>>> "Scott Carey" <scott@richrelevance.com> wrote:
> Note that Write Barriers can be very important for data integrity
when power
> loss or hardware failure are a concern. Only disable them if you
know the
> consequences are mitigated by other factors (such as a BBU + db using
the
> WAL log with sync writes), or if you accept the additional risk to
data
> loss.
For those using xfs, this link may be useful:
http://oss.sgi.com/projects/xfs/faq.html#wcache
> On Temp Tables:
> I am a bit ignorant on the temp table relationship to file creation
-- it
> makes no sense to me at all that a file would even be created for a
temp
> table unless it spills out of RAM or is committed. Inside of a
transaction,
> shouldn't they be purely in-memory if there is space? Is there any
way to
> prevent the file creation? This seems like a total waste of time for
many
> temp table use cases, and explains why they were so slow in some
exploratory
> testing we did a few months ago.
As I learned today, creating a temporary table in PostgreSQL can
easily create four files and do dozens of updates to system tables;
that's all before you start actually inserting any data into the
temporary table.
-Kevin
