Postgresql – Difference between fsync and synchronous_commit – postgresql

To answer your first question.

No, the fsync parameter in postgresql.conf only tells the database that it should write to disk, not how it should do it. According to the documentation:

If this parameter is on, the PostgreSQL server will try to make sure that updates are physically written to disk, by issuing fsync() system calls or various equivalent methods

Which in this case, since you have not changed the wal_sync_method it should choose open_datasync since that is available and the default for Windows platforms.

Also, here I can only speculate:

But seeing that the table is small, and the updates as well, I would guess that you are actually hitting the write-back cache in the hard-drive, which means that you are not writing directly to the disk and therefore the operations are not slowed down due to the writing.

You do not mention what kind of hard drive it is, so it is not possible to know if the cache is write-back, but it sounds like a possible scenario.

They are the same. Check the documentation (where they are mentioned together):

--column-inserts
--attribute-inserts
Dump data as INSERT commands with explicit column names (INSERT INTO table (column, ...) VALUES ...). This will make restoration very slow; it is mainly useful for making dumps that can be loaded into non-PostgreSQL databases. However, since this option generates a separate command for each row, an error in reloading a row causes only that row to be lost rather than the entire table contents.