postgresql/src
Alvaro Herrera d2599ecfcc Don't mark pages all-visible spuriously
Dan Wood diagnosed a long-standing problem that pages containing tuples
that are locked by multixacts containing live lockers may spuriously end
up as candidates for getting their all-visible flag set.  This has the
long-term effect that multixacts remain unfrozen; this may previously
pass undetected, but since commit XYZ it would be reported as
  "ERROR: found multixact 134100944 from before relminmxid 192042633"
because when a later vacuum tries to freeze the page it detects that a
multixact that should have gotten frozen, wasn't.

Dan proposed a (correct) patch that simply sets a variable to its
correct value, after a bogus initialization.  But, per discussion, it
seems better coding to avoid the bogus initializations altogether, since
they could give rise to more bugs later.  Therefore this fix rewrites
the logic a little bit to avoid depending on the bogus initializations.

This bug was part of a family introduced in 9.6 by commit a892234f830e;
later, commit 38e9f90a22 fixed most of them, but this one was
unnoticed.

Authors: Dan Wood, Pavan Deolasee, Álvaro Herrera
Reviewed-by: Masahiko Sawada, Pavan Deolasee, Álvaro Herrera
Discussion: https://postgr.es/m/84EBAC55-F06D-4FBE-A3F3-8BDA093CE3E3@amazon.com
2018-05-04 18:24:45 -03:00
..
backend Don't mark pages all-visible spuriously 2018-05-04 18:24:45 -03:00
bin Allow MSYS as well as MINGW in Msys uname 2018-05-04 14:59:36 -04:00
common
fe_utils
include Re-think predicate locking on GIN indexes. 2018-05-04 11:27:50 +03:00
interfaces Further -Wimplicit-fallthrough cleanup. 2018-05-01 19:53:48 -07:00
makefiles Remove Windows module-list-dumping code. 2018-04-30 13:20:13 -04:00
pl Update expected files for older Python versions 2018-05-03 20:29:54 -04:00
port Further improve code for probing the availability of ARM CRC instructions. 2018-05-03 11:32:57 -04:00
template
test Re-think predicate locking on GIN indexes. 2018-05-04 11:27:50 +03:00
timezone Sync our copy of the timezone library with IANA release tzcode2018e. 2018-05-04 12:26:25 -04:00
tools Provide for testing on python3 modules when under MSVC 2018-05-04 15:22:48 -04:00
tutorial
.gitignore
DEVELOPERS
Makefile
Makefile.global.in Un-break contrib install with llvm. 2018-04-28 14:45:39 -04:00
Makefile.shlib
nls-global.mk