Re: how to create multiple databases running in different dirs - Mailing list pgsql-general

From John W Higgins
Subject Re: how to create multiple databases running in different dirs
Date
Msg-id CAPhAwGxM+4a56vM9-rPie4bw+tgxnE=x14q80yeCi_qy4bntqw@mail.gmail.com
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In response to Re: how to create multiple databases running in different dirs  ("frank ernest" <doark@mail.com>)
List pgsql-general
Afternoon Frank,

I believe what you might wish to look at is a single database with a set of schemas[1] which would separate your data in a logical way. You could have a single connection url and then each individual connection could create a schema (or reuse if you wish), set the search path (first example here [2]) and populate the schema (if needed) within your single database 

That would give you your desired isolation but within a simple framework that is PostgreSQL friendly.

John



On Wed, Jul 2, 2014 at 4:24 PM, frank ernest <doark@mail.com> wrote:
> how would an instance of your program know what to connect to, or which
> previous instance its 'predecessor' was ?
> normally, you have ONE database for a given set of applications, and all
> the applications share the same database tables and such.

That's the problem, is there some way to tell pgsql "Go to dir X, open your data base Y and prepare for connections at adress Z and port P"? And could pgsql accept multiple connections on the same address and port? I was thinking of using my pID but that would change and if I used a user created string then if I started only on a single instace of pgsql and pointed it to it's databases the user might get the strings duplicated and that would be no good. I also thought of naming each database with a name generated by using the uuid library but I'm not sure which would be best.
 
If I choose to have multiple servers running on the same machine how would my program start them?
 
> Is each runtime instance of your application to have a new, empty
> database? No data from any other run of the application?
 
No, the dynamically generated content is to be dropped (drop table dynamic_content;) but the rest is to be preserved. The idea is to create a database of a file system but the files contain no data, I only want their metadata and I will add a few additional metadta values to each file.
 
Thanks, David
 

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