Re: Why insertion throughput can be reduced with an increase of batch size?

On 08/22/2016 11:49 PM, Павел Филонов wrote:

Please reply to list also.
Ccing list

>
>
> 2016-08-23 4:02 GMT+03:00 Adrian Klaver <adrian(dot)klaver(at)aklaver(dot)com
> <mailto:adrian(dot)klaver(at)aklaver(dot)com>>:
>
> On 08/21/2016 11:53 PM, Павел Филонов wrote:
>
> My greetings to everybody!
>
> I recently faced with the observation which I can not explain. Why
> insertion throughput can be reduced with an increase of batch size?
>
> Brief description of the experiment.
>
> * PostgreSQL 9.5.4 as server
> * https://github.com/sfackler/rust-postgres
> <https://github.com/sfackler/rust-postgres> library as client driver
> * one relation with two indices (scheme in attach)
>
> Experiment steps:
>
> * populate DB with 259200000 random records
> * start insertion for 60 seconds with one client thread and
> batch size = m
> * record insertions per second (ips) in clients code
>
> Plot median ips from m for m in [2^0, 2^1, ..., 2^15] (in
> attachment).
>
>
> On figure with can see that from m = 128 to m = 256 throughput
> have been
> reduced from 13 000 ips to 5000.
>
> I hope someone can help me understand what is the reason for
> such behavior?
>
>
> To add to Jeff's questions:
>
> You say you are measuring the IPS in the clients code.
>
> Where is the client, on the same machine, same network or remote
> network?
>
>
> Postgres runs in docker and client runs on the host machine. Client
> connects to localhost interface.

I don't use Docker so I have no insights here.

>
>
> --
> Best regards
> Filonov Pavel
>
>
>
>
>
> --
> Adrian Klaver
> adrian(dot)klaver(at)aklaver(dot)com <mailto:adrian(dot)klaver(at)aklaver(dot)com>
>
>
>
>
> --
> С наилучшими пожеланиями,
> Филонов Павел

--
Adrian Klaver
adrian(dot)klaver(at)aklaver(dot)com