Alberto> 1) Now, i'm not using transaction...
Alberto> So, flush interval is rilevants for my context?

Whether or not you use a transaction, there is always a transaction in the
system and that is what database system revolves around.  If you don't
create one, system creates a temporary one internally!

Flush Interval is to Minimize the disk I/O to accumulate the dirty pages
till 10ms and then flush them all in a single go.  This also helps the user
thread to be more responsive as the main thread is not blocked on finishing
the I/O but rather is delegated to a background thread and the background
thread works at this interval.

Alberto> 2) Now, My app does a compact operation each time starts...
Alberto> But, if default is 60, I dont' need this operation

There is  a difference between Shrink and Compaction.  "Autoshrink
threshold" is about Shrink and Compact does not have any parameters but to
be explicitly invoked.

Assume each page is of 4096 bytes and 16 bytes is reserved for page header.
Now the remaining space is 4080 bytes.

Shrink deals with fragmentation inside a page, like:
Page has 2 rows of sizes 1000 bytes each.  But are not together one after
other, rather they are separated by 1000 bytes.  So, in effect there is a
space of 2080 bytes.  However, if I need to insert a row of 2000 bytes we
can not use this page as 2080 bytes is not continuous.  Shrink deals with
fragmentation in a page.

Compact deals with fragmentation outside a page, like:
Database has 10 pages, out of these let us say 5 pages are occupied and 5
are not.  The free pages are not together, but database system want to have
a colocated space of 5 pages to flush the pages in a single I/O call which
would not be possible with this database state. Compacting database moves
the pages around.

Thanks,
Laxmi