If you want to use typo3 with postgreSQL-database you have to use the AdoDB-abstraction layer between them. AdoDB makes the typo3 commands database-independent. However, it requires some compatibility configuration in postgreSQL.
If you created a new postgreSQL database, you must run the following sql commands:
#compatibility modifications (create new functions, modify existent functions) psql -U <Username> -d <myDatabase> < /typo3_src-7.6.15/typo3/sysext/res/postgresql/postgresql-compatibility.sql
If you don’t run this command, you will get adoDB-error messages like “function not found” and so on.