std::string const &table)

{

auto const sql = "SELECT count(*) FROM pg_tables"

" WHERE schemaname='{}' AND tablename='{}'"_format(

schema.empty() ? "public" : schema, table);

auto const res = db_connection.query(PGRES_TUPLES_OK, sql);

char const *const num = res.get_value(0, 0);

return num[0] == '1' && num[1] == '\0';

{

pg_conn_t db_connection{options.database_options.conninfo()};

auto const settings = get_postgresql_settings(db_connection);

try {

log_info("Database version: {}", settings.at("server_version"));

auto const version_str = settings.at("server_version_num");

auto const version = std::strtoul(version_str.c_str(), nullptr, 10);

if (version < get_minimum_postgresql_server_version_num()) {

throw std::runtime_error{

"Your database version is too old (need at least {})."_format(

get_minimum_postgresql_server_version())};

}

auto const postgis_version = get_postgis_version(db_connection);

log_info("PostGIS version: {}.{}", postgis_version.major,

postgis_version.minor);

// If we are in append mode and the middle nodes table isn't there,

// it probably means we used a flat node store when we created this

// database. Check for that and stop if it looks like we are missing

// the node location store option.

if (options.append && options.flat_node_file.empty()) {

if (!has_table(db_connection, options.middle_dbschema,

options.prefix + "_nodes")) {

throw std::runtime_error{

"You seem to not have a nodes table. Did "

"you forget the --flat-nodes option?"};

}

}

} catch (std::out_of_range const &) {

// Thrown by the settings.at() if the named setting isn't found

throw std::runtime_error{"Can't access database setting."};

}