Horton

Re: WAL logging problem in 9.4.3?

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Fujii Masao <masao.fujii@gmail.com>
Cc: Andres Freund <andres@anarazel.de>, Martijn van Oosterhout <kleptog@svana.org>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2015-07-09T17:27:43Z
Lists: pgsql-hackers 
Fujii Masao <masao.fujii@gmail.com> writes:
> On Tue, Jul 7, 2015 at 12:49 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> One idea I had was to allow the COPY optimization only if the heap file is
>> physically zero-length at the time the COPY starts.

> This seems not helpful for the case where TRUNCATE is executed
> before COPY. No?

Huh?  The heap file would be zero length in that case.

> So, if COPY is executed multiple times at the same transaction,
> only first COPY can be optimized?

This is true, and I don't think we should care, especially not if we're
going to take risks of incorrect behavior in order to optimize that
third-order case.  The fact that we're dealing with this bug at all should
remind us that this stuff is harder than it looks.  I want a simple,
reliable, back-patchable fix, and I do not believe that what you are
suggesting would be any of those.

			regards, tom lane

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