``load(oid)`` must die! about zodb

[jamadden]

On RelStorage, lastTransaction() (even with your partial patch) isn't set until some load() operation is requested. That is, RelStorage doesn't read from the DB by itself (e.g., when a storage is created), and only reading from the DB initializes lastTransaction().

Maybe this isn't a problem with the machinery of Connection, maybe it guarantees a call to load() before trying to use lastTransaction(). (Note that sync() alone isn't sufficient.) But it is a problem using the storage directly, one must be aware of the order requirements.

Maybe this is flat out a bug in RelStorage and it should read from the DB if those values are uninitialized.

[jimfulton]

This is moot because with #66, Connection won't be calling lastTransaction on RelStorage instances.

[jamadden]

Good deal!

Does ClientStorage have a valid/correct lastTransaction() immediately after it is created (in the same way FileStorage does)? If so, it still might make sense to change RelStorage to behave like the other storages in this way (that would eliminate the one special-case remaining in zodbconvert).

[jimfulton]

WRT clientStorage and lastTransaction, it's value is "valid" when it's created, but may be z64 until it has connected. (z64 is technically valid, but generally way out of date. :))

[jimfulton]

Long live loadBefore!