This feels to me like a workaround. Tables should be dropped in a correct order. Have you tried to see if we can reorganize tables order in Yaml for doctrine schema instead?

@alongosz I didn't. I replaced the not-working array_reverse trick with another trick.
Studying how the table list is loaded/built from YAML schema is probably also necessary to understand why 3 tables are missing. But my knowledge of Doctrine is limited and I don't manage to explore this schema declaration.

This feels to me like a workaround. Tables should be dropped in a correct order. Have you tried to see if we can reorganize tables order in Yaml for doctrine schema instead?

I didn't. I replaced the not-working array_reverse trick with another trick. Studying how the table list is loaded/built from YAML schema is probably also necessary to understand why 3 tables are missing. But my knowledge of Doctrine is limited and I don't manage to explore this schema declaration.

Ok. Looks like that this could go in. I'm a bit worried about performance of listing foreign keys for every table, but on the other hand it's just for re-installation. Maybe QA can focus on this when testing?

Given the method became more complicated, I'd need to see here 2 things:

1. Unit test coverage for CoreInstaller. I can help with that if it's too complicated.
2. Refactoring. Correct me if I'm wrong, but instead of processing the tables list 2 times, we can in one single loop for each table provide both drop foreign key statements and drop table statement? Or do we really need to drop all foreign keys first and then drop tables?

Something I cooked up on the fly would look like this:

    /**
     * @param \Doctrine\DBAL\Schema\Schema $newSchema
     * @param \Doctrine\DBAL\Platforms\AbstractPlatform $databasePlatform
     *
     * @return string[]
     */
    protected function getDropSqlStatementsForExistingSchema(
        Schema $newSchema,
        AbstractPlatform $databasePlatform
    ): array {
        $schemaManager = $this->db->getSchemaManager();
        if ($schemaManager === null) {
            throw new \LogicException('CoreInstaller: Unable to get Schema manager');
        }

        $existingSchema = $schemaManager->createSchema();
        $statements = [];
        $tables = $newSchema->getTables();
        $supportsForeignKeyConstraints = $databasePlatform->supportsForeignKeyConstraints();

        foreach ($tables as $table) {
            if (!$existingSchema->hasTable($table->getName())) {
                continue;
            }
            if ($supportsForeignKeyConstraints) {
                // cleanup pre-existing database: drop foreign keys
                foreach ($schemaManager->listTableForeignKeys($table->getName()) as $foreignKeyConstraint) {
                    $statements[] = $databasePlatform->getDropForeignKeySQL($foreignKeyConstraint->getName(), $table->getName());
                }
            }

            // cleanup pre-existing database: drop tables
            $statements[] = $databasePlatform->getDropTableSQL($table);
        }

        return $statements;
    }

Haven't tested it however.