> I assume you've read <https://www.sqlite.org/howtocorrupt.html> .
Thanks. Yes, I had read it but it was worth a refresh.
The very last item gave pause...race condition on Windows. See below.
> It's worth stating that a zero-length database causes no problem for
SQLite.
> It does not trigger any error message if you open that database again and
> start putting legit things in it. It isn't mentioned in the documentation
> (as far as I can see) and it's an edge-case for what constitutes a
legitimate
> SQLite database file, but it does work the way you'd want it to work.
Yes, I knew about that. Not the problem here.
>
> You can intentionally create a zero-length sqlite database by completing
no
> commands which create schema. For example, using the shell tool to create
a
> new database file and then ...
>
> SQLite version 3.8.10.2 2015-05-20 18:17:19 Enter ".help" for usage hints.
> sqlite> BEGIN;
> sqlite> CREATE TABLE myTable (myCol TEXT PRIMARY KEY); INSERT INTO
> sqlite> myTable VALUES ('zxc'); INSERT INTO myTable VALUES ('zxc');
> Error: UNIQUE constraint failed: myTable.myCol
> sqlite> ROLLBACK;
> sqlite> COMMIT;
> Error: cannot commit - no transaction is active
> sqlite> .quit
>
> The above technically fits the description you gave in your original post.
In my case there were about 4 tables created and about 50 INSERTs into them,
and the final COMMIT did not trigger an error. I don't think this is it.
There is an interesting race condition in Windows that is not much talked
about: in the shell. This particular program is run as part of a series of
test cases, and the setup for the test involves deleting the database file
and then running the program in a batch file. Since about Windows 7 the
shell does not wait for a file to be deleted before launching the next
process, and if that process uses a file that is being deleted there is a
race condition to see what happens next. Specifically it seems to be
possible to open a "shadow copy" of the file which can persist while the
original file is deleted. I don't understand exactly what happens, but I
suspect this might be my problem.
I've also put some effort into a clean shutdown, but I don't think that was
the problem. It's stopped happening for now, but not really because I found
and fixed a bug!
Regards
David M Bennett FACS
Andl - A New Database Language - andl.org
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