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<?php

/**

 * @file

 * Database interface code for PostgreSQL database servers.

 */

/**

 * @addtogroup database

 * @{

 */

/**

 * The name by which to obtain a lock for retrive the next insert id.

 */

define('POSTGRESQL_NEXTID_LOCK', 1000);

class DatabaseConnection_pgsql extends DatabaseConnection {

  public function __construct(array $connection_options = array()) {

    // This driver defaults to transaction support, except if explicitly passed FALSE.

    $this->transactionSupport = !isset($connection_options['transactions']) || ($connection_options['transactions'] !== FALSE);

    // Transactional DDL is always available in PostgreSQL,

    // but we'll only enable it if standard transactions are.

    $this->transactionalDDLSupport = $this->transactionSupport;

    // Default to TCP connection on port 5432.

    if (empty($connection_options['port'])) {

      $connection_options['port'] = 5432;

    }

    // PostgreSQL in trust mode doesn't require a password to be supplied.

    if (empty($connection_options['password'])) {

      $connection_options['password'] = NULL;

    }

    // If the password contains a backslash it is treated as an escape character

    // http://bugs.php.net/bug.php?id=53217

    // so backslashes in the password need to be doubled up.

    // The bug was reported against pdo_pgsql 1.0.2, backslashes in passwords

    // will break on this doubling up when the bug is fixed, so check the version

    //elseif (phpversion('pdo_pgsql') < 'version_this_was_fixed_in') {

    else {

      $connection_options['password'] = str_replace('\\', '\\\\', $connection_options['password']);

    }

    $this->connectionOptions = $connection_options;

    $dsn = 'pgsql:host=' . $connection_options['host'] . ' dbname=' . $connection_options['database'] . ' port=' . $connection_options['port'];

    // Allow PDO options to be overridden.

    $connection_options += array(

      'pdo' => array(),

    );

    $connection_options['pdo'] += array(

      // Prepared statements are most effective for performance when queries

      // are recycled (used several times). However, if they are not re-used,

      // prepared statements become ineffecient. Since most of Drupal's

      // prepared queries are not re-used, it should be faster to emulate

      // the preparation than to actually ready statements for re-use. If in

      // doubt, reset to FALSE and measure performance.

      PDO::ATTR_EMULATE_PREPARES => TRUE,

      // Convert numeric values to strings when fetching.

      PDO::ATTR_STRINGIFY_FETCHES => TRUE,

    );

    parent::__construct($dsn, $connection_options['username'], $connection_options['password'], $connection_options['pdo']);

    // Force PostgreSQL to use the UTF-8 character set by default.

    $this->exec("SET NAMES 'UTF8'");

    // Execute PostgreSQL init_commands.

    if (isset($connection_options['init_commands'])) {

      $this->exec(implode('; ', $connection_options['init_commands']));

    }

  }

  public function prepareQuery($query) {

    // mapConditionOperator converts LIKE operations to ILIKE for consistency

    // with MySQL. However, Postgres does not support ILIKE on bytea (blobs)

    // fields.

    // To make the ILIKE operator work, we type-cast bytea fields into text.

    // @todo This workaround only affects bytea fields, but the involved field

    //   types involved in the query are unknown, so there is no way to

    //   conditionally execute this for affected queries only.

    return parent::prepareQuery(preg_replace('/ ([^ ]+) +(I*LIKE|NOT +I*LIKE) /i', ' ${1}::text ${2} ', $query));

  }

  public function query($query, array $args = array(), $options = array()) {

    $options += $this->defaultOptions();

    // The PDO PostgreSQL driver has a bug which

    // doesn't type cast booleans correctly when

    // parameters are bound using associative

    // arrays.

    // See http://bugs.php.net/bug.php?id=48383

    foreach ($args as &$value) {

      if (is_bool($value)) {

        $value = (int) $value;

      }

    }

    try {

      if ($query instanceof DatabaseStatementInterface) {

        $stmt = $query;

        $stmt->execute(NULL, $options);

      }

      else {

        $this->expandArguments($query, $args);

        $stmt = $this->prepareQuery($query);

        $stmt->execute($args, $options);

      }

      switch ($options['return']) {

        case Database::RETURN_STATEMENT:

          return $stmt;

        case Database::RETURN_AFFECTED:

          return $stmt->rowCount();

        case Database::RETURN_INSERT_ID:

          return $this->lastInsertId($options['sequence_name']);

        case Database::RETURN_NULL:

          return;

        default:

          throw new PDOException('Invalid return directive: ' . $options['return']);

      }

    }

    catch (PDOException $e) {

      if ($options['throw_exception']) {

        // Add additional debug information.

        if ($query instanceof DatabaseStatementInterface) {

          $e->query_string = $stmt->getQueryString();

        }

        else {

          $e->query_string = $query;

        }

        $e->args = $args;

        throw $e;

      }

      return NULL;

    }

  }

  public function queryRange($query, $from, $count, array $args = array(), array $options = array()) {

    return $this->query($query . ' LIMIT ' . (int) $count . ' OFFSET ' . (int) $from, $args, $options);

  }

  public function queryTemporary($query, array $args = array(), array $options = array()) {

    $tablename = $this->generateTemporaryTableName();

    $this->query(preg_replace('/^SELECT/i', 'CREATE TEMPORARY TABLE {' . $tablename . '} AS SELECT', $query), $args, $options);

    return $tablename;

  }

  public function driver() {

    return 'pgsql';

  }

  public function databaseType() {

    return 'pgsql';

  }

  public function mapConditionOperator($operator) {

    static $specials;

    // Function calls not allowed in static declarations, thus this method.

    if (!isset($specials)) {

      $specials = array(

        // In PostgreSQL, 'LIKE' is case-sensitive. For case-insensitive LIKE

        // statements, we need to use ILIKE instead.

        'LIKE' => array('operator' => 'ILIKE'),

        'NOT LIKE' => array('operator' => 'NOT ILIKE'),

      );

    }

    return isset($specials[$operator]) ? $specials[$operator] : NULL;

  }

  /**

   * Retrive a the next id in a sequence.

   *

   * PostgreSQL has built in sequences. We'll use these instead of inserting

   * and updating a sequences table.

   */

  public function nextId($existing = 0) {

    // Retrive the name of the sequence. This information cannot be cached

    // because the prefix may change, for example, like it does in simpletests.

    $sequence_name = $this->makeSequenceName('sequences', 'value');

    // When PostgreSQL gets a value too small then it will lock the table,

    // retry the INSERT and if it's still too small then alter the sequence.

    $id = $this->query("SELECT nextval('" . $sequence_name . "')")->fetchField();

    if ($id > $existing) {

      return $id;

    }

    // PostgreSQL advisory locks are simply locks to be used by an

    // application such as Drupal. This will prevent other Drupal proccesses

    // from altering the sequence while we are.

    $this->query("SELECT pg_advisory_lock(" . POSTGRESQL_NEXTID_LOCK . ")");

    // While waiting to obtain the lock, the sequence may have been altered

    // so lets try again to obtain an adequate value.

    $id = $this->query("SELECT nextval('" . $sequence_name . "')")->fetchField();

    if ($id > $existing) {

      $this->query("SELECT pg_advisory_unlock(" . POSTGRESQL_NEXTID_LOCK . ")");

      return $id;

    }

    // Reset the sequence to a higher value than the existing id.

    $this->query("ALTER SEQUENCE " . $sequence_name . " RESTART WITH " . ($existing + 1));

    // Retrive the next id. We know this will be as high as we want it.

    $id = $this->query("SELECT nextval('" . $sequence_name . "')")->fetchField();

    $this->query("SELECT pg_advisory_unlock(" . POSTGRESQL_NEXTID_LOCK . ")");

    return $id;

  }

}

/**

 * @} End of "addtogroup database".

 */