Reading uncommitted changes (dirty read) from SQLite database

I wrote an application (using Qt in C++) which inserts data into a SQLite database. Another application reads data from the same database, but I noticed that it is not possible to read uncommitted data (dirty read). I would like instead to be able to read data even if it is not committed yet.

Reading 开发者_Go百科the SQLite documentation I found the pragma read_uncommitted which, from what I understand, should be what I need. Problem is that, even if I set that to true, I cannot get uncommitted data.

I tried to run my application which performs the insertion process, and, at the same time, start the sqlite3 client. I set the pragma to true and I try to count the records inside the table. What I get is always 0 (database was empty before my insertion process started), until the entire process finishes where I immediately get the entire data.

Am I doing something wrong? Isn't this pragma supposed to make the sqlite3 client behave differently?

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I answer to myself: no, it seems it is not possible. The read_uncommitted isolation mode requires to enable the shared cache, which is possible currently only for different threads living in the same process. This seems the best place to study this: http://www.sqlite.org/sharedcache.html.

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I enabled READ_UNCOMMITTED:

PRAGMA read_uncommitted=true;

And, set WAL mode which seems recommanded in Use of shared-cache is discouraged as shown below:

Shared-cache mode is an obsolete feature. The use of shared-cache mode is discouraged. Most use cases for shared-cache are better served by WAL mode.

PRAGMA journal_mode=wal;

Then, I tried dirty read with 2 transactions (2 command prompts) but it didn't occur.