presto-main/src/main/java/io/prestosql/connector/system/SystemTablesMetadata.java/SystemTablesMetadata/listTableColumns
class SystemTablesMetadata:    @Override
    public Map<SchemaTableName, List<ColumnMetadata>> listTableColumns(ConnectorSession session, SchemaTablePrefix prefix)
    {
        requireNonNull(prefix, "prefix is null");

        if (prefix.getTable().isPresent()) {
            // if table is concrete we just use tables.getSystemTable to support tables which are not listable
            SchemaTableName tableName = prefix.toSchemaTableName();
            return tables.getSystemTable(session, tableName)
                    .map(systemTable -> singletonMap(tableName, systemTable.getTableMetadata().getColumns()))
                    .orElseGet(ImmutableMap::of);
        }

        ImmutableMap.Builder<SchemaTableName, List<ColumnMetadata>> builder = ImmutableMap.builder();
        for (SystemTable table : tables.listSystemTables(session)) {
            ConnectorTableMetadata tableMetadata = table.getTableMetadata();
            if (prefix.matches(tableMetadata.getTable())) {
                builder.put(tableMetadata.getTable(), tableMetadata.getColumns());
            }
        }
        return builder.build();
    }