[erlang-questions] How to interpret this error message?

[Anthony Kong]

Hi, all,
 
I read from the mailing list a few days ago about using
mnesia:dirty_update_counter() to generate key. I want to use this
feature as well, so I have come up with this little test script:
 
 
====
 
-module(db_seq).
 
-record(counter, {tab, key, value}).
 
-export([init_mnesia_db/0, get_next_seq/1, test/0, setup/0]).
 
-define(SERVER, ?MODULE).
 
get_next_seq(Key) ->
  mnesia:dirty_update_counter(counter, Key, 1).
 
setup() ->
    mnesia:create_schema([node()]),
    mnesia:start(),
    mnesia:create_table(counter, [{disc_copies, [node()]},
                                  {type, ordered_set},
                                  {attributes, record_info(fields,
counter)}]),
    mnesia:stop().
    
 
test() ->
    mnesia:start(),
    mnesia:wait_for_tables([counter], 20000),
    mnesia:dirty_update_counter(counter, a, 1).
 
====
 
I fired up erl with this command line "erl -mnesia dir local". Then I
executed db_seq:setup() in order to create the schema and table.
 
Then I run db_seq:test() in order to obtain an integer value, which
failed with this message:
 
6> db_seq:test().
** exited: {aborted,{combine_error,counter,update_counter}} **
So, what is a "combine_error"? What is the best way to find out the
meaning of these error messages (apart from asking the question in
mailing list)? Is reading the source code the only way? (Don't get me
wrong, I do not mind reading them, but really would like to learn how
you guys decipher this kind of error message normally during
development...)
 
 
Cheers, Anthony
 
 
 
 
 
 
 
 
 
 
 

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