[ZODB-Dev] Re: RelStorage now in Subversion

Tres Seaver tseaver at palladion.com
Thu Jan 31 12:43:24 EST 2008


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Shane Hathaway wrote:
> Hi all,
> 
> RelStorage now exists in the Zope subversion repository here:
> 
>    http://svn.zope.org/relstorage/trunk/
> 
> I have also created a wiki page:
> 
>    http://wiki.zope.org/ZODB/RelStorage
> 
> Testing help and database-specific advice would be appreciated!  With 
> both PostgreSQL and Oracle, all relevant ZODB tests pass and I can 
> create a Plone 3 site, but I haven't tested other Zope applications, 
> more than one machine at a time, or Windows.
> 
> Furthermore, I wonder what suggestions any Oracle gurus might have. 
> According to charts I've made, Oracle appears to be leading already in 
> read performance (faster than PostgreSQL and FileStorage+ZEO), but the 
> write performance is plain dismal.  Is it because I'm using two-phase 
> commit?  I don't know.
> 
> Anyway, have fun with the code!  A release is planned for the end of 
> February.

I've got a question for you on the removal of the LISTEN / NOTIFY stuff
in the Postgresql adapter:  it looks to me as though your code was not
doing the async check-for-notifies as shown in the 'notify.py' in the
psycopg2 examples:

http://www.initd.org/tracker/psycopg/browser/psycopg2/trunk/examples/notify.py

So, any notifies you got were only capture on the basis of "syncrhonous"
activity (a cursor doing some other work).  Could that explain the
unreliability which caused you to remove it?  The symptom would be like
the time that the ZEO async stuff got dropped in Zope3 during the
Twisted integration[1]:  a "busy" client would stay up to date, but an
idle one would serve stale objects from cache.

> BTW, thanks again to Jarn for making this possible.

Yay, Jarn.


[1] http://thread.gmane.org/gmane.comp.web.zope.zope3/15286/focus=15353


Tres.
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===================================================================
Tres Seaver          +1 540-429-0999          tseaver at palladion.com
Palladion Software   "Excellence by Design"    http://palladion.com
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