[Zope-DB] Flushing _v_ attributes (was: Re: Cache Controlled SQL methods (CCSQLMethod))
Mon, 20 Jan 2003 20:53:59 +0100
Dieter Maurer wrote at 2003-1-19 01:21 +0100:
> Z SQL Methods maintain their cache in volatile attributes ("_v_" attributes).
> These attributes are flushed (in all caches belonging
> to this version) when the object is written.
> There is a possibility to flush the attributes without writing
> the object. It's a bit tricky, though:
> conn= object._p_jar # the connection, the object belongs to
> db= conn.db() # the associated database
> db.invalidate(object._p_oid) # invalidates the object in all caches
> When you invalidate an object in this way, the object must not be
> modified in the current transaction. Otherwise, a "ConflictError"
> will result.
> Of course, this method gives you not such fine grained
> control you get with Cache Controlled Z SQL Methods.
I should add, that neither CacheControlled Z SQL Methods
nor the technique outlined above will work in a ZEO setup.
I fear that in this case you need to write to the Z SQL Method
to invalidate the cache across ZEO clients.