My additional comments:
tv@fuzzy.cz wrote:
...
For future upgrade, what is the basic steps?
0. Create test database - work out bugs and performance issues before going live.
1. create database
...cluster. You only need to create the individual database if the options you select for the dump do not create the database(s).
2. dump the data from the old database
...using the dump tools from the *new* version. With several cores, you might want to consider using the binary dump options in pg_dump if you want to use the new parallel restore feature in pg_restore with a possible dramatic increase in restore speed (benchmarks I've seen suggest that with 8 cores you may even see an almost 8x restore speedup so it's worth the effort). The manual suggests that setting --jobs to the number of cores on the server is a good first approximation. See the -Fc options on pg_dump and the --jobs option in pg_restore for details.
Cheers,
Steve