Luke Lonergan said:
> Andrew,
>
>> I will be the first to admit that there are probably some very good
>> possibilities for optimisation of this code. My impression though has
>> been that in almost all cases it's fast enough anyway. I know that on
>> some very modest hardware I have managed to load a 6m row TPC
>> line-items table in just a few minutes. Before we start getting too
>> hung up, I'd be interested to know just how much data people want to
>> load and how fast they want it to be. If people have massive data
>> loads that take hours, days or weeks then it's obviously worth
>> improving if we can. I'm curious to know what size datasets people are
>> really handling this way.
>
> x0+ GB files are common in data warehousing. The issue is often "can
> we load our data within the time allotted for the batch window",
> usually a matter of an hour or two.
>
> Assuming that TPC lineitem is 140Bytes/row, 6M rows in 3 minutes is 4.7
> MB/s. To load a 10GB file at that rate takes about 2/3 hour. If one
> were to restore a 300GB database, it would take 18 hours. Maintenance
> operations are impractical after a few hours, 18 is a non-starter.
>
> In practice, we're usually replacing an Oracle system with PostgreSQL,
> and the load speed difference between the two is currently embarrassing
> and makes the work impractical.
>
OK ... that seems fair enough. The next question is where the data being
loaded comes from? pg_dump? How does load speed compare with using COPY's
binary mode?
cheers
andrew
