making postgresql "source" its data feed from external csv file ...

 or keeping data processed in a DBMS in synch with local csv file
~
 I kind of like to use a fast in memory DB for coding cycles (either
HSQLDB or H2) and then when I have the need to stress test I use
postgresql, so I keep all my data as csv files which I then "source"
to tables, after running the DDL statements to create them, simply by
going:
~
 SET TABLE "<table_name>" SOURCE "<file_name.csv>;ignore_first=false;"
~
 As I understand postgresql "COPY FROM" does in effect copy the data
to the DBMS, but what I need is for the DBMS to "source" its data feed
with the outer file and synchronize it as it changes without having to
run "COPY TO". Is this possible? This way I can keep the data in a way
that I can try on any DBMS
~
 Is there an equivalent statement in postgresql or some other way to
achieve the same result?
~
 Thanks
 lbrtchx