $tableDefinition to the internal list of queries.
	*
	* @param string $tableName
	* @param ezcDbSchemaTable $tableDefinition
	*/
	protected function generateCreateTableSql( $tableName, ezcDbSchemaTable $tableDefinition )
	{
	$this->context['skip_primary'] = false;
	parent::generateCreateTableSql( $tableName, $tableDefinition );
	}

	/**
	* Generates queries to upgrade a the table $tableName with the differences in $tableDiff.
	*
	* This method generates queries to migrate a table to a new version
	* with the changes that are stored in the $tableDiff property. It
	* will call different subfunctions for the different types of changes, and
	* those functions will add queries to the internal list of queries that is
	* stored in $this->queries.
	*
	* @param string $tableName
	* @param ezcDbSchemaTableDiff $tableDiff
	*/
	protected function generateDiffSchemaTableAsSql( $tableName, ezcDbSchemaTableDiff $tableDiff )
	{
	$this->context['skip_primary'] = false;
	parent::generateDiffSchemaTableAsSql( $tableName, $tableDiff );
	}

	/**
	* Adds a "alter table" query to add the field $fieldName to $tableName with the definition $fieldDefinition.
	*
	* @param string $tableName
	* @param string $fieldName
	* @param ezcDbSchemaField $fieldDefinition
	*/
	protected function generateAddFieldSql( $tableName, $fieldName, ezcDbSchemaField $fieldDefinition )
	{
	$this->queries[] = "ALTER TABLE \"$tableName\" ADD " . $this->generateFieldSql( $fieldName, $fieldDefinition );
	}

	/**
	* Adds a "alter table" query to change the field $fieldName to $tableName with the definition $fieldDefinition.
	*
	* @param string $tableName
	* @param string $fieldName
	* @param ezcDbSchemaField $fieldDefinition
	*/
	protected function generateChangeFieldSql( $tableName, $fieldName, ezcDbSchemaField $fieldDefinition )
	{
	$fieldType = strstr( $this->generateFieldSql( $fieldName, $fieldDefinition ), ' ' );
	if ( $fieldDefinition->autoIncrement )
	{
	$this->queries[] = "CREATE SEQUENCE \"{$tableName}_{$fieldName}_seq\"";
	$this->queries[] = "ALTER TABLE \"$tableName\" ALTER \"$fieldName\" TYPE INTEGER";
	$this->queries[] = "ALTER TABLE \"$tableName\" ALTER COLUMN \"$fieldName\" SET DEFAULT nextval('{$tableName}_{$fieldName}_seq')";
	$this->queries[] = "ALTER TABLE \"$tableName\" ALTER COLUMN \"$fieldName\" SET NOT NULL";
	}
	else
	{
	$this->queries[] = "ALTER TABLE \"$tableName\" ALTER \"$fieldName\" TYPE".$fieldType." USING CAST(\"$fieldName\" AS $fieldType)";
	}
	}

	/**
	* Adds a "alter table" query to drop the field $fieldName from $tableName.
	*
	* @param string $tableName
	* @param string $fieldName
	*/
	protected function generateDropFieldSql( $tableName, $fieldName )
	{
	$this->queries[] = "ALTER TABLE \"$tableName\" DROP \"$fieldName\"";
	}

	/**
	* Returns a column definition for $fieldName with definition $fieldDefinition.
	*
	* @param string $fieldName
	* @param ezcDbSchemaField $fieldDefinition
	* @return string
	*/
	protected function generateFieldSql( $fieldName, ezcDbSchemaField $fieldDefinition )
	{
	$sqlDefinition = "\"$fieldName\" ";

	$defList = array();

	if ( $fieldDefinition->autoIncrement )
	{
	$type = 'serial';
	$defList[] = $type;

	if ( $this->context['skip_primary'] == false )
	{
	$this->context['skip_primary'] = true;
	$defList[] = 'PRIMARY KEY';
	}
	}
	else
	{
	$type = $this->convertFromGenericType( $fieldDefinition );
	$defList[] = $type;
	}

	if ( $fieldDefinition->notNull )
	{
	$defList[] = 'NOT NULL';
	}

	if ( !is_null( $fieldDefinition->default ) && !$fieldDefinition->autoIncrement )
	{
	$default = $this->generateDefault( $fieldDefinition->type, $fieldDefinition->default );
	$defList[] = "DEFAULT $default";
	}

	$sqlDefinition .= join( ' ', $defList );

	return $sqlDefinition;
	}

	/**
	* Adds a "alter table" query to add the index $indexName to the table $tableName with definition $indexDefinition to the internal list of queries
	*
	* @param string $tableName
	* @param string $indexName
	* @param ezcDbSchemaIndex $indexDefinition
	*/
	protected function generateAddIndexSql( $tableName, $indexName, ezcDbSchemaIndex $indexDefinition )
	{

	$sql = "";
	if ( $indexDefinition->primary )
	{
	if ( $this->context['skip_primary'] )
	{
	return;
	}
	$sql = "ALTER TABLE \"$tableName\" ADD CONSTRAINT \"{$tableName}_pkey\" PRIMARY KEY";
	}
	else if ( $indexDefinition->unique )
	{
	$sql = "CREATE UNIQUE INDEX \"$indexName\" ON \"$tableName\"";
	}
	else
	{
	$sql = "CREATE INDEX \"$indexName\" ON \"$tableName\"";
	}

	$sql .= " ( ";

	$indexFieldSql = array();
	foreach ( $indexDefinition->indexFields as $indexFieldName => $dummy )
	{
	$indexFieldSql[] = "\"$indexFieldName\"";
	}
	$sql .= join( ', ', $indexFieldSql ) . " )";

	$this->queries[] = $sql;
	}

	/**
	* Adds a "alter table" query to remove the index $indexName from the table $tableName to the internal list of queries.
	*
	* @param string $tableName
	* @param string $indexName
	*/
	protected function generateDropIndexSql( $tableName, $indexName )
	{
	if ( $indexName == 'primary' ) // handling primary indexes
	{
	$this->queries[] = "ALTER TABLE \"$tableName\" DROP CONSTRAINT {$tableName}_pkey";
	}
	else
	{
	$this->queries[] = "DROP INDEX \"$indexName\"";
	}
	}
	}
	?>