Re: Acclerating INSERT/UPDATE using UPS - Mailing list pgsql-hackers

Tom,

Thanks for your comments !
Let me answer to your beneficial mail.

> Indeed, I'm wondering why one needs to hack the Postgres core to throw
> away data integrity guarantees;

The motivation of my work is accelerating INSERT/UPDATE without losing
data integrity guarantees. In the first place, I thought *IF* a
battery supplied memory can be considered as a persistent device,
Sigres method works. However, my assumption seems not to be accepted
unfortunately. Without sending my first email, I could not know your
informative comments. Thank you !

> there are plenty of ways to do that
> already :-(.

Could you please let me know or give me some pointers for the
important information ?
For ubiquitous computing researchers or sensor data processing
researchers, that is a great concern. Since INSERT/UPDATE is too
heavy, several universities have developed stream processing engines
(SPE) which do not store any data. Also I have already published more
than 4 international conference papers in this topic. Moreover, I have
been developing a brand-new DBMS from scratch in my research project.
I am all ears !

> Hideyuki-san has not explained exactly what integrity
> assumptions he wants to make or not make.  I'm surely willing to listen
> to supporting a different set of assumptions than we currently use, but
> I'd like to see a clear explanation of what assumptions are being made
> and why they represent a useful case.

In the first place, I thought Sigres method works *IF* UPSs are
reliable. This was my assumption. However, I am in the process of
understanding that unfortunately UPSs may not be reliable usually
through this discussion :-(   On the other hand, however, there not
negligible people who hopes to dramatically accelerate INSERT/UPDATE
such as financial companies or sensor data processing research groups
such as our team. For example, In our team, the default postgresql is
too slow and thus sensor data insertions delays over an hour. The
purpose of our team is detecting real-world events in real-time, but
it does not work because of bad performance. In such a case, Sigres is
useful if I can believe UPS.
..... I am not confident whether my explanation is clear or not. If
unclear, sorry.

Best Regards,

-- Hideyuki

Tom Lane wrote:
> Gene <genekhart@gmail.com> writes:
>> ... just my two cents. on a side note, would putting the wal on a
>> tmpfs partition give you something similar?
>
> Indeed, I'm wondering why one needs to hack the Postgres core to throw
> away data integrity guarantees; there are plenty of ways to do that
> already :-(.  Hideyuki-san has not explained exactly what integrity
> assumptions he wants to make or not make.  I'm surely willing to listen
> to supporting a different set of assumptions than we currently use, but
> I'd like to see a clear explanation of what assumptions are being made
> and why they represent a useful case.
>
>             regards, tom lane
>
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