Re: WAL logging problem in 9.4.3?

Hi,

At Sun, 2 Oct 2016 21:43:46 +0900, Michael Paquier <michael(dot)paquier(at)gmail(dot)com> wrote in <CAB7nPqTKOyHkrBSxvvSBZCXvU9F8OT_uumXmST_awKsswQA5Sg(at)mail(dot)gmail(dot)com>
> On Thu, Sep 29, 2016 at 10:02 PM, Kyotaro HORIGUCHI
> <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp> wrote:
> > Hello,
> >
> > At Thu, 29 Sep 2016 16:59:55 +0900, Michael Paquier <michael(dot)paquier(at)gmail(dot)com> wrote in <CAB7nPqT5x05tG7aut1yz+WJN76DqNz1Jzq46fSFtee4YbY0YcA(at)mail(dot)gmail(dot)com>
> >> On Mon, Sep 26, 2016 at 5:03 PM, Kyotaro HORIGUCHI
> >> <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp> wrote:
> >> > Hello, I return to this before my things:)
> >> >
> >> > Though I haven't played with the patch yet..
> >>
> >> Be sure to run the test cases in the patch or base your tests on them then!
> >
> > All items of 006_truncate_opt fail on ed0b228 and they are fixed
> > with the patch.
> >
> >> > Though I don't know how it actually impacts the perfomance, it
> >> > seems to me that we can live with truncated_to and sync_above in
> >> > RelationData and BufferNeedsWAL(rel, buf) instead of
> >> > HeapNeedsWAL(rel, buf). Anyway up to one entry for one relation
> >> > seems to exist at once in the hash.
> >>
> >> TBH, I still think that the design of this patch as proposed is pretty
> >> cool and easy to follow.
> >
> > It is clean from certain viewpoint but additional hash,
> > especially hash-searching on every HeapNeedsWAL seems to me to be
> > unacceptable. Do you see it accetable?
> >
> >
> > The attached patch is quiiiccck-and-dirty-hack of Michael's patch
> > just as a PoC of my proposal quoted above. This also passes the
> > 006 test. The major changes are the following.
> >
> > - Moved sync_above and truncted_to into RelationData.
> >
> > - Cleaning up is done in AtEOXact_cleanup instead of explicit
> > calling to smgrDoPendingSyncs().
> >
> > * BufferNeedsWAL (replace of HeapNeedsWAL) no longer requires
> > hash_search. It just refers to the additional members in the
> > given Relation.
> >
> > X I feel that I have dropped one of the features of the origitnal
> > patch during the hack, but I don't recall it clearly now:(
> >
> > X I haven't consider relfilenode replacement, which didn't matter
> > for the original patch. (but there's few places to consider).
> >
> > What do you think about this?
>
> I have moved this patch to next CF. (I still need to look at your patch.)

Thanks for considering that.

regards,

--
Kyotaro Horiguchi
NTT Open Source Software Center