Is there a way to open the same db in both readonly mode and write mode

[quangson91]

I have some usecase that need open db in two modes.
For example:

• The trust query -> can be execute in writable connect.
• The un trust query -> My purpose is that user type query for read data. BUT prevent they edit/update anything. So I want to use db readonly in this case.

Eg:

final dbWriable = await openDatabase('data.db');
final dbReadOnly = await openReadOnlyDatabase('data.db');

But it seems the dbReadonly still able to insert/update/delete data.

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So is there a way to do that ?
Or am I missing some config.

Thx!

[alextekartik]

By default, openDatabase and openReadOnlyDatabase uses the flag singleInstance: true which means "The first to open wins" and any other call to openDatabase will get the same instance (i.e. in your case not read-only). One solution is to set this flag to false. This is not something many people used as it means that you might encounter lock issue (which means sometimes retrying an operation) when the 2 instances access the database at the same time.

What you can try (so unfortunately here you cannot use openReadOnlyDatabase as it does not have this options):

// Open in write mode
var dbWritable = await openDatabase(path, readOnly: false, singleInstance: false);
// Open in read mode
var dbReadOnly = await openDatabase(path, readOnly: true, singleInstance: false);

[quangson91]

It worked for me.

May be an extra question.
You said:

This is not something many people used as it means that you might encounter lock issue (which means sometimes retrying an operation) when the 2 instances access the database at the same time.

So, is there a way that check if query is writable query which mean, that query may change the database.

Thank you so much for the fast reply & support! (bow)

[alextekartik]

So, is there a way that check if query is writable query which mean, that query may change the database.

Parsing SQL could be very complex. For simplicity, I would assume that any statement not starting with SELECT could potentially change the database

[quangson91]

Thank you for the suggestion!
I think I will choose solution open db read-only mode and using WAL mode.

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Thank you for build the so good library!