Andrew Dunstan wrote:
Florian G. Pflug wrote:
Would it be possible to determine when the copy is starting that
this case holds, and not use the parallel parsing idea in those cases?
In theory, yes. In pratice, I don't want to be the one who has to
answer to an angry user who just suffered a major drop in COPY
performance after adding an ENUM column to his table.
I am yet to be convinced that this is even theoretically a good path
to follow. Any sufficiently large table could probably be partitioned
and then we could use the parallelism that is being discussed for
pg_restore without any modification to the backend at all. Similar
tricks could be played by an external bulk loader for third party data
sources.
I was just floating this as an idea- I don't know enough about the
backend to know if it was a good idea or not, it sounds like "not".
Brian
---------------------------(end of broadcast)---------------------------
TIP 9: In versions below 8.0, the planner will ignore your desire to
choose an index scan if your joining column's datatypes do not
match
