Horton

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

Alvaro Herrera <alvherre@alvh.no-ip.org>

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From: Alvaro Herrera <alvherre@alvh.no-ip.org>
To: Peter Geoghegan <pg@bowt.ie>
Cc: pgsql-hackers@postgresql.org, "Wood, Dan" <hexpert@amazon.com>
Date: 2017-09-28T20:07:09Z
Lists: pgsql-hackers 
Peter Geoghegan wrote:
> On Thu, Sep 28, 2017 at 7:47 AM, Alvaro Herrera <alvherre@alvh.no-ip.org> wrote:
> > Fix freezing of a dead HOT-updated tuple
> 
> If I run Dan Wood's test case again, the obvious symptom (spurious
> duplicates) goes away. However, the enhanced amcheck, and thus CREATE
> INDEX/REINDEX, still isn't happy about this:
> 
> postgres=# select bt_index_check('t_pkey', true);
> DEBUG:  00000: verifying presence of required tuples in index "t_pkey"
> LOCATION:  bt_check_every_level, verify_nbtree.c:424
> ERROR:  XX000: failed to find parent tuple for heap-only tuple at
> (0,6) in table "t"
> LOCATION:  IndexBuildHeapRangeScan, index.c:2597
> Time: 3.699 ms

... Rats, I obviously missed the message where you said that amcheck
detected this problem.

Odd that it's not fixed.  I guess there's still some more work to do
here ...

-- 
Álvaro Herrera                https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

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.