Check PHP version.
There are two bugs in PDO_pgsql affecting Drupal:
function checkPHPVersion() {
if (!version_compare(PHP_VERSION, '5.2.11', '>=') || version_compare(PHP_VERSION, '5.3.0', '>=') && !version_compare(PHP_VERSION, '5.3.1', '>=')) {
$this
->fail(st('The version of PHP you are using has known issues with PostgreSQL. You need to upgrade PHP to 5.2.11, 5.3.1 or greater.'));
}
}