From: Stephen Frost <sfrost@snowman.net>
> The argument here seems to stem from the idea that issueing a 'TRUNCATE'
> inside the transaction before starting the 'COPY' command is 'too hard'.
> I could be wrong and perhaps opinions will change in the future, but it really
> doesn't seem like the there's much support for adding a new WAL level just to
> avoid doing the TRUNCATE. Appealing to what other database systems
> support can be helpful in some cases but that's usually when we're looking at a
> new capability which multiple other systems have implemented. This isn't
> actually a new capability at all- the WAL level that you're looking for already
> exists and already gives the optimization you're looking for, as long as you issue
> a TRUNCATE at the start of the transaction.
No, we can't ask using TRUNCATE because the user wants to add data to a table.
Regards
Takayuki Tsunakawa