Horton

Re: WAL logging problem in 9.4.3?

Michael Paquier <michael.paquier@gmail.com>

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From: Michael Paquier <michael.paquier@gmail.com>
To: Kyotaro HORIGUCHI <horiguchi.kyotaro@lab.ntt.co.jp>
Cc: david@pgmasters.net, Heikki Linnakangas <hlinnaka@iki.fi>, Alvaro Herrera <alvherre@2ndquadrant.com>, Simon Riggs <simon@2ndquadrant.com>, Tom Lane <tgl@sss.pgh.pa.us>, Andres Freund <andres@anarazel.de>, Masao Fujii <masao.fujii@gmail.com>, kleptog@svana.org, PostgreSQL mailing lists <pgsql-hackers@postgresql.org>
Date: 2016-10-02T12:43:46Z
Lists: pgsql-hackers 
On Thu, Sep 29, 2016 at 10:02 PM, Kyotaro HORIGUCHI
<horiguchi.kyotaro@lab.ntt.co.jp> wrote:
> Hello,
>
> At Thu, 29 Sep 2016 16:59:55 +0900, Michael Paquier <michael.paquier@gmail.com> wrote in <CAB7nPqT5x05tG7aut1yz+WJN76DqNz1Jzq46fSFtee4YbY0YcA@mail.gmail.com>
>> On Mon, Sep 26, 2016 at 5:03 PM, Kyotaro HORIGUCHI
>> <horiguchi.kyotaro@lab.ntt.co.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.)
-- 
Michael

Commits

  1. Add perl2host call missing from a new test file.

  2. Skip WAL for new relfilenodes, under wal_level=minimal.

  3. Revert "Skip WAL for new relfilenodes, under wal_level=minimal."

  4. Back-patch log_newpage_range().

  5. During heap rebuild, lock any TOAST index until end of transaction.

  6. In log_newpage_range(), heed forkNum and page_std arguments.

  7. Back-patch src/test/recovery and PostgresNode from 9.6 to 9.5.

  8. Reduce pg_ctl's reaction time when waiting for postmaster start/stop.

  9. Accelerate end-of-transaction dropping of relations

  10. Redesign the planner's handling of index-descent cost estimation.

  11. Make TRUNCATE do truncate-in-place when processing a relation that was created