Thread: increase insert into local table from remote oracle table preformance

Hi, we probably need more inforation to offer anything useful here, e.g:

- The network bandwidth between the 2 hosts

- the number of partitions on the Postgres end (i.e how many days in 
your case)

- single or batched INSERT

The lack of indexes is probably not going to effect INSERT performance 
that much, but the number of partition tables has a huge impact, so we 
need to know this stuff!

Cheers

Mark


On 14/08/18 08:34, Mariel Cherkassky wrote:
> Hi,
> I'm using postgresql v10.4. I have a local partitioned table (by range 
> - data, every day has its own table). I'm using the oracle_fdw 
> extension to bring data from the oracle partitioned table into my 
> local postgresql (insert into local select * from remote_oracle). 
> Currently, I dont have any indexes on the postgresql`s table. It takes 
> me 10 hours to copy 200G over the network and it is very slow.
> Any recommandations what can I change or improve ?
>
>
> Thanks , Mariel.

Mariel Cherkassky wrote:
> Hi,
> I'm using postgresql v10.4. I have a local partitioned table (by range - data, every day has its own table).
> I'm using the oracle_fdw extension to bring data from the oracle partitioned table into my local postgresql
> (insert into local select * from remote_oracle). Currently, I dont have any indexes on the postgresql`s table.
> It takes me 10 hours to copy 200G over the network and it is very slow.
> Any recommandations what can I change or improve ?

Hard to say anything with so little data.

You could try a bigger value for the "prefetch" option.

One known reason for slow performance is if there are LOBs in the Oracle table.

You could parallelize processing by running several such INSERTs in
parallel, perhaps one per partition, and inserting directly into
the partitions.

Yours,
Laurenz Albe
-- 
Cybertec | https://www.cybertec-postgresql.com

You need to track down your limited resource.  IO, CPU, or network.  I would say it’s unlikely to be CPU, but you never
know. Look at the activities on each server and see what resource is maxed out. My guess is IO, but you could also have
yournetwork choked.   

Sent from my iPad

> On Aug 14, 2018, at 02:12, Laurenz Albe <laurenz.albe@cybertec.at> wrote:
>
> Mariel Cherkassky wrote:
>> Hi,
>> I'm using postgresql v10.4. I have a local partitioned table (by range - data, every day has its own table).
>> I'm using the oracle_fdw extension to bring data from the oracle partitioned table into my local postgresql
>> (insert into local select * from remote_oracle). Currently, I dont have any indexes on the postgresql`s table.
>> It takes me 10 hours to copy 200G over the network and it is very slow.
>> Any recommandations what can I change or improve ?
>
> Hard to say anything with so little data.
>
> You could try a bigger value for the "prefetch" option.
>
> One known reason for slow performance is if there are LOBs in the Oracle table.
>
> You could parallelize processing by running several such INSERTs in
> parallel, perhaps one per partition, and inserting directly into
> the partitions.
>
> Yours,
> Laurenz Albe
> --
> Cybertec | https://www.cybertec-postgresql.com
>