Re: (ITS#7651) LMDB: Uncontrolled database when opened from multiple processes

[h.b.furuseth@usit.uio.no]

I'd call this two doc bugs:

Something should mention that once a page has been used, the file will
never shrink below that page.  (Can't quite say that the file never
shrinks, since WRITEMAP and Windows will set it to exact re-configurable
mapsize in some cases.  If I remember correctly.)
  
mdb_env_copy() and mdb_env_copyfd() should document that

  @node This call can trigger siginficant file size growth if run in
  parallel with write transactions, because it employs a read-only
  transaction. See long-lived transactions under Caveats.

I wonder that means these functions should have a flag parameter.
For some databases, users might prefer a _write_ transaction while
reading the DB, blocking writes while copying.

-- 
Hallvard