[ZODB-Dev] RelStorage: Pack no longer holding the commit lock for prolonged periods

[Martijn Pieters]

I've cleared the last area where RelStorage packing could hold the
transaction lock for long periods of time, during empty transaction
deletion:

  http://zope3.pov.lt/trac/changeset/121783/relstorage/trunk

During a large pack, this section could potentially hold the
transaction lock for a long period of time and thus block an entire
RelStorage Zope cluster. It now deletes transactions is batches of
1000 and releases the lock in between.

Shane, I have only tested this against PostgreSQL and Oracle, but I am
pretty confident the MySQL SQL syntax is correct. This has been run on
the live Elkjøp Oracle cluster without problems.

-- 
Martijn Pieters