Re: Basic questions before start

Dmitry Tkach wrote:

> gogulus(at)eqnet(dot)hu wrote:
> How are you going to synchronize the databases on the client boxes
> with your 'Master database'?
>
> And how are your clients going to be able to use "some statistical
> data on other clients" when "there is no network connection"? Or did
> you mean that the connection to the "Master database" is down, but the
> clients are still able to talk to each other?
> That would be kinda weir (why would that happen), and still... are you
> planning to have each client to write its statistical data to *all*
> the client databases at once? What will you do if some writes succeed,
> and some fail?

The clients are sell points, working on 50-60.000 of item data like
description, price, quantity unit, etc. This is what I call basic data.
The fill-up is handled at the master db side. There is an application
sitting on the master db which takes care of sending down the data to
each of the clients, and receiving transactions from them.

Clients work on the data, and send back selling information of time,
quantity, discounts, payments, etc. This is overtaken to the master db
for doing calculations there. As the clients can switch with each other
(e.g. sales person can go to an other box), we should know some data on
clients which is somehow machine-independent. That's why some
statistical data of the clients should be synchronized with client
boxes. This is handled by master db as well.

As the clients should be able to work without network connection, they
have to have a local database, and if net connection is on, do the
synchronization with master db. The main idea is, sale cannot stop
because of net connection breakage.

That's why I am asking if 100 Mhz of CPU, 32 Mbytes of RAM can take care
of a database with around 100 tables, 3-4 of these tables having
50-60000 of records, others have at most 1000.

TIA,

Gogulus

>
> ... and also, if you do this, why do you need that 'Master database'
> at all to begin with?
>
> Dima
>
>> Hello,
>>
>> I am planning to implement a system, where there is one Master
>> database running on a Linux box with as many resources as necessary,
>> and there are one or more client pc computers,with processor speed of
>> 100 Mhz, memory of 32-64 Mbytes and a 10Mb/s network card.
>>
>> The major task is that the clients should work on the actual state
>> of data, which means the basic database (data, unchangeable for
>> clients), and some statistical data on other clients, and they should
>> not stop work when there is no network connection to the master pc.
>> They should give back their detailed transactions on the basic data
>> to the master pc.
>>
>> For this reason I consider to run postgres on the client computers,
>> but I am quite concerned about system overhead.
>>
>> The clients will only do basic database work: - selects from the
>> database, without nested selects (or with nested selects with the
>> maximum of 1-2 levels) - writing their transactions into the
>> database, with commit/rollback functionality.
>> - update some tables because of synchronization with master db.
>> - update some tables to summarize the value of transactions. (They
>> could be done by triggers, but if they need resources, there is an
>> existing solution with basic operations).
>>
>> Size of the database: The basic data includes 50-100.000 elements in
>> 3-4 tables each, and much less data in other tables. The number of
>> tables is around 100.
>>
>> I would like to know the opinion of experienced users of Postgres,
>> if I can embark upon this road, or should choose an other way which
>> uses an other db system with lower resource-needs.
>>
>> Thanks in advance,
>>
>> Gogulus
>>
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