--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/includes/database.pgsql.inc	Tue Dec 23 14:28:28 2008 +0100
@@ -0,0 +1,926 @@
+<?php
+// $Id: database.pgsql.inc,v 1.68.2.1 2008/02/07 10:17:26 goba Exp $
+
+/**
+ * @file
+ * Database interface code for PostgreSQL database servers.
+ */
+
+/**
+ * @ingroup database
+ * @{
+ */
+
+/**
+ * Report database status.
+ */
+function db_status_report() {
+  $t = get_t();
+
+  $version = db_version();
+
+  $form['pgsql'] = array(
+    'title' => $t('PostgreSQL database'),
+    'value' => $version,
+  );
+
+  if (version_compare($version, DRUPAL_MINIMUM_PGSQL) < 0) {
+    $form['pgsql']['severity'] = REQUIREMENT_ERROR;
+    $form['pgsql']['description'] = $t('Your PostgreSQL Server is too old. Drupal requires at least PostgreSQL %version.', array('%version' => DRUPAL_MINIMUM_PGSQL));
+  }
+
+  return $form;
+}
+
+/**
+ * Returns the version of the database server currently in use.
+ *
+ * @return Database server version
+ */
+function db_version() {
+  return db_result(db_query("SHOW SERVER_VERSION"));
+}
+
+/**
+ * Initialize a database connection.
+ */
+function db_connect($url) {
+  // Check if PostgreSQL support is present in PHP
+  if (!function_exists('pg_connect')) {
+    _db_error_page('Unable to use the PostgreSQL database because the PostgreSQL extension for PHP is not installed. Check your <code>php.ini</code> to see how you can enable it.');
+  }
+
+  $url = parse_url($url);
+  $conn_string = '';
+
+  // Decode url-encoded information in the db connection string
+  if (isset($url['user'])) {
+    $conn_string .= ' user='. urldecode($url['user']);
+  }
+  if (isset($url['pass'])) {
+    $conn_string .= ' password='. urldecode($url['pass']);
+  }
+  if (isset($url['host'])) {
+    $conn_string .= ' host='. urldecode($url['host']);
+  }
+  if (isset($url['path'])) {
+    $conn_string .= ' dbname='. substr(urldecode($url['path']), 1);
+  }
+  if (isset($url['port'])) {
+    $conn_string .= ' port='. urldecode($url['port']);
+  }
+
+  // pg_last_error() does not return a useful error message for database
+  // connection errors. We must turn on error tracking to get at a good error
+  // message, which will be stored in $php_errormsg.
+  $track_errors_previous = ini_get('track_errors');
+  ini_set('track_errors', 1);
+
+  $connection = @pg_connect($conn_string);
+  if (!$connection) {
+    require_once './includes/unicode.inc';
+    _db_error_page(decode_entities($php_errormsg));
+  }
+
+  // Restore error tracking setting
+  ini_set('track_errors', $track_errors_previous);
+
+  return $connection;
+}
+
+/**
+ * Runs a basic query in the active database.
+ *
+ * User-supplied arguments to the query should be passed in as separate
+ * parameters so that they can be properly escaped to avoid SQL injection
+ * attacks.
+ *
+ * @param $query
+ *   A string containing an SQL query.
+ * @param ...
+ *   A variable number of arguments which are substituted into the query
+ *   using printf() syntax. Instead of a variable number of query arguments,
+ *   you may also pass a single array containing the query arguments.
+ *
+ *   Valid %-modifiers are: %s, %d, %f, %b (binary data, do not enclose
+ *   in '') and %%.
+ *
+ *   NOTE: using this syntax will cast NULL and FALSE values to decimal 0,
+ *   and TRUE values to decimal 1.
+ *
+ * @return
+ *   A database query result resource, or FALSE if the query was not
+ *   executed correctly.
+ */
+function db_query($query) {
+  $args = func_get_args();
+  array_shift($args);
+  $query = db_prefix_tables($query);
+  if (isset($args[0]) and is_array($args[0])) { // 'All arguments in one array' syntax
+    $args = $args[0];
+  }
+  _db_query_callback($args, TRUE);
+  $query = preg_replace_callback(DB_QUERY_REGEXP, '_db_query_callback', $query);
+  return _db_query($query);
+}
+
+/**
+ * Helper function for db_query().
+ */
+function _db_query($query, $debug = 0) {
+  global $active_db, $last_result, $queries;
+
+  if (variable_get('dev_query', 0)) {
+    list($usec, $sec) = explode(' ', microtime());
+    $timer = (float)$usec + (float)$sec;
+  }
+
+  $last_result = pg_query($active_db, $query);
+
+  if (variable_get('dev_query', 0)) {
+    $bt = debug_backtrace();
+    $query = $bt[2]['function'] ."\n". $query;
+    list($usec, $sec) = explode(' ', microtime());
+    $stop = (float)$usec + (float)$sec;
+    $diff = $stop - $timer;
+    $queries[] = array($query, $diff);
+  }
+
+  if ($debug) {
+    print '<p>query: '. $query .'<br />error:'. pg_last_error($active_db) .'</p>';
+  }
+
+  if ($last_result !== FALSE) {
+    return $last_result;
+  }
+  else {
+    // Indicate to drupal_error_handler that this is a database error.
+    ${DB_ERROR} = TRUE;
+    trigger_error(check_plain(pg_last_error($active_db) ."\nquery: ". $query), E_USER_WARNING);
+    return FALSE;
+  }
+}
+
+/**
+ * Fetch one result row from the previous query as an object.
+ *
+ * @param $result
+ *   A database query result resource, as returned from db_query().
+ * @return
+ *   An object representing the next row of the result, or FALSE. The attributes
+ *   of this object are the table fields selected by the query.
+ */
+function db_fetch_object($result) {
+  if ($result) {
+    return pg_fetch_object($result);
+  }
+}
+
+/**
+ * Fetch one result row from the previous query as an array.
+ *
+ * @param $result
+ *   A database query result resource, as returned from db_query().
+ * @return
+ *   An associative array representing the next row of the result, or FALSE.
+ *   The keys of this object are the names of the table fields selected by the
+ *   query, and the values are the field values for this result row.
+ */
+function db_fetch_array($result) {
+  if ($result) {
+    return pg_fetch_assoc($result);
+  }
+}
+
+/**
+ * Return an individual result field from the previous query.
+ *
+ * Only use this function if exactly one field is being selected; otherwise,
+ * use db_fetch_object() or db_fetch_array().
+ *
+ * @param $result
+ *   A database query result resource, as returned from db_query().
+ * @return
+ *   The resulting field or FALSE.
+ */
+function db_result($result) {
+  if ($result && pg_num_rows($result) > 0) {
+    $array = pg_fetch_row($result);
+    return $array[0];
+  }
+  return FALSE;
+}
+
+/**
+ * Determine whether the previous query caused an error.
+ */
+function db_error() {
+  global $active_db;
+  return pg_last_error($active_db);
+}
+
+/**
+ * Returns the last insert id. This function is thread safe.
+ *
+ * @param $table
+ *   The name of the table you inserted into.
+ * @param $field
+ *   The name of the autoincrement field.
+ */
+function db_last_insert_id($table, $field) {
+  return db_result(db_query("SELECT CURRVAL('{". db_escape_table($table) ."}_". db_escape_table($field) ."_seq')"));
+}
+
+/**
+ * Determine the number of rows changed by the preceding query.
+ */
+function db_affected_rows() {
+  global $last_result;
+  return empty($last_result) ? 0 : pg_affected_rows($last_result);
+}
+
+/**
+ * Runs a limited-range query in the active database.
+ *
+ * Use this as a substitute for db_query() when a subset of the query
+ * is to be returned.
+ * User-supplied arguments to the query should be passed in as separate
+ * parameters so that they can be properly escaped to avoid SQL injection
+ * attacks.
+ *
+ * @param $query
+ *   A string containing an SQL query.
+ * @param ...
+ *   A variable number of arguments which are substituted into the query
+ *   using printf() syntax. Instead of a variable number of query arguments,
+ *   you may also pass a single array containing the query arguments.
+ *   Valid %-modifiers are: %s, %d, %f, %b (binary data, do not enclose
+ *   in '') and %%.
+ *
+ *   NOTE: using this syntax will cast NULL and FALSE values to decimal 0,
+ *   and TRUE values to decimal 1.
+ *
+ * @param $from
+ *   The first result row to return.
+ * @param $count
+ *   The maximum number of result rows to return.
+ * @return
+ *   A database query result resource, or FALSE if the query was not executed
+ *   correctly.
+ */
+function db_query_range($query) {
+  $args = func_get_args();
+  $count = array_pop($args);
+  $from = array_pop($args);
+  array_shift($args);
+
+  $query = db_prefix_tables($query);
+  if (isset($args[0]) and is_array($args[0])) { // 'All arguments in one array' syntax
+    $args = $args[0];
+  }
+  _db_query_callback($args, TRUE);
+  $query = preg_replace_callback(DB_QUERY_REGEXP, '_db_query_callback', $query);
+  $query .= ' LIMIT '. (int)$count .' OFFSET '. (int)$from;
+  return _db_query($query);
+}
+
+/**
+ * Runs a SELECT query and stores its results in a temporary table.
+ *
+ * Use this as a substitute for db_query() when the results need to stored
+ * in a temporary table. Temporary tables exist for the duration of the page
+ * request.
+ * User-supplied arguments to the query should be passed in as separate parameters
+ * so that they can be properly escaped to avoid SQL injection attacks.
+ *
+ * Note that if you need to know how many results were returned, you should do
+ * a SELECT COUNT(*) on the temporary table afterwards. db_affected_rows() does
+ * not give consistent result across different database types in this case.
+ *
+ * @param $query
+ *   A string containing a normal SELECT SQL query.
+ * @param ...
+ *   A variable number of arguments which are substituted into the query
+ *   using printf() syntax. The query arguments can be enclosed in one
+ *   array instead.
+ *   Valid %-modifiers are: %s, %d, %f, %b (binary data, do not enclose
+ *   in '') and %%.
+ *
+ *   NOTE: using this syntax will cast NULL and FALSE values to decimal 0,
+ *   and TRUE values to decimal 1.
+ *
+ * @param $table
+ *   The name of the temporary table to select into. This name will not be
+ *   prefixed as there is no risk of collision.
+ * @return
+ *   A database query result resource, or FALSE if the query was not executed
+ *   correctly.
+ */
+function db_query_temporary($query) {
+  $args = func_get_args();
+  $tablename = array_pop($args);
+  array_shift($args);
+
+  $query = preg_replace('/^SELECT/i', 'CREATE TEMPORARY TABLE '. $tablename .' AS SELECT', db_prefix_tables($query));
+  if (isset($args[0]) and is_array($args[0])) { // 'All arguments in one array' syntax
+    $args = $args[0];
+  }
+  _db_query_callback($args, TRUE);
+  $query = preg_replace_callback(DB_QUERY_REGEXP, '_db_query_callback', $query);
+  return _db_query($query);
+}
+
+/**
+ * Returns a properly formatted Binary Large OBject value.
+ * In case of PostgreSQL encodes data for insert into bytea field.
+ *
+ * @param $data
+ *   Data to encode.
+ * @return
+ *  Encoded data.
+ */
+function db_encode_blob($data) {
+  return "'". pg_escape_bytea($data) ."'";
+}
+
+/**
+ * Returns text from a Binary Large OBject value.
+ * In case of PostgreSQL decodes data after select from bytea field.
+ *
+ * @param $data
+ *   Data to decode.
+ * @return
+ *  Decoded data.
+ */
+function db_decode_blob($data) {
+  return pg_unescape_bytea($data);
+}
+
+/**
+ * Prepare user input for use in a database query, preventing SQL injection attacks.
+ * Note: This function requires PostgreSQL 7.2 or later.
+ */
+function db_escape_string($text) {
+  return pg_escape_string($text);
+}
+
+/**
+ * Lock a table.
+ * This function automatically starts a transaction.
+ */
+function db_lock_table($table) {
+  db_query('BEGIN; LOCK TABLE {'. db_escape_table($table) .'} IN EXCLUSIVE MODE');
+}
+
+/**
+ * Unlock all locked tables.
+ * This function automatically commits a transaction.
+ */
+function db_unlock_tables() {
+  db_query('COMMIT');
+}
+
+/**
+ * Check if a table exists.
+ */
+function db_table_exists($table) {
+  return (bool) db_result(db_query("SELECT COUNT(*) FROM pg_class WHERE relname = '{". db_escape_table($table) ."}'"));
+}
+
+/**
+ * Check if a column exists in the given table.
+ */
+function db_column_exists($table, $column) {
+  return (bool) db_result(db_query("SELECT COUNT(pg_attribute.attname) FROM pg_class, pg_attribute WHERE pg_attribute.attrelid = pg_class.oid AND pg_class.relname = '{". db_escape_table($table) ."}' AND attname = '". db_escape_table($column) ."'"));
+}
+
+/**
+ * Verify if the database is set up correctly.
+ */
+function db_check_setup() {
+  $t = get_t();
+
+  $encoding = db_result(db_query('SHOW server_encoding'));
+  if (!in_array(strtolower($encoding), array('unicode', 'utf8'))) {
+    drupal_set_message($t('Your PostgreSQL database is set up with the wrong character encoding (%encoding). It is possible it will not work as expected. It is advised to recreate it with UTF-8/Unicode encoding. More information can be found in the <a href="@url">PostgreSQL documentation</a>.', array('%encoding' => $encoding, '@url' => 'http://www.postgresql.org/docs/7.4/interactive/multibyte.html')), 'status');
+  }
+}
+
+/**
+ * Wraps the given table.field entry with a DISTINCT(). The wrapper is added to
+ * the SELECT list entry of the given query and the resulting query is returned.
+ * This function only applies the wrapper if a DISTINCT doesn't already exist in
+ * the query.
+ *
+ * @param $table Table containing the field to set as DISTINCT
+ * @param $field Field to set as DISTINCT
+ * @param $query Query to apply the wrapper to
+ * @return SQL query with the DISTINCT wrapper surrounding the given table.field.
+ */
+function db_distinct_field($table, $field, $query) {
+  $field_to_select = 'DISTINCT ON ('. $table .'.'. $field .") $table.$field";
+  // (?<!text) is a negative look-behind (no need to rewrite queries that already use DISTINCT).
+  $query = preg_replace('/(SELECT.*)(?:'. $table .'\.|\s)(?<!DISTINCT\()(?<!DISTINCT\('. $table .'\.)'. $field .'(.*FROM )/AUsi', '\1 '. $field_to_select .'\2', $query);
+  $query = preg_replace('/(ORDER BY )(?!'. $table .'\.'. $field .')/', '\1'."$table.$field, ", $query);
+  return $query;
+}
+
+/**
+ * @} End of "ingroup database".
+ */
+
+/**
+ * @ingroup schemaapi
+ * @{
+ */
+
+/**
+ * This maps a generic data type in combination with its data size
+ * to the engine-specific data type.
+ */
+function db_type_map() {
+  // Put :normal last so it gets preserved by array_flip.  This makes
+  // it much easier for modules (such as schema.module) to map
+  // database types back into schema types.
+  $map = array(
+    'varchar:normal' => 'varchar',
+    'char:normal' => 'character',
+
+    'text:tiny' => 'text',
+    'text:small' => 'text',
+    'text:medium' => 'text',
+    'text:big' => 'text',
+    'text:normal' => 'text',
+
+    'int:tiny' => 'smallint',
+    'int:small' => 'smallint',
+    'int:medium' => 'int',
+    'int:big' => 'bigint',
+    'int:normal' => 'int',
+
+    'float:tiny' => 'real',
+    'float:small' => 'real',
+    'float:medium' => 'real',
+    'float:big' => 'double precision',
+    'float:normal' => 'real',
+
+    'numeric:normal' => 'numeric',
+
+    'blob:big' => 'bytea',
+    'blob:normal' => 'bytea',
+
+    'datetime:normal' => 'timestamp',
+
+    'serial:tiny' => 'serial',
+    'serial:small' => 'serial',
+    'serial:medium' => 'serial',
+    'serial:big' => 'bigserial',
+    'serial:normal' => 'serial',
+  );
+  return $map;
+}
+
+/**
+ * Generate SQL to create a new table from a Drupal schema definition.
+ *
+ * @param $name
+ *   The name of the table to create.
+ * @param $table
+ *   A Schema API table definition array.
+ * @return
+ *   An array of SQL statements to create the table.
+ */
+function db_create_table_sql($name, $table) {
+  $sql_fields = array();
+  foreach ($table['fields'] as $field_name => $field) {
+    $sql_fields[] = _db_create_field_sql($field_name, _db_process_field($field));
+  }
+
+  $sql_keys = array();
+  if (isset($table['primary key']) && is_array($table['primary key'])) {
+    $sql_keys[] = 'PRIMARY KEY ('. implode(', ', $table['primary key']) .')';
+  }
+  if (isset($table['unique keys']) && is_array($table['unique keys'])) {
+    foreach ($table['unique keys'] as $key_name => $key) {
+      $sql_keys[] = 'CONSTRAINT {'. $name .'}_'. $key_name .'_key UNIQUE ('. implode(', ', $key) .')';
+    }
+  }
+
+  $sql = "CREATE TABLE {". $name ."} (\n\t";
+  $sql .= implode(",\n\t", $sql_fields);
+  if (count($sql_keys) > 0) {
+    $sql .= ",\n\t";
+  }
+  $sql .= implode(",\n\t", $sql_keys);
+  $sql .= "\n)";
+  $statements[] = $sql;
+
+  if (isset($table['indexes']) && is_array($table['indexes'])) {
+    foreach ($table['indexes'] as $key_name => $key) {
+      $statements[] = _db_create_index_sql($name, $key_name, $key);
+    }
+  }
+
+  return $statements;
+}
+
+function _db_create_index_sql($table, $name, $fields) {
+  $query = 'CREATE INDEX {'. $table .'}_'. $name .'_idx ON {'. $table .'} (';
+  $query .= _db_create_key_sql($fields) .')';
+  return $query;
+}
+
+function _db_create_key_sql($fields) {
+  $ret = array();
+  foreach ($fields as $field) {
+    if (is_array($field)) {
+      $ret[] = 'substr('. $field[0] .', 1, '. $field[1] .')';
+    }
+    else {
+      $ret[] = $field;
+    }
+  }
+  return implode(', ', $ret);
+}
+
+function _db_create_keys(&$ret, $table, $new_keys) {
+  if (isset($new_keys['primary key'])) {
+    db_add_primary_key($ret, $table, $new_keys['primary key']);
+  }
+  if (isset($new_keys['unique keys'])) {
+    foreach ($new_keys['unique keys'] as $name => $fields) {
+      db_add_unique_key($ret, $table, $name, $fields);
+    }
+  }
+  if (isset($new_keys['indexes'])) {
+    foreach ($new_keys['indexes'] as $name => $fields) {
+      db_add_index($ret, $table, $name, $fields);
+    }
+  }
+}
+
+/**
+ * Set database-engine specific properties for a field.
+ *
+ * @param $field
+ *   A field description array, as specified in the schema documentation.
+ */
+function _db_process_field($field) {
+  if (!isset($field['size'])) {
+    $field['size'] = 'normal';
+  }
+  // Set the correct database-engine specific datatype.
+  if (!isset($field['pgsql_type'])) {
+    $map = db_type_map();
+    $field['pgsql_type'] = $map[$field['type'] .':'. $field['size']];
+  }
+  if ($field['type'] == 'serial') {
+    unset($field['not null']);
+  }
+  return $field;
+}
+
+/**
+ * Create an SQL string for a field to be used in table creation or alteration.
+ *
+ * Before passing a field out of a schema definition into this function it has
+ * to be processed by _db_process_field().
+ *
+ * @param $name
+ *    Name of the field.
+ * @param $spec
+ *    The field specification, as per the schema data structure format.
+ */
+function _db_create_field_sql($name, $spec) {
+  $sql = $name .' '. $spec['pgsql_type'];
+
+  if ($spec['type'] == 'serial') {
+    unset($spec['not null']);
+  }
+  if (!empty($spec['unsigned'])) {
+    if ($spec['type'] == 'serial') {
+      $sql .= " CHECK ($name >= 0)";
+    }
+    else {
+      $sql .= '_unsigned';
+    }
+  }
+
+  if (!empty($spec['length'])) {
+    $sql .= '('. $spec['length'] .')';
+  }
+  elseif (isset($spec['precision']) && isset($spec['scale'])) {
+    $sql .= '('. $spec['precision'] .', '. $spec['scale'] .')';
+  }
+
+  if (isset($spec['not null']) && $spec['not null']) {
+    $sql .= ' NOT NULL';
+  }
+  if (isset($spec['default'])) {
+    $default = is_string($spec['default']) ? "'". $spec['default'] ."'" : $spec['default'];
+    $sql .= " default $default";
+  }
+
+  return $sql;
+}
+
+/**
+ * Rename a table.
+ *
+ * @param $ret
+ *   Array to which query results will be added.
+ * @param $table
+ *   The table to be renamed.
+ * @param $new_name
+ *   The new name for the table.
+ */
+function db_rename_table(&$ret, $table, $new_name) {
+  $ret[] = update_sql('ALTER TABLE {'. $table .'} RENAME TO {'. $new_name .'}');
+}
+
+/**
+ * Drop a table.
+ *
+ * @param $ret
+ *   Array to which query results will be added.
+ * @param $table
+ *   The table to be dropped.
+ */
+function db_drop_table(&$ret, $table) {
+  $ret[] = update_sql('DROP TABLE {'. $table .'}');
+}
+
+/**
+ * Add a new field to a table.
+ *
+ * @param $ret
+ *   Array to which query results will be added.
+ * @param $table
+ *   Name of the table to be altered.
+ * @param $field
+ *   Name of the field to be added.
+ * @param $spec
+ *   The field specification array, as taken from a schema definition.
+ *   The specification may also contain the key 'initial', the newly
+ *   created field will be set to the value of the key in all rows.
+ *   This is most useful for creating NOT NULL columns with no default
+ *   value in existing tables.
+ * @param $keys_new
+ *   Optional keys and indexes specification to be created on the
+ *   table along with adding the field. The format is the same as a
+ *   table specification but without the 'fields' element.  If you are
+ *   adding a type 'serial' field, you MUST specify at least one key
+ *   or index including it in this array. @see db_change_field for more
+ *   explanation why.
+ */
+function db_add_field(&$ret, $table, $field, $spec, $new_keys = array()) {
+  $fixnull = FALSE;
+  if (!empty($spec['not null']) && !isset($spec['default'])) {
+    $fixnull = TRUE;
+    $spec['not null'] = FALSE;
+  }
+  $query = 'ALTER TABLE {'. $table .'} ADD COLUMN ';
+  $query .= _db_create_field_sql($field, _db_process_field($spec));
+  $ret[] = update_sql($query);
+  if (isset($spec['initial'])) {
+    // All this because update_sql does not support %-placeholders.
+    $sql = 'UPDATE {'. $table .'} SET '. $field .' = '. db_type_placeholder($spec['type']);
+    $result = db_query($sql, $spec['initial']);
+    $ret[] = array('success' => $result !== FALSE, 'query' => check_plain($sql .' ('. $spec['initial'] .')'));
+  }
+  if ($fixnull) {
+    $ret[] = update_sql("ALTER TABLE {". $table ."} ALTER $field SET NOT NULL");
+  }
+  if (isset($new_keys)) {
+    _db_create_keys($ret, $table, $new_keys);
+  }
+}
+
+/**
+ * Drop a field.
+ *
+ * @param $ret
+ *   Array to which query results will be added.
+ * @param $table
+ *   The table to be altered.
+ * @param $field
+ *   The field to be dropped.
+ */
+function db_drop_field(&$ret, $table, $field) {
+  $ret[] = update_sql('ALTER TABLE {'. $table .'} DROP COLUMN '. $field);
+}
+
+/**
+ * Set the default value for a field.
+ *
+ * @param $ret
+ *   Array to which query results will be added.
+ * @param $table
+ *   The table to be altered.
+ * @param $field
+ *   The field to be altered.
+ * @param $default
+ *   Default value to be set. NULL for 'default NULL'.
+ */
+function db_field_set_default(&$ret, $table, $field, $default) {
+  if ($default == NULL) {
+    $default = 'NULL';
+  }
+  else {
+    $default = is_string($default) ? "'$default'" : $default;
+  }
+
+  $ret[] = update_sql('ALTER TABLE {'. $table .'} ALTER COLUMN '. $field .' SET DEFAULT '. $default);
+}
+
+/**
+ * Set a field to have no default value.
+ *
+ * @param $ret
+ *   Array to which query results will be added.
+ * @param $table
+ *   The table to be altered.
+ * @param $field
+ *   The field to be altered.
+ */
+function db_field_set_no_default(&$ret, $table, $field) {
+  $ret[] = update_sql('ALTER TABLE {'. $table .'} ALTER COLUMN '. $field .' DROP DEFAULT');
+}
+
+/**
+ * Add a primary key.
+ *
+ * @param $ret
+ *   Array to which query results will be added.
+ * @param $table
+ *   The table to be altered.
+ * @param $fields
+ *   Fields for the primary key.
+ */
+function db_add_primary_key(&$ret, $table, $fields) {
+  $ret[] = update_sql('ALTER TABLE {'. $table .'} ADD PRIMARY KEY ('.
+    implode(',', $fields) .')');
+}
+
+/**
+ * Drop the primary key.
+ *
+ * @param $ret
+ *   Array to which query results will be added.
+ * @param $table
+ *   The table to be altered.
+ */
+function db_drop_primary_key(&$ret, $table) {
+  $ret[] = update_sql('ALTER TABLE {'. $table .'} DROP CONSTRAINT {'. $table .'}_pkey');
+}
+
+/**
+ * Add a unique key.
+ *
+ * @param $ret
+ *   Array to which query results will be added.
+ * @param $table
+ *   The table to be altered.
+ * @param $name
+ *   The name of the key.
+ * @param $fields
+ *   An array of field names.
+ */
+function db_add_unique_key(&$ret, $table, $name, $fields) {
+  $name = '{'. $table .'}_'. $name .'_key';
+  $ret[] = update_sql('ALTER TABLE {'. $table .'} ADD CONSTRAINT '.
+    $name .' UNIQUE ('. implode(',', $fields) .')');
+}
+
+/**
+ * Drop a unique key.
+ *
+ * @param $ret
+ *   Array to which query results will be added.
+ * @param $table
+ *   The table to be altered.
+ * @param $name
+ *   The name of the key.
+ */
+function db_drop_unique_key(&$ret, $table, $name) {
+  $name = '{'. $table .'}_'. $name .'_key';
+  $ret[] = update_sql('ALTER TABLE {'. $table .'} DROP CONSTRAINT '. $name);
+}
+
+/**
+ * Add an index.
+ *
+ * @param $ret
+ *   Array to which query results will be added.
+ * @param $table
+ *   The table to be altered.
+ * @param $name
+ *   The name of the index.
+ * @param $fields
+ *   An array of field names.
+ */
+function db_add_index(&$ret, $table, $name, $fields) {
+  $ret[] = update_sql(_db_create_index_sql($table, $name, $fields));
+}
+
+/**
+ * Drop an index.
+ *
+ * @param $ret
+ *   Array to which query results will be added.
+ * @param $table
+ *   The table to be altered.
+ * @param $name
+ *   The name of the index.
+ */
+function db_drop_index(&$ret, $table, $name) {
+  $name = '{'. $table .'}_'. $name .'_idx';
+  $ret[] = update_sql('DROP INDEX '. $name);
+}
+
+/**
+ * Change a field definition.
+ *
+ * IMPORTANT NOTE: To maintain database portability, you have to explicitly
+ * recreate all indices and primary keys that are using the changed field.
+ *
+ * That means that you have to drop all affected keys and indexes with
+ * db_drop_{primary_key,unique_key,index}() before calling db_change_field().
+ * To recreate the keys and indices, pass the key definitions as the
+ * optional $new_keys argument directly to db_change_field().
+ *
+ * For example, suppose you have:
+ * @code
+ * $schema['foo'] = array(
+ *   'fields' => array(
+ *     'bar' => array('type' => 'int', 'not null' => TRUE)
+ *   ),
+ *   'primary key' => array('bar')
+ * );
+ * @endcode
+ * and you want to change foo.bar to be type serial, leaving it as the
+ * primary key.  The correct sequence is:
+ * @code
+ * db_drop_primary_key($ret, 'foo');
+ * db_change_field($ret, 'foo', 'bar', 'bar',
+ *   array('type' => 'serial', 'not null' => TRUE),
+ *   array('primary key' => array('bar')));
+ * @endcode
+ *
+ * The reasons for this are due to the different database engines:
+ *
+ * On PostgreSQL, changing a field definition involves adding a new field
+ * and dropping an old one which* causes any indices, primary keys and
+ * sequences (from serial-type fields) that use the changed field to be dropped.
+ *
+ * On MySQL, all type 'serial' fields must be part of at least one key
+ * or index as soon as they are created.  You cannot use
+ * db_add_{primary_key,unique_key,index}() for this purpose because
+ * the ALTER TABLE command will fail to add the column without a key
+ * or index specification.  The solution is to use the optional
+ * $new_keys argument to create the key or index at the same time as
+ * field.
+ *
+ * You could use db_add_{primary_key,unique_key,index}() in all cases
+ * unless you are converting a field to be type serial. You can use
+ * the $new_keys argument in all cases.
+ *
+ * @param $ret
+ *   Array to which query results will be added.
+ * @param $table
+ *   Name of the table.
+ * @param $field
+ *   Name of the field to change.
+ * @param $field_new
+ *   New name for the field (set to the same as $field if you don't want to change the name).
+ * @param $spec
+ *   The field specification for the new field.
+ * @param $new_keys
+ *   Optional keys and indexes specification to be created on the
+ *   table along with changing the field. The format is the same as a
+ *   table specification but without the 'fields' element.
+ */
+function db_change_field(&$ret, $table, $field, $field_new, $spec, $new_keys = array()) {
+  $ret[] = update_sql("ALTER TABLE {". $table ."} RENAME $field TO ". $field ."_old");
+  $not_null = isset($spec['not null']) ? $spec['not null'] : FALSE;
+  unset($spec['not null']);
+
+  db_add_field($ret, $table, "$field_new", $spec);
+
+  $ret[] = update_sql("UPDATE {". $table ."} SET $field_new = ". $field ."_old");
+
+  if ($not_null) {
+    $ret[] = update_sql("ALTER TABLE {". $table ."} ALTER $field_new SET NOT NULL");
+  }
+
+  db_drop_field($ret, $table, $field .'_old');
+
+  if (isset($new_keys)) {
+    _db_create_keys($ret, $table, $new_keys);
+  }
+}
+
+/**
+ * @} End of "ingroup schemaapi".
+ */
+