PostgreSQL questions

Dear PostgreSQL novice list,

I am starting development on an application that requires the use of a
Database. I am considering MySQL vs PostgreSQL and have done extensive
(perhaps incomplete) research on both of these.

I have 2 questions about PostgreSQL:
1.) Is there a difference in running PostgreSQL on Windows vs Linux. I
am a Windows user but have a Linux box. For the application I am
leaning more to Linux. Is there advantages or factors I should
consider when choosing the OS?

2.) This question is related to triggers. Can I use a trigger to
notify my external application about a change in the database. I am
looking at using QT for development because of its platform
independence. Thus the complete question is: Can I notify the QT
application that data was added to the database (using a trigger)
without having to query the database the whole time?

The specifications for the application are real-time to semi-real-time
thus I need an OS with semi-real-time characteristics (Windows is not
as far as I know, that is why Linux is a good option). And I want to
notifying the application of changes in the database as soon as they
happen, this will help with the real-time aspect.

Hope I can get this sorted soon as development should start asap.

Thank you,
Carel

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