Re: Page Leak?

Andrew Spott wrote:

Can I use `mdb_dump | mdb_load` (roughly) to get the db back to a stable state?  Any ideas what is going on?  I have no idea how to reproduce this bug, so I'm not sure what to put in a bug report... and I can't share the db.

Yes, mdb_dump feeding mdb_load should give you a stable DB.

-Andrew

On Tue, Nov 19, 2019 at 1:23 PM Andrew Spott <andrew.spott@gmail.com mailto:andrew.spott@gmail.com> wrote:

mdb_dump didn't complain.

-Andrew

On Tue, Nov 19, 2019 at 9:49 AM Howard Chu <hyc@symas.com <mailto:hyc@symas.com>> wrote:

    Andrew Spott wrote:
    > When looking at the code for mdb_env_copyfd1 (the copy with compaction function), there is this clause[0]:
    >
    > if (rc == MDB_SUCCESS && root != new_root) {
    >     rc = MDB_INCOMPATIBLE; /* page leak or corrupt DB */
    >  }
    >
    >
    > Since this happens at the end of the function, and I'm seeing the mdb_copy -c takes a while, I figured this was the error that I was seeing.
    >
    > If this isn't it, then what am I looking at?  If it is a corrupt DB, is there anything I can do to figure out how to fix this?

    Try using mdb_dump to get a backup instead, see if it succeeds or complains.
    >
    > [0] https://github.com/LMDB/lmdb/blob/c3e6b4209eed13af4a3670e5f04f42169c08e5c6/libraries/liblmdb/mdb.c#L10311-L10312
    >
    > -Andrew
    >
    > On Sat, Nov 16, 2019 at 7:24 AM Howard Chu <hyc@symas.com <mailto:hyc@symas.com> <mailto:hyc@symas.com <mailto:hyc@symas.com>>> wrote:
    >
    >     Andrew Spott wrote:
    >     > I apologize if this is the wrong place to ask this, let me know if there is someplace better.
    >     >
    >     > So, when doing a `mdb_copy -c`, I've run into the error message:
    >     >
    >     > mdb_copy: copying failed, error -30784 (MDB_INCOMPATIBLE: Operation and DB incompatible, or DB flags changed)
    >     >
    >     > When looking at the mdb_copy man page, it says that mdb_copy with compaction might fail if the database has a 'page leak'.
    >     >
    >     > Since that appears to be what has happened...
    >
    >     The error message you got has nothing to do with a page leak.
    >
    >     > can anyone tell me what that means?  Does this mean that the data could be corrupted?  How do I fix this?
    >     >
    >     > Thanks!
    >     >
    >     > -Andew