Automatically backing up SQLite database

Question

My app uses a small SQLite database that I'd like to have backed up. I'm assuming this won't happen automatically, without my coding for it using fullBackupContent, shown below. How do I modify the content of my backupscheme.xml to set the include path correctly? I prefer to set the db location at runtime.

My backupscheme.xml looks like

<?xml version="1.0" encoding="utf-8"?>
<full-backup-content >
    <include domain="database" path="device_info.db"/>
</full-backup-content

My manifest contains:

    <application
    android:allowBackup="true"
    android:icon="@drawable/time_machine_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme" 
    android:name="mypackage.myapp"
    android:fullBackupContent="@xml/backupscheme" 
    >

Um, if your database is named device_info.db, it would seem like you have the right stuff for it to get backed up. — CommonsWare
– CommonsWare, Commented Mar 4, 2016 at 16:48
Well, that's not the name, but I thought I had to populate path with the full path, something like /data/mypackage.myapp/databases/mydatabase.db — Phil O
– Phil O, Commented Mar 4, 2016 at 16:54
why do you think that it wont happen automatically? i though that if you define android:allowBackup="true", everything is backed up included databases not? — Emil
– Emil, Commented Mar 22, 2018 at 15:41

CommonsWare · Accepted Answer · 2016-03-04 17:10:51Z

4

<include domain="database" path="device_info.db"/>

Here, the domain indicates the root directory in which the path is interpreted. database maps to where SQLite databases are stored by default, if you use:

getDatabasePath() on Context
SQLiteOpenHelper with just a plain filename
openOrCreateDatabase() with just a plain filename

In that case, the filename should be your path value.

If your database is stored somewhere else for some reason, the <include> directive would need some adjustment.

answered Mar 4, 2016 at 17:10

CommonsWare

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11 Comments

Phil O Over a year ago

That simplifies things. Thank you. Do you know when/how often the auto backup actually occurs? Is there a way to force the issue?

CommonsWare Over a year ago

@PhilO: For testing, follow the instructions. In the "real world", I have no idea when/how often the backup occurs, other than it is tied to the conditions listed in the documentation.

Mark Over a year ago

@CommonsWare well, that's the thing. In my tests, I have found that I'm not missing any data which leads me to speculate that maybe the backup functionality does something like PRAGMA wal_checkpoint(2) stackoverflow.com/questions/12928294/…

Mark Over a year ago

Just to give some more details when backing up the app where the .db, .db-shm and .db-wal files exist (but only the .db specified in backup rules XML): When I use ADB to trigger the backup, then do Clear data, then restore, I notice both the .db and .db-wal files are restored in original form/size (i.e. no checkpoint occurred). The .db-shm is not restored, but I guess that's not needed anyway.

Mark Over a year ago

As a side note, not all wal_checkpoint commands delete the -wal file. For example, PRAGMA wal_checkpoint(TRUNCATE) results in a 0 length -wal file. Regardless, no type of wal_checkpoint occurs during backup/restore.

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