Dets bug

[Alexey Shchepin]

Hi!

I got the following error today:

=CRASH REPORT==== 18-Oct-2004::13:30:28 ===
  crasher:
    pid: <0.15846.65>
    registered_name: []
    error_info: {aborted,{badarg,[roster,"dtim",3]}}
    initial_call: {gen,init_it,
                      [gen_fsm,
                       <0.218.0>,
                       <0.218.0>,
                       ejabberd_c2s,
                       [{gen_tcp,#Port<0.1903435>},
                        [{access,c2s},
                         {shaper,c2s_shaper},
                         starttls,
                         {certfile,"./ssl.pem"}]],
                       []]}
    ancestors: [ejabberd_c2s_sup,ejabberd_sup,<0.35.0>]
    messages: [{<0.146.0>,
                   {error,{dets_bug,roster,
                                    {lookup_keys,
                                        [{"dtim",{"dottedmag","jabber.ru",[]}}]}
,
                                    {11,'EXIT'}}}}]
    links: [<0.218.0>]
    dictionary: []
    trap_exit: false
    status: running
    heap_size: 2584
    stack_size: 21
    reductions: 14321
  neighbours:

Then I copied roster.DAT from working DB, repaired it and tried to do
dets:lookup on this key, but it returned empty result.  After that I ran the
following command 3 times and got 3 different results:

(ejabberd@REDACTED)1> mnesia:dirty_read(roster, {"dtim",{"dottedmag","jabber.ru",[]}}).
{badarg,[{erlang,binary_to_term,
                 [<<131,104,10,100,0,6,114,111,115,116,101,114,104,2,107,0,6,109,104,97,109,...>>]},
         {dets_v9,per_set_key,3},
         {dets_v9,eval_work_list,2},
         {dets,update_cache,2},
         {dets,stream_end,5},
         {dets,do_apply_op,4},
         {proc_lib,init_p,5}]}
(ejabberd@REDACTED)2> mnesia:dirty_read(roster, {"dtim",{"dottedmag","jabber.ru",[]}}).
{error,{dets_bug,roster,
                 {lookup_keys,[{"dtim",{"dottedmag","jabber.ru",[]}}]},
                 {14,'EXIT'}}}
(ejabberd@REDACTED)3> mnesia:dirty_read(roster, {"dtim",{"dottedmag","jabber.ru",[]}}).
{error,{bad_object,"/opt/jabber/server/ejabberd/src/Mnesia.ejabberd@REDACTED/roster.DAT"}}

After that all requests to roster table return the last error, and after
restarting this error is unreproduceable.

Erlang version is R10B.

Snip from mnesia:info():

roster         : with 412996   records occupying 95840830 bytes on disc