psql.registerCommand ( {
  name = "my.dt",
  help_syntax = "\\my.dt[+] [PATTERN] [-OPTION]",
  help_desc = "list tables possibly sorted by size",

  handler = function(ss, ab, cmd, verbose)
    local filter = "  AND n.nspname <> 'pg_catalog'\n" ..
        "  AND n.nspname !~ '^pg_toast'\n" ..
        "  AND n.nspname <> 'information_schema'\n" ..
        "  AND pg_catalog.pg_table_is_visible(c.oid)\n"

    local sort = "ORDER BY 1, 2";

    local opt = psql.scanSlashOption(ss, psql.OT_NORMAL, false)

    if opt == "-help" then
      print "my.dt[+] [PATTERN] [-OPTION]     list tables, possibly sorted"
      print ""
      print "Options:"
      print "  -asc-size         sorted by size in ascending order"
      print "  -desc-size        sorted by size in descending order"
      return psql.PSQL_CMD_SKIP_LINE;
    end

    if opt and string.sub(opt,1,1)  ~= "-" then
      local schema, tablename, dot
      if opt == "*" then
        filter = "  AND pg_catalog.pg_table_is_visible(c.oid)\n";
      else
        dot = string.find(opt, "%.")
        if dot then
          schema = string.sub(opt, 1, dot - 1)
          tablename = string.sub(opt, dot + 1)
        else
          tablename = opt;
        end
        if schema then
          if schema ~= "*" then
            filter = "  AND n.nspname = '" .. psql.connect():escape(schema) .. "'\n"
          else
            filter = ""
          end
        else
          filter = "  AND pg_catalog.pg_table_is_visible(c.oid)\n"
        end

        if tablename then
          if tablename ~= "*" then
            filter = filter .. "  AND c.relname = '" .. psql.connect():escape(tablename) .. "'\n"
          end
        end
      end
      opt = psql.scanSlashOption(ss, psql.OT_NORMAL, false);
    end

    if opt == "-asc-size" then
      sort = "ORDER BY pg_catalog.pg_table_size(c.oid) ASC"
    elseif opt == "-desc-size" then
      sort = "ORDER BY pg_catalog.pg_table_size(c.oid) DESC"
    end

    local query = [[
SELECT n.nspname AS "Schema",
       c.relname AS "Name",
       CASE c.relkind WHEN 'r' THEN 'table' WHEN 'v' THEN 'view' WHEN 'm' THEN 'materialized view' WHEN 't' THEN 'TOAST' END AS "Type",
       pg_catalog.pg_get_userbyid(c.relowner) AS "Owner" ]]

    if verbose then
      query = query .. ",\n" ..
        [[
       pg_size_pretty(pg_catalog.pg_table_size(c.oid)) AS "Size",
       pg_catalog.obj_description(c.oid, 'pg_class') AS "Description" ]]
    end

    query = query .. "\n" .. [[
FROM pg_catalog.pg_class c
     LEFT JOIN pg_catalog.pg_namespace n ON n.oid = c.relnamespace
WHERE c.relkind IN ('r','v','m')]] .. "\n"

    query = query .. filter
    query = query .. sort

    psql.printQuery(psql.exec(query))

    return psql.PSQL_CMD_SKIP_LINE;
  end } )