[Checkins] [zopefoundation/ZODB] 61d2c7: Better historical connection implementation

[GitHub]

  Branch: refs/heads/MVCCAdapter
  Home:   https://github.com/zopefoundation/ZODB
  Commit: 61d2c751620f8f0bb3345e47d8effc2af67ce213
      https://github.com/zopefoundation/ZODB/commit/61d2c751620f8f0bb3345e47d8effc2af67ce213
  Author: Jim Fulton <jim at zope.com>
  Date:   2016-06-15 (Wed, 15 Jun 2016)

  Changed paths:
    M src/ZODB/Connection.py
    M src/ZODB/mvccadapter.py

  Log Message:
  -----------
  Better historical connection implementation

- Lower-weight instances when not using RelStorage

- Still works with new RelStorage instances.

- Doesn't make me include loadBefore in MVCCAdapterInstance objects. :)