Horton

Re: [HACKERS] [COMMITTERS] pgsql: Fix freezing of a dead HOT-updated tuple

Peter Geoghegan <pg@bowt.ie>

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From: Peter Geoghegan <pg@bowt.ie>
To: Andres Freund <andres@anarazel.de>
Cc: Alvaro Herrera <alvherre@alvh.no-ip.org>, "Wood, Dan" <hexpert@amazon.com>, pgsql-committers@postgresql.org, "Wong, Yi Wen" <yiwong@amazon.com>, Michael Paquier <michael.paquier@gmail.com>, Robert Haas <robertmhaas@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Date: 2017-12-15T19:03:37Z
Lists: pgsql-hackers 
On Fri, Dec 15, 2017 at 10:58 AM, Andres Freund <andres@anarazel.de> wrote:
>> I have one minor piece of feedback on the upgrading of assertions to
>> ereport()s with ERRCODE_DATA_CORRUPTION: It would be nice if you could
>> upgrade the raw elog() "can't happen" error within
>> IndexBuildHeapRangeScan() to be an ereport() with
>> ERRCODE_DATA_CORRUPTION. I'm referring to the "failed to find parent
>> tuple for heap-only tuple" error, which I think merits being a real
>> user-visible error, just like the relfrozenxid/relminmxid tests are
>> now. As you know, the enhanced amcheck will sometimes detect
>> corruption due to this bug by hitting that error.
>
> I'm not opposed to that, it just seems independent from this thread. Not
> sure I really want to go around and backpatch such a change, that code
> has changed a bit between branches. Happy to do so on master.

The elog(), which was itself upgraded from a simple Assert by commit
d70cf811, appears in exactly the same form in 9.3+. Things did change
there, but they were kept in sync.

-- 
Peter Geoghegan

Commits

  1. Backport addition of rs_old_rel to rewriteheap's state.

  2. Perform a lot more sanity checks when freezing tuples.

  3. Revert bogus fixes of HOT-freezing bug

  4. Fix traversal of half-frozen update chains

  5. Fix freezing of a dead HOT-updated tuple

  6. During index build, check and elog (not just Assert) for broken HOT chain.

  7. Fix WAL replay of locking an updated tuple

  8. Change the way we mark tuples as frozen.