Re: Postgres as In-Memory Database?

Hi Edson,

On 2013/11/17 Edson Richter <edsonrichter(at)hotmail(dot)com> you wrote:
> One question: would you please expand your answer and explain how would
this adversely affect async replication?

Is this a question or a hint (or both) :-)? Of course almost all
non-durable settings [1] will delay replication.

I think I have to add, that pure speed of a read-mostly database is the
main scenario I have in mind.
Duration, High-availability and Scaling out are perhaps additional or
separate scenarios.

So, to come back to my question: I think that Postgres could be even faster
by magnitudes, if the assumption of writing to slow secondary storage (like
disks) is removed (or replaced).

--Stefan

[1] http://www.postgresql.org/docs/9.1/static/non-durability.html

2013/11/17 Edson Richter <edsonrichter(at)hotmail(dot)com>

> Em 17/11/2013 10:00, Michael Paquier escreveu:
>
> On Sun, Nov 17, 2013 at 8:25 PM, Stefan Keller <sfkeller(at)gmail(dot)com>
>> wrote:
>>
>>> How can Postgres be used and configured as an In-Memory Database?
>>>
>>> Does anybody know of thoughts or presentations about this "NoSQL
>>> feature" -
>>> beyond e.g. "Perspectives on NoSQL" from Gavin Roy at PGCon 2010)?
>>>
>>> Given, say 128 GB memory or more, and (read-mostly) data that fit's into
>>> this, what are the hints to optimize Postgres (postgresql.conf etc.)?
>>>
>> In this case as you are trading system safety (system will not be
>> crash-safe) for performance... The following parameters would be
>> suited:
>> - Improve performance by reducing the amount of data flushed:
>> fsync = off
>> synchronous_commit=off
>> - Reduce the size of WALs:
>> full_page_writes = off
>> - Disable the background writer:
>> bgwriter_lru_maxpages = 0
>> Regards,
>>
> One question: would you please expand your answer and explain how would
> this adversely affect async replication?
>
> Edson
>
>
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