postgres-xc-general Mailing List for Postgres-XC

Hi Bartlomiej,


On Thu, Sep 12, 2013 at 6:05 AM, Bartłomiej Wójcik <
bar...@tu...> wrote:

> Hello!
>
> I'd like to thanks for Postgres-xc existence!
>
>
> and I have a question:
>
> Is it safely to use it for the production purposes ? Could you tell us
> by whom it is used ?
>


Yes, Postgres-XC is being used in production by our customers and another
one is in the process of testing to deploy soon. I don't have permission to
disclose them.

Feel free to send me a private email if you would like to have a call on
which you can ask me your questions and I can provide general
(non-identifying) info.

Regards,

-- 
Mason Sharp

StormDB - http://www.stormdb.com
The Database Cloud
Postgres-XC Support and Services

On Thu, Sep 12, 2013 at 6:49 AM, Bartłomiej Wójcik <
bar...@tu...> wrote:

> Hello,
>
> When I add every new node to my cluster the performance of the entire
> cluster decreases by 20 percent.
>
> Cluster scheme:
>
> Host1(vm1, IP1, 2core 4GB ram): gtm
> Host2(vm2, IP2, 2core 4GB ram): 1 gtm_proxy + 1 coordinator + 1 datanode
> Host3(vm3, IP3, 2core 4GB ram): 1 gtm_proxy + 1 coordinator + 1 datanode
> Host4(vm4, IP4, 2core 4GB ram): 1 gtm_proxy + 1 coordinator + 1 datanode
>
> I run pgbench (-S) and getting:    ~1200 tps (on each)
>
> when I use (host1 and host2 and host3) the result is: ~1500 tps (on each)
>
> when I use (host 1 and host 2) the result is: ~1800 tps
>
>
> Is this normal behavior ?
>
> All hosts  use the same  disk storage(very large  throughput  ~Gbit/s),
> cores  are not common, ramare not common
>
>
> Regards!
>
>
>
I'm a lurker on the list, but I thought pg-xc was not designed to maximize
transaction rate. Rather its designed for quickly completing a few very
large transactions.

THK


>
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-- 
http://www.keittlab.org/

On Thu, Sep 12, 2013 at 5:19 PM, Bartłomiej Wójcik <
bar...@tu...> wrote:

> Hello,
>
> When I add every new node to my cluster the performance of the entire
> cluster decreases by 20 percent.
>
> Cluster scheme:
>
> Host1(vm1, IP1, 2core 4GB ram): gtm
> Host2(vm2, IP2, 2core 4GB ram): 1 gtm_proxy + 1 coordinator + 1 datanode
> Host3(vm3, IP3, 2core 4GB ram): 1 gtm_proxy + 1 coordinator + 1 datanode
> Host4(vm4, IP4, 2core 4GB ram): 1 gtm_proxy + 1 coordinator + 1 datanode
>
> I run pgbench (-S) and getting:    ~1200 tps (on each)
>
> when I use (host1 and host2 and host3) the result is: ~1500 tps (on each)
>
> when I use (host 1 and host 2) the result is: ~1800 tps
>
>
> Is this normal behavior ?
>

Are you using pgbench supplied with the XC ? If so, AFAIR pgbench has been
modified to distribute the pgbench_accounts table on "bid" field. This was
done to improve pgbench TPCC queries. I can see that it can adversely
affect the -S case though.

Can you try using the pgbench supplied with stock Postgres ? The automatic
distribution will cause the pgbench_accounts table being distributed on the
"aid" which is also the column used in WHERE clause of the select only
queries of -S option. I would expect no performance drop in that case.
Whether you can get a performance improvement with additional nodes will
depend on the workload though. You really want to have a work load which
can not fit your single server. IOW a scale factor such that the entire
pgbench_accounts table does not fit the RAM of a single server will be
appropriate. You would also want to run the test long enough so that shared
buffers are populated with the data.

Thanks,
Pavan

-- 
Pavan Deolasee
http://www.linkedin.com/in/pavandeolasee

Hello,

When I add every new node to my cluster the performance of the entire 
cluster decreases by 20 percent.

Cluster scheme:

Host1(vm1, IP1, 2core 4GB ram): gtm
Host2(vm2, IP2, 2core 4GB ram): 1 gtm_proxy + 1 coordinator + 1 datanode
Host3(vm3, IP3, 2core 4GB ram): 1 gtm_proxy + 1 coordinator + 1 datanode
Host4(vm4, IP4, 2core 4GB ram): 1 gtm_proxy + 1 coordinator + 1 datanode

I run pgbench (-S) and getting:    ~1200 tps (on each)

when I use (host1 and host2 and host3) the result is: ~1500 tps (on each)

when I use (host 1 and host 2) the result is: ~1800 tps


Is this normal behavior ?

All hosts  use the same  disk storage(very large  throughput  ~Gbit/s), cores  are not common, ramare not common


Regards!

Hello!

I'd like to thanks for Postgres-xc existence!


and I have a question:

Is it safely to use it for the production purposes ? Could you tell us 
by whom it is used ?

Best Regards!