PostgreSQL often uses terminology in programs and documentation that is
vague and meaningless to anyone who is new to the system or not familiar
with the implementation. Users are often heard to complain that in
PostgreSQL everything is named differently. We should clean these things
up and in the future think twice before we write something or name
something.
In particular, I have four examples in mind:
"postmaster" is widely used. The term is already confusing to outsiders
because it has nothing to do with the post office. But OK, it's
historical. But note that many users never see a process or executable
called postmaster because it's started automatically or they use pg_ctl,
or they're just using their ODBC client. People tend to know what a
"server" is, so I suggest that term except when you are actually talking
about the executable.
"backend" is often used to mean one of the child processes of the
postmaster. In a general sense, backend is just the same as server, which
is the opposite of client or frontend. Users can't be expected to know
that the server forks subprocesses to do its thing. One of the statistics
access functions is described as "Number of active backends in database".
How does that work? I thought you could only run one postmaster per data
area? -- I think the term "session" is generally clearer, because you
already have session users and these things.
"tuple" is described in one place as "A tuple is an individual state of a
row; each update of a row creates a new tuple for the same logical row."
This definition is inconsistent with common usage -- and even the rest of
the manual.
A "query" is actually only something that retrieves data from a database,
that is, a SELECT statement. UPDATEs are not queries, DELETEs are not
queries, and certainly CREATE TABLE isn't a query. These things are just
statements or commands. Some documentation has this completely mixed up.
Please take these kinds of issues into consideration, as they could make
many users' lifes just slightly easier.
--
Peter Eisentraut peter_e@gmx.net
