Thanks for opening this thread here. I'm not actually doing anything like this, but it's great to see you pushing the envelop. I have done a lot of work on replicated data, over the years, that's where the following comment comes from.

On 22 May 2008, at 10:36, Stefan H. Holek wrote:

We have put up two boxes in a MySQL master-master replication setup [1]. As long as we only write to one of the masters all is fine. Writing to both masters (and expecting MySQL to sort it out) is giving us trouble. We see things like:

Last_Errno: 1062
Last_Error: Error 'Duplicate entry '41860' for key 1' on query.
Default database: 'prod_zodb'.
Query: 'INSERT INTO new_oid VALUES ()'
I have not read the reference, but it seems that this scheme can never work without keys (OIDs) being qualified by which master they originated on. Otherwise one of the mySQLs would need to be responsible for handing out unique oids. You need an OID origination namespace for each master.

On the other issue, no idea.




Last_Errno: 1050
Last_Error: Error 'Table 'temp_store' already exists' on query.
Default database: 'prod_zodb'.
       zoid        BIGINT NOT NULL PRIMARY KEY,
       prev_tid    BIGINT NOT NULL,
       md5         CHAR(32),
       state       LONGBLOB
      ) ENGINE MyISAM'



On 20.05.2008, at 18:36, Shane Hathaway wrote:

That is mostly correct. You need to replicate transaction, object_state, current_object, and do something with new_oid. There is no requirement to replicate the other tables, since they are used only for packing, although replicating object_ref and object_refs_added may save some work.

The new_oid table is special to the MySQL adapter. RelStorage uses the new_oid table as a kind of sequence. Like any sequence, it is intentionally non-transactional. Perhaps there would be no ill effects in switching it to the InnoDB engine.

Which MySQL replication method are you looking into?

Stefan H. Holek

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