Normally we call this from within our windows program where a lot of code is involved for setting up the environment, and creating the pipes and redirecting stdout, stderr and stdin. However I believe it is the same problem that can be caused with the following commandline in cmd.exe but you will need to have Coreutils for windows installed to get the cat command.
pg_dump.exe -U postgres --format=c mydb | cat > backupfile
The size of the backup doesn't matter. As long as there is atleast one table in the database the warning occurs. When I use --verbose it looks like I get one warning for every table in the database while it is dumping the data in the tables.
Eelke Klein
