Create SQLite inmemory database from bytearray

Question

I need to process data from a SQLite database using some Java code. The problem is that the database is retrieved from an external service and thus it is only available as an InputStream.

I would really like to avoid saving the db to the file system before starting to process the data, but I don't see a way of doing it.

I am currently using SqlJet, as it provides an option to create an in-memory database. However there seems to be no way to turn an InputStream / byte array into a database.

There's nothing forcing me to use SqlJet, it can be easily replaced by any other tool if it provides the needed functionality.

I don't think the SQLite API supports opening a memory block of some sorts -> sqlite.org/c3ref/open.html - maybe if you create some in memory filesystem but I'd suggest you just save the stream to a file and use that instead. — zapl
– zapl, Commented Aug 24, 2012 at 14:40
Apparently you can do this by writing a VFS module for SQLite. See the pointers to some docuemtation at sqlite-users.sqlite.narkive.com/lvdwVRm4/… though I don’t know how much code it would take. — andrewdotn
– andrewdotn, Commented Nov 25, 2022 at 18:58

user610650 · Accepted Answer · 2012-08-24 17:09:57Z

1

It can't be done as such. Perhaps Java supports some mechanism to create some form of virtual file that is presented locally (to the current process) as some physical file.

I can think of one way to work-around the limitation, but that may not be doable or acceptable within your context. You can change the service to return a dump of the database and load that in the receiver's in-memory database:

Here is a way to generate the dump:

# sqlite3
SQLite version 3.7.11 2012-03-20 11:35:50
Enter ".help" for instructions
Enter SQL statements terminated with a ";"
sqlite> create table foo (i text);
sqlite> insert into foo values ('a');
sqlite> insert into foo values ('b');
sqlite> .dump
PRAGMA foreign_keys=OFF;
BEGIN TRANSACTION;
CREATE TABLE foo (i text);
INSERT INTO foo VALUES('a');
INSERT INTO foo VALUES('b');
COMMIT;

answered Aug 24, 2012 at 17:09

user610650

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1 Comment

Andrew Over a year ago

Great idea, it answers the question. Thanks!

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