[erlang-questions] Mnesia cluster across releases

[Daniel Dormont]

So it turns out my problem may be more specific. What happened now is
that I have a particular table where the only copy of that table was
on a node that was shut down and is now lost. Is there any way to
recover from that? I'm ok with completely deleting the table from the
schema but a simple

mnesia:delete_table(tabname).

results in

{aborted,{no_exists,tabname}}

Anything I can do there, or is my whole schema screwed?

On Wed, Mar 19, 2014 at 1:05 AM, Chandru
<chandrashekhar.mullaparthi@REDACTED> wrote:
> On 18 March 2014 21:38, Daniel Dormont <dan@REDACTED> wrote:
>>
>> Hi all,
>>
>> Can a Mnesia cluster exist across two OTP releases, specifically R15B
>> and R16B? I'm testing some upgrades here and seeing this error about
>> two minutes after trying to join a node running R16B to an existing
>> cluster running R15B:
>
>
> The simplest way to test this is to try this on two standalone nodes, one
> running R15B and the other R16B. I've tried this, and had no problem joining
> an R15B-1 node into an R16B-2 node.
>
> You say "trying to join", how exactly are you doing this? When a node joins
> an existing mnesia installation, it should not have a schema of its own.
>
> Chandru
>
>>
>> =ERROR REPORT==== 2014-03-18 17:13:29 ===
>> Mnesia('ejabberd@REDACTED'): ** ERROR ** (core
>> dumped to file:
>> "/var/lib/ejabberd/MnesiaCore.ejabberd@REDACTED")
>>  ** FATAL ** Schema update error {{badmatch,
>>                                    {error,
>>                                     {bad_object_header,
>>                                      "/var/lib/ejabberd/schema.DAT"}}},
>>                                   [{mnesia_dumper,dets_insert,4,
>>
>> [{file,"mnesia_dumper.erl"},{line,342}]},
>>                                    {mnesia_dumper,insert_cstruct,5,
>>
>> [{file,"mnesia_dumper.erl"},{line,1117}]},
>>                                    {mnesia_dumper,insert_ops,6,
>>
>> [{file,"mnesia_dumper.erl"},{line,309}]},
>>                                    {mnesia_dumper,perform_update,4,
>>
>> [{file,"mnesia_dumper.erl"},{line,292}]},
>>                                    {mnesia_dumper,update,3,
>>
>> [{file,"mnesia_dumper.erl"},{line,273}]},
>>                                    {mnesia_tm,do_commit,3,
>>                                     [{file,"mnesia_tm.erl"},{line,1780}]},
>>                                    {mnesia_tm,commit_participant,6,
>>
>> [{file,"mnesia_tm.erl"},{line,1699}]}]} [{op,
>>
>>        merge_schema,
>>
>>        [{name,
>>
>> ... etc.
>>
>> If not, are there strategies for dealing with such an upgrade? Or is
>> this caused by something else entirely?
>>
>> Thanks,
>> Dan
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>
>