bundle/Installer/BaseInstaller.php
protected function importSchemaFile(string $schemaFile, string $controlTableName = null): void
    {
        if ($controlTableName !== null) {
            if ($this->db->getSchemaManager()->tablesExist([$controlTableName])) {
                $this->output->writeln('<comment>Schema already exists in the database, skipping schema import for file <info>' . $schemaFile . '</info></comment>');

                return;
            }
        }

        $this->runQueriesFromFile($schemaFile);
    }
protected function importSchemaFile(string $schemaFile, string $controlTableName = null): void
    {
        if ($controlTableName !== null) {
            if ($this->db->getSchemaManager()->tablesExist([$controlTableName])) {
                $this->output->writeln('<comment>Schema already exists in the database, skipping schema import for file <info>' . $schemaFile . '</info></comment>');

                return;
            }
        }

        $this->runQueriesFromFile($schemaFile);
    }
Handle inserting of schema, schema should ideally be in ISO SQL format.

Schema file is created with: mysqldump ngsite --no-data > schema.sql