SQLite findTables Returns Empty Array on External DB.

Confirm this

$ drush ev "var_dump(db_find_tables('batch%'));"
array(0) {
}
$ drush ev "var_dump(db_find_tables('%'));"
array(0) {
}

Here's a quick fix

I'm getting empty list of tables on default local setup with sqlite

How about adding a $include_main = FALSE parameter to \Drupal\Core\Database\Driver\sqlite\Connection::getAttachedDatabases(), and calling it with TRUE in findTables()? This way anyone who calls getAttachedDatabases() should be aware that it doesn't return the main schema by default :)

Also, it's really strange that \Drupal\KernelTests\Core\Database\SchemaTest::testFindTables() doesn't fail in HEAD..

It does not fail because tests always have $attached_dbs non-empty, running this test I always get kind of that in $attached_dbs:

$attached_dbs array (
  'test93593384' => 'test93593384',
  'test93593384_shared_' => 'test93593384_shared_',
)
$attached_dbs array (
  'test93593384' => 'test93593384',
  'test93593384_shared_' => 'test93593384_shared_',
)
$attached_dbs array (
  'test93593384' => 'test93593384',
)

Right, we can't test this in a kernel or functional test because of how we instantiate the database in the a environment by using prefixes. I guess manual testing will have to do for this issue :)

What do you think about the fist part of #5?

I find in nice workaround for specific driver to manage schemas/attached databases for sqlite (recall few issues with it in pgsql meantime)
Will work on it tonight

Used to add tests but that really not possible, probably it need CR

To test it manually - use quickstart install (sqlite) and

drush ev 'var_dump(\Drupal::database()->schema()->findTables("%"));'

which returns nothing without patch and all tables on patched core

I also tested it manually and it works fine!

+++ b/core/tests/Drupal/KernelTests/Core/Database/SchemaTest.php
@@ -1246,6 +1246,13 @@ public function testFindTables() {
+    // Make sure prefixed table is not visible for default connection.
+    Database::removeConnection('test');
+    $schema = Database::getConnection()->schema();
+    $tables = $schema->findTables('test_%');
+    sort($tables);
+    $this->assertEquals(['test_1_table'], $tables);

So HEAD will pass this test on SQLite?

@alexpott yes, that's just extra case for existing coverage
Basically in tests we always have kinda test93593384 database attached ( as #6 trying to explain

So I've read

    // The SQLite implementation doesn't need to use the same filtering strategy
    // as the parent one because individually prefixed tables live in their own
    // schema (database), which means that neither the main database nor any
    // attached one will contain a prefixed table name, so we just need to loop
    // over all known schemas and filter by the user-supplied table expression.

carefully many times. And I'm not sure the solution here is correct. I think we should do something like

$attached_dbs = $this->connection->getAttachedDatabases();
// If there are no attached databases use the main database.
if (empty($attached_dbs)) {
  $attached_dbs['main'] = 'main';
}

The reason I don't think the solution is correct is because if you did - var_dump(\Drupal\Core\Database\Database::getConnection('my_prefix')->schema()->findTables("%")); this would include main and that's not right either.

To test the patch from comment #9 with only the added test.

Test patch does not catch the issue, any idea how to cover it?

I would like to postpone this issue on #3106531: Notify in Status Report that per-table database prefixes are no longer supported, and will throw errors in Drupal 10.0. The two issue might seem not to be related, only they both use the class variable $this->prefixes. And the other issue needs to be fixed before the release of 9.0.

test-only reroll for 9.0.x

Added related D7 issue to summary as well #1713332: The SQLite database driver fails to drop simpletest tables

Added related for blocker #3106531: Notify in Status Report that per-table database prefixes are no longer supported, and will throw errors in Drupal 10.0

As blocker targeted to 9.3 here could be workaround

Fix for fail-test (sqlite only) and patch with early fix

D7 issue was commited with extra tests that could be forward-ported from #1713332: The SQLite database driver fails to drop simpletest tables