Steps to reproduce the issue

Download Joomla 4 alpha 1, and try to install.

Expected result

Use Joomla with PostgresSQL

Actual result

Query failed. Logged as notice but fired as error on install.

[Fri May 11 11:15:31.362949 2018] [php7:notice] [pid 10558] [client ::1:47032] PHP Warning:  pg_prepare(): Query failed: ERROR:  no existe la relaci\xc3\xb3n \xc2\xabqa8dk_extensions\xc2\xbb\nL\xc3\x8dNEA 2: FROM "qa8dk_extensions"\n              ^ in public_html/joomla4a1/libraries/vendor/joomla/database/src/Postgresql/PostgresqlDriver.php on line 878
[Fri May 11 11:15:31.363150 2018] [php7:notice] [pid 10558] [client ::1:47032] PHP Stack trace:
[Fri May 11 11:15:31.363191 2018] [php7:notice] [pid 10558] [client ::1:47032] PHP   1. {main}() public_html/joomla4a1/installation/index.php:0
[Fri May 11 11:15:31.363224 2018] [php7:notice] [pid 10558] [client ::1:47032] PHP   2. require_once() public_html/joomla4a1/installation/index.php:30
[Fri May 11 11:15:31.363243 2018] [php7:notice] [pid 10558] [client ::1:47032] PHP   3. Joomla\\CMS\\Installation\\Application\\InstallationApplication->execute() public_html/joomla4a1/installation/includes/app.php:51
[Fri May 11 11:15:31.363262 2018] [php7:notice] [pid 10558] [client ::1:47032] PHP   4. Joomla\\CMS\\Installation\\Application\\InstallationApplication->doExecute() public_html/joomla4a1/installation/src/Application/InstallationApplication.php:234
[Fri May 11 11:15:31.363280 2018] [php7:notice] [pid 10558] [client ::1:47032] PHP   5. Joomla\\CMS\\Installation\\Application\\InstallationApplication->dispatch() public_html/joomla4a1/installation/src/Application/InstallationApplication.php:221
[Fri May 11 11:15:31.363298 2018] [php7:notice] [pid 10558] [client ::1:47032] PHP   6. Joomla\\CMS\\Installation\\Application\\InstallationApplication->executeController() public_html/joomla4a1/installation/src/Application/InstallationApplication.php:192
[Fri May 11 11:15:31.363315 2018] [php7:notice] [pid 10558] [client ::1:47032] PHP   7. Joomla\\CMS\\Installation\\Controller\\DisplayController->execute() public_html/joomla4a1/installation/src/Application/InstallationApplication.php:299
[Fri May 11 11:15:31.363332 2018] [php7:notice] [pid 10558] [client ::1:47032] PHP   8. Joomla\\CMS\\Installation\\Controller\\DisplayController->display() public_html/joomla4a1/libraries/src/MVC/Controller/BaseController.php:710
[Fri May 11 11:15:31.363354 2018] [php7:notice] [pid 10558] [client ::1:47032] PHP   9. Joomla\\CMS\\Installation\\Controller\\DisplayController->display() public_html/joomla4a1/installation/src/Controller/DisplayController.php:83
[Fri May 11 11:15:31.363371 2018] [php7:notice] [pid 10558] [client ::1:47032] PHP  10. Joomla\\CMS\\Installation\\View\\Remove\\HtmlView->display() public_html/joomla4a1/libraries/src/MVC/Controller/BaseController.php:672
[Fri May 11 11:15:31.363388 2018] [php7:notice] [pid 10558] [client ::1:47032] PHP  11. Joomla\\CMS\\Installation\\View\\Remove\\HtmlView->get() public_html/joomla4a1/installation/src/View/Remove/HtmlView.php:36
[Fri May 11 11:15:31.363404 2018] [php7:notice] [pid 10558] [client ::1:47032] PHP  12. Joomla\\CMS\\Installation\\Model\\LanguagesModel->getItems() public_html/joomla4a1/libraries/src/MVC/View/AbstractView.php:144
[Fri May 11 11:15:31.363420 2018] [php7:notice] [pid 10558] [client ::1:47032] PHP  13. Joomla\\Database\\Postgresql\\PostgresqlDriver->setQuery() public_html/joomla4a1/installation/src/Model/LanguagesModel.php:105
[Fri May 11 11:15:31.363436 2018] [php7:notice] [pid 10558] [client ::1:47032] PHP  14. pg_prepare() public_html/joomla4a1/libraries/vendor/joomla/database/src/Postgresql/PostgresqlDriver.php:878

System information (as much as possible)

openSUSE Tumbleweed 20180502
PHP 7.2.4
PostgresSQL 10

Additional comments

I was simply trying to test it locally. In previous Joomla versions I was able to install without problems. All LAMP is downloaded from official repositories.