[ZODB-Dev] RelStorage: Clearing temp_store in replication-friendly way

[Wichert Akkerman]

Stephan Richter wrote:
> On Thursday 24 July 2008, Shane Hathaway wrote:
>    
>>> P.S.: I am quite excited about the memcached support. Does it "just  
>>> work"? I.e. can I run my ZODB in RAM now? ;-)
>>>        
>> I expect the new memcache support to be safe for everyone to use, but we
>> still require the main database to be connected at all times, since
>> memcache provides no ACID properties by itself.  We unfortunately can't
>> do obvious things like cache the current transaction ID for an object,
>> since that would break MVCC.  What we do cache is:
>>
>> 1. The current tid, given an oid and the transaction ID that is active
>> for the current connection.
>>
>> 2. The pickle given an oid and tid.
>>
>> These should both help read-heavy databases, but might be detrimental
>> for write-heavy databases.  My performance test suite, which writes a
>> lot, produced slightly *worse* results with memcache enabled.
>>      
>
> We should get Brian Aker into this discussion, since is one of the main
> architects of MySQL and one of the founders of memcached.
>
> As Shane knows, I have some access to Brian these days, so we could have an
> online meeting talking about it.
>    

Well, if I can make a suggestion :)

 From what I understand a new memcache client library was written for 
MySQL (libmemcache is quite horrible). Python bindings for that library 
would improve many things, including this :)

Wichert.

-- 
Wichert Akkerman<wichert at wiggy.net>    It is simple to make things.
http://www.wiggy.net/                  It is hard to make things simple.

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