Is PostgreSQL needed ?

[lbelon at etud.insa-tlse.fr]

Hello!

I'm installing Horde-1.3.5  and IMP-2.3.7 .

I've reached the testing part with /horde/test.php .
Everything is OK excepting the PostgreSQL Support.
As the MySQL Support is OK I wonder if I really need to
install PostgreSQL.
I've not understood why there are 2 different Database
Supports.

Could someone answer me and maybe explain me the aim of
PostgreSQL ?

Thanks.