CODEWITHSUNDEEP
sqlite
user2123677
user2123677

Reputation: 53

How to attach :memory: databases that have already been created?

I'm only using in memory databases. Now I am creating a file, and want to copy one of the many tables into this file once the database is attached. However, I can't seem to determine how to attach an already instantiated in-memory database.

Passing ':memory:' to the attach statement creates a new database, as it would have no idea which in-memory database to attach to if more than one open. Is there a way to attach by, say, the C pointer of the database to be attached?

This would also be useful if I already have two disk databases open and do not want to call open a third time implicitly by the attach command. If not possible, are there other ways, preferably without creating temporary files?

Upvotes: 1

Views: 1755

Answers (1)

CL.
CL.

Reputation: 180172

Just attach the file DB to the in-memory DB.

If you really want to do this the other way around, you must enable URI file names and use them; the documentation says:

If the unadorned ":memory:" name is used to specify the in-memory database, then that database always has a private cache and is this only visible to the database connection that originally opened it. However, the same in-memory database can be opened by two or more database connections as follows:

ATTACH DATABASE 'file::memory:?cache=shared' AS aux1;

This allows separate database connections to share the same in-memory database. Of course, all database connections sharing the in-memory database need to be in the same process.

Upvotes: 3

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