How does it work?

Your application will use a modified version of the SQLite library containing the liteReplica code to access your database.

The modifications on the SQLite library are internal and the interface is the same.

On the replica side, you can use another application to access the slave database, using the same liteReplica library used in the master.

The liteReplica libraries will communicate to each other, exchanging transaction data.

So when your application writes to the master database, the liteReplica code will send the transaction to the slave replica and these changes will be applied as a transaction on the slave database.

If your application rolls back the transaction, the same will occur in the slave side.

The slave database is read-only for the application accessing it. Only the lireReplica will update it.

Do I need to change my app code?

No. The litereplica uses the native SQLite3 interface.

In the master side you just need to change the URI string in the database opening from this:


to this:


And then compile and link your application with the litereplica code or library (for C and C++).

For other languages you must have the proper wrapper installed.

What more is needed in the Master side?

Nothing! It’s done.

What about the Slave side?

Assuming that you will use a separate application to keep the slave database, a basic standalone application used solely for the purpose of keeping a db replica would look like this:

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Where the slave database can be?

The slave db can be kept:

1. On a separate device:

2. On the same device, in another app:

3. On the same device, in the same app, using another db connection:

4. On the same device, in the same app, on the same db connection, using an attached database:

Note: If the slave db connection is in another application then this application must be kept open for the database to be updated.


So in the master side as in the slave side you have 2 options:

bind to an address
connect to the peer address

So you can choose which side will connect to the other. This is useful when one side is behind a router or firewall.

Communication Protocols

The litereplica library can use the following protocols:

tcp - in any situation
ipc - master and slave in the same device
inproc - master and slave on the same process

When using both db files on the same device, the protocol does not need to be specified on the URI string. Example:

Master database:


Slave database:




1 master connected to 1 slave

Many replicas

1 master connected to many slaves


1 master connected to 1 slave, and this one to another slave

Usage examples

Basic replica

This is used simply to keep a backup of the database

Readable replica

This is useful when another app needs to access the data in another device even when the main device is off-line

On-line replica

Kind of a readable replica, this is used when your system has an on-line webapp or a site that access your application data and this application needs to use a local database so that it is always accessible.

In this way when there is no access to the internet the main application can still write to its local database and the web-clients can access the on-line replica. When the internet connection is restablished the on-line replica is updated with the master database.

Shared Replica

This is used with applications that we cannot modify, those which we don't have access to its source code. As long as the application does not write to this database file we can use another application accessing the same db file to keep it up-to-date with a master one


-Savepoints are not supported, only normal transactions
-WAL mode is not supported