Re: MDB_CORRUPTED: Located page was wrong type

[Howard Chu <hyc@symas.com>]

opensource@gmx-topmail.de wrote:
> Hello,
>
> We build an Android app with LMDB and are now seeing an error report with the
> following info:
> error -30796: MDB_CORRUPTED: Located page was wrong type
>
> We also logged some general info about the DB:
> entries=25381 depth=3 branch-pages=43 leaf-pages=891 overflow-pages=10
> page-size=4096 last-page-number=4464 last-tx-id=3752 size=536870912
> max-readers=126 readers=4
>
> It is an Android 6.0.1 device, and that's about all the info we have.
> Unfortunately we do not have the DB files etc.
>
> The app runs a LMDB version from mdb.master (45a8827 Howard Chu on 9/1/16 at
> 1:41 AM, ITS#8489 reset cursor EOF flag in cursor_set).

Generally you should not use mdb.master in production, as it's a development 
branch.
> DB curruption sounds like a rather bad issue. Any idea how this could have
> happend?

Not offhand. We've seen a few corruptions on Windows due to running without 
fully synchronous transactions, with OS crashes and/or faulty hard drives. 
It's pretty rare for phones to crash though.

> Also, is there any chance to repair this DB (automatically)?

Nothing automated at present. If you had the DB files you could try to scan 
the DB using the previous meta-page to see if it's still intact.

> Thanks for your help,
> Markus


--
  -- Howard Chu
  CTO, Symas Corp.           http://www.symas.com
  Director, Highland Sun     http://highlandsun.com/hyc/
  Chief Architect, OpenLDAP  http://www.openldap.org/project/