---------- Forwarded message ---------- From: Juerg Bircher juerg.bircher@gmail.com Date: Sat, May 28, 2016 at 10:30 PM Subject: Re: (ITS#8430) Improved handling for large number of databases To: Hallvard Breien Furuseth h.b.furuseth@usit.uio.no
On Sat, May 28, 2016 at 3:41 AM, Hallvard Breien Furuseth h.b.furuseth@usit.uio.no wrote:
On 28/05/16 03:28, Hallvard Breien Furuseth wrote:
On 27/05/16 23:39, juerg.bircher@gmail.com wrote:
Maybe I am overseeing something as I do not know all the thoughts between the lines.
With ITS#8431 I can think of one thing: (...blah...)
Actually the main reason I worry about lazy init is simply that we've screwed up DBIs many times, so I prefer to go slowly. That's Howard's call though, not mine.
Maybe a good way in between could be to memcpy txn->mt_env->me_dbflags. However md_flags would need to be moved out of the MDB_dbi struct like mt_dbflags or easier just add another array serving as snapshot. This would not break anything with flag initialization as we get a snapshot of them in the mdb_txn_renew0. memcpy uses SSE instructions for x86_64. We should consider to align on 16 byte boundary for best performance. The dbflags could then still be initialized with MDB_UNSUSED as suggested.