Re: (ITS#7774) LMDB assertion failure during Postfix cache cleanup

[wietse@porcupine.org]

Wietse Venema:
> > You're using an old read-only transaction which cannot coexist with:
> > - mdb_env_set_mapsize() which moves the map which a cursor in
> >   the reader is using.
> > - several write-transactions + MDB_NOLOCK. The flag means the writers do
> >   not know about the reader, so they reuse pages from the snapshot the
> >   reader is using.  The reader can survive while the metapages hold
> >   on to its snapshot, i.e. 1 or 2 write commits (I think).

I am willing to be educated. Where in the LMDB API documentation
would I have learned that I have to consider these details?

	Wietse