Search Postgresql Archives

Re: Scalability Design Questions

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



OK, this has been very informative and I'd like to thank the three of you. 

Asynchronous replication to readonly slaves is something I will look into.
I've never touched posgtres replication; and Scott mentioned that he was not
familiar with PGCluster, so there must be some other replication system he's
referencing, maybe Slony-I?


Trevor Talbot-2 wrote:
> 
> On 9/8/07, novnov <novnovice@xxxxxxxxx> wrote:
> 
>> But basically, it seems that the answer to one of my questions is that
>> there
>> is currently no way with postgres to spread a single database over
>> multiple
>> servers, ala a loadbalanced apache cluster, where requests are forwarded
>> to
>> different boxes.
> 
> Actually, that's essentially the same thing.  Whether it's the front
> end or middleware, something splits the requests apart before they're
> processed.
> 
> The asynchronous replication to readonly slaves Scott mentioned
> earlier would be roughly equivalent to having several identical apache
> boxes that have their own local copies of files that you periodically
> rsync/ftp/whatever to them from a single place.  Partitioning data
> would be roughly equivalent to having one apache box for images, one
> for ads, etc.
> 
> From what I've seen people mention of RAC, it provides strong
> guarantees about server consistency -- all of them have the changes or
> none of them do -- but you need to go to great effort to achieve the
> same thing on a set of apache boxes too.  I mean, you don't have each
> box accepting file uploads via the web and assume the others will
> magically see the same file at exactly the same time, right?  Unless,
> of course, you're using them purely for CPU reasons and have a single
> shared storage pool.
> 
> Whatever is splitting the requests may do it on a "session" level too,
> which makes it easier for the backend clusters.  E.g. if a given user
> always hits a given apache box, that file upload situation isn't a
> problem as long as you can rsync faster than the sessions time out.
> Often you need to load balance this way anyway if you have a web app
> using an internal notion of sessions -- session data isn't replicated
> to other apache boxes.  (If you need it to be replicated, you're
> already in special design territory, not just easy load balancing.)
> 
> It all varies depending on the details of what you're doing.  Even
> that seemingly straightforward question isn't specific enough :(
> 
> ---------------------------(end of broadcast)---------------------------
> TIP 6: explain analyze is your friend
> 
> 

-- 
View this message in context: http://www.nabble.com/Scalability-Design-Questions-tf4406693.html#a12580273
Sent from the PostgreSQL - general mailing list archive at Nabble.com.


---------------------------(end of broadcast)---------------------------
TIP 6: explain analyze is your friend

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Index of Archives]     [Postgresql Jobs]     [Postgresql Admin]     [Postgresql Performance]     [Linux Clusters]     [PHP Home]     [PHP on Windows]     [Kernel Newbies]     [PHP Classes]     [PHP Books]     [PHP Databases]     [Postgresql & PHP]     [Yosemite]
  Powered by Linux