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Re: mm_last_pg+1 != filesize

On 22/12/15 08:23, Howard Chu wrote:

Hallvard Breien Furuseth wrote:

Do env_sync() and commit() survive the test program from ITS#7886?
It creates a datafile which ends before mm_last_pg+1.


That would probably crash on Windows, I'll check it later. Annoying that
Windows doesn't just flush whatever exists and move on.

Could add a filesize check to env_open and fail if last_pgno doesn't
match.


Not enough if there are several writer processes.
For a growing file, the check would have to go in mdb_txn_begin().


I'm not too fussed about it, you have to be deliberately
malicious to create this condition. You get a Bus Error or a SEGV -
that's a lot safer than tamely returning an error code that the caller
could ignore.
Not malicious. Omit some commits like slapadd -q does, and it can happen naturally. Maybe slapadd -q can do just that with large IDLs. 

I think MDB_meta and MDB_txn need "last written page" maintained
by mdb_page_flush().  Can VL32 wait for MDB_DATA_VERSION > 1?