> If you watch the speed, you'll see that the insert
> speed is the
> same, but the scan speed is worse (from 32k to 200).
As I said, I don't know a lot about these things.
But I would like someone to comment on this (so that maybe I will know something!):
1) I thought the poor insert performance was due to a "locality of access" in the index creation, hence I thought that
sincethe timestamp is always increasing putting it as first column in the index should give a better insert speed, but
itdidn't: why????
2) I thought that given a query like:
select * from taba where clientid=2 and sensor=4 and timestamp between 'start_t' and 'end_t'
there shouldn't be a huge difference in speed between an index defined as (timestamp, clientid, sensorid) and another
onedefined as (clientid, sensor, timestamp) but I was VERY wrong: it's 1000 times worst. How is it possible???
It's obvious I don't know how multicolumn indexes work...
Can someone explain?
