Re: embeding postgre

Hi,

I have a question, because i cannot find any information in online docs
(maybe i'm just blind :P).
I'm want to build application with embedded database, but i also need a
possibility to have one global database, which can be accessed from internet
(ability to synchronize between remote and local/embedded database). I heard
from somone that i could use PostgreSQL, but I cannot find any information
that confirms or denies it. And one more thing, i'm interested only in free
solution ;).
Sorry for if i made some mistakes, english is not my native language.

I'll be appreciate for any information.

On Fri, 20 Feb 2004, twosk wrote:

> Hi,
>
> I have a question, because i cannot find any information in online docs
> (maybe i'm just blind :P).
> I'm want to build application with embedded database, but i also need a
> possibility to have one global database, which can be accessed from internet
> (ability to synchronize between remote and local/embedded database). I heard
> from somone that i could use PostgreSQL, but I cannot find any information
> that confirms or denies it. And one more thing, i'm interested only in free
> solution ;).
> Sorry for if i made some mistakes, english is not my native language.
>
> I'll be appreciate for any information.

You should probably consider either firebird if you need a "real" database
with locking real transactions and all that, or sqllite if all you need is
a nice fast single user database with a sql interface.

Postgresql is really not suited to embedded applications.

Of course, in 50 years, when embedded applications are running on Star
Trek technology, and Postgresql is a quaint old thing, it might make
sense, but today, most embedded devices having memory in the hundreds of
megabytes designed to have only a few hundred thousand writes to each
memory cell, it's just not a good choice.

twosk(at)interia(dot)pl ("twosk") writes:
> I have a question, because i cannot find any information in online docs
> (maybe i'm just blind :P).
> I'm want to build application with embedded database, but i also need a
> possibility to have one global database, which can be accessed from internet
> (ability to synchronize between remote and local/embedded database). I heard
> from somone that i could use PostgreSQL, but I cannot find any information
> that confirms or denies it. And one more thing, i'm interested only in free
> solution ;).

When people come looking to run PostgreSQL as an 'embedded library,'
embedded inside the application process, they generally get rebuffed,
as this heads in exactly the opposite direction to the design of
PostgreSQL.

It _is_ possible to run PostgreSQL in a "somewhat embedded" mode,
where you embed _control_ over that database fairly deeply into your
application. It runs as a separate process, which would mean you
would retain various capabilities for "network" access.

But few have gotten really interested in that; we usually have other
"fish to fry."

You would presumably need to explain in more detail what you intend,
although there is a concommittant danger that you may specify your own
implementation assumptions as requirements, and prevent there from
being answers.

Be prepared to say "Here's what I anticipate," and risk being
contradicted :-).
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Centuries ago, Nostradamus foresaw when scott(dot)marlowe(at)ihs(dot)com ("scott.marlowe") would write:
> Postgresql is really not suited to embedded applications.

Counterpoint: People tend to think about "embedded" in one of two
ways:

1. Applications using PICs and memory devices with _really_ limited
lifetimes, where the RIGHT answer is probably something like
Sleepycat DB, or perhaps, for persistent data, DJB's "constant
database" (cdb).

Relational systems Need Not Apply; the implementation language
is liable to be one of [8051 assembler|C|Forth], and even SQLite
is likely to be way too big.

This sort of gentle programmer should order Leo Brodie's book
_Thinking Forth_, and see how Forth BLOCKs may be used as a
virtual memory 'database.'

2. They have megabytes of memory, lots of room for the GUI fluff
that they're doing, and want a database that isn't really
'getting in their way.'

In this sort of case, MySQL and SQLite and Firebird propose the
answer that you can "link them in" to your application, and
thereby have data storage embedded in the application.

PostgreSQL is designed in a manner that actively discourages
that particular approach; it wants there to be a separate
"postmaster" process. But I am unconvinced that this means you
_can't_ design the application in a manner where PostgreSQL can
hide alongside, and still "stay mostly out of the way."

Indeed, the fact that PostgreSQL runs as a separate process
seems to me to be an excellent way of "staying out of the way."
In contrast, the need, with "embedded in the same process"
systems, to have things like event loops and the need to start
up the database within your application is anything but "staying
out of the way."

But we don't really know where the O.P. is biasing in preference,
whether there's no memory and no disk, or whether it's just the matter
of "veiling" the presence of the DBMS.
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Dear twosk

>I heard from somone that i could use PostgreSQL, but I cannot find any information
>that confirms or denies it.
>

AFAIK There was a discussion on the same topic in Dec2003 please search
the list and you will geta solution

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Sai Hertz And Control Systems Pvt Ltd,
http://saihertz.rediffblogs.com
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