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Author Topic: virtual db  (Read 1110 times)

lawman

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virtual db
« on: January 25, 2020, 12:45:41 pm »
is it possible to make a virtual db with sqlite or firebird?

by virtual db I mean, we open multiple db files and work with it as one db, so relationships can be managed between tables across the db files.

thanks

johnmc

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Re: virtual db
« Reply #1 on: January 30, 2020, 12:05:36 pm »
Not with SQLITE it is defined as
Quote
A complete database is stored in a single cross-platform disk file.

see: https://www.sqlite.org/features.html

This can be seen by looking at the TSQL???Connection/TSQLTransaction has only one database name property.
If you were really determined you could have 2 or more database files but the SQLquery would still only point to one or other transaction.

You may need to use mySQL/maria.

John

rvk

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Re: virtual db
« Reply #2 on: January 30, 2020, 12:36:45 pm »
is it possible to make a virtual db with sqlite or firebird?
by virtual db I mean, we open multiple db files and work with it as one db, so relationships can be managed between tables across the db files.
Why would you want to do this?

Most databases will keep all tables in one database-file because it can manage the transactions, integrity, etc.
In Firebird you could use external file but the problem is that an external file could not be available and the whole database integrity would go out of the window if there are relationships to each other.

http://www.firebirdfaq.org/faq16/
https://www.wisdomjobs.com/e-university/firebird-tutorial-210/using-external-files-as-tables-7629.html

Zvoni

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Re: virtual db
« Reply #3 on: January 31, 2020, 08:29:27 am »
In SQLite, why not just attach the "secondary" Database to the primary? Kind of like federated tables in MySQL.
IIRC, SQLite supports this even at runtime
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lawman

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Re: virtual db
« Reply #4 on: January 31, 2020, 06:07:13 pm »
How would you do this?   

Possible with Firebird too?

Wanted to keep tables separate for
1.  User
2.  Common

So I can distribute both to each user.

When updating common tables that user won't change I can just send updated common dB to all.

Zvoni

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Re: virtual db
« Reply #5 on: January 31, 2020, 07:48:12 pm »
How would you do this?   

Possible with Firebird too?

Wanted to keep tables separate for
1.  User
2.  Common

So I can distribute both to each user.

When updating common tables that user won't change I can just send updated common dB to all.
Sounds like replication to me......
One System to rule them all, One IDE to find them,
One Code to bring them all, and to the Framework bind them,
in the Land of Redmond, where the Windows lie
---------------------------------------------------------------------
People call me crazy, because i'm jumping out of perfectly fine aircrafts

 

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