Re: BUG #17245: Index corruption involving deduplicated entries

On 30.10.2021 0:59, Andres Freund wrote:
> On 2021-10-29 14:30:48 -0700, Andres Freund wrote:
>> I think it's moot for now, because of the discovery that waldump for PRUNE
>> doesn't show records marked unused. I'll try to write a patch to change that.
> 
> Attached the quick version. 

Here are WAL archive entries related to page 540 of mediawiki.page, with 
the patch applied:

# grep "rel 1663/19243/19560 blk 540" ~/waldump-everything.txt
rmgr: Heap        len (rec/tot):     59/  7939, tx:    2013796, lsn: 
2/8DA7C498, prev 2/8DA7C470, desc: LOCK off 5: xid 2013796: flags 0x00 
LOCK_ONLY EXCL_LOCK KEYS_UPDATED , blkref #0: rel 1663/19243/19560 blk 
540 FPW
rmgr: Heap        len (rec/tot):     98/    98, tx:    2013796, lsn: 
2/8DAAA0A0, prev 2/8DAA8548, desc: UPDATE off 5 xmax 2013796 flags 0x61 
KEYS_UPDATED ; new off 22 xmax 2013796, blkref #0: rel 1663/19243/19560 
blk 540
rmgr: Heap2       len (rec/tot):     56/    56, tx:          0, lsn: 
2/8DABF558, prev 2/8DABF528, desc: PRUNE latestRemovedXid 2013796 
nredirected 0 ndead 1 nunused 0, dead: [5], blkref #0: rel 
1663/19243/19560 blk 540
rmgr: Heap        len (rec/tot):     54/    54, tx:    2013798, lsn: 
2/8DABF590, prev 2/8DABF558, desc: LOCK off 22: xid 2013798: flags 0x00 
LOCK_ONLY EXCL_LOCK , blkref #0: rel 1663/19243/19560 blk 540
rmgr: Heap        len (rec/tot):     83/    83, tx:    2013798, lsn: 
2/8DABF5C8, prev 2/8DABF590, desc: HOT_UPDATE off 22 xmax 2013798 flags 
0x60 ; new off 41 xmax 2013798, blkref #0: rel 1663/19243/19560 blk 540
rmgr: Heap2       len (rec/tot):     58/    58, tx:          0, lsn: 
2/8DACCBB0, prev 2/8DACCB88, desc: PRUNE latestRemovedXid 2013798 
nredirected 1 ndead 0 nunused 0, redirected: [22->41], blkref #0: rel 
1663/19243/19560 blk 540
rmgr: Heap        len (rec/tot):     59/  7939, tx:    2014289, lsn: 
2/8DE8A460, prev 2/8DE8A438, desc: LOCK off 41: xid 2014289: flags 0x00 
LOCK_ONLY EXCL_LOCK KEYS_UPDATED , blkref #0: rel 1663/19243/19560 blk 
540 FPW
rmgr: Heap        len (rec/tot):     99/    99, tx:    2014289, lsn: 
2/8DEB5250, prev 2/8DEB36D8, desc: UPDATE off 41 xmax 2014289 flags 0x60 
KEYS_UPDATED ; new off 53 xmax 2014289, blkref #0: rel 1663/19243/19560 
blk 540
rmgr: Heap2       len (rec/tot):     58/    58, tx:          0, lsn: 
2/8DEC0420, prev 2/8DEC03F0, desc: PRUNE latestRemovedXid 2014289 
nredirected 0 ndead 1 nunused 1, unused: [41], dead: [22], blkref #0: 
rel 1663/19243/19560 blk 540
rmgr: Heap        len (rec/tot):     54/    54, tx:    2014291, lsn: 
2/8DEC0460, prev 2/8DEC0420, desc: LOCK off 53: xid 2014291: flags 0x00 
LOCK_ONLY EXCL_LOCK , blkref #0: rel 1663/19243/19560 blk 540
rmgr: Heap        len (rec/tot):     82/    82, tx:    2014291, lsn: 
2/8DEC0498, prev 2/8DEC0460, desc: HOT_UPDATE off 53 xmax 2014291 flags 
0x60 ; new off 41 xmax 2014291, blkref #0: rel 1663/19243/19560 blk 540
rmgr: Heap2       len (rec/tot):     58/    58, tx:          0, lsn: 
2/8DED6A10, prev 2/8DED69E8, desc: PRUNE latestRemovedXid 2014291 
nredirected 1 ndead 0 nunused 0, redirected: [53->41], blkref #0: rel 
1663/19243/19560 blk 540
rmgr: Heap        len (rec/tot):     59/  7939, tx:    2014784, lsn: 
2/8DFB15D0, prev 2/8DFB1598, desc: LOCK off 41: xid 2014784: flags 0x00 
LOCK_ONLY EXCL_LOCK KEYS_UPDATED , blkref #0: rel 1663/19243/19560 blk 
540 FPW
rmgr: Heap        len (rec/tot):    100/   100, tx:    2014784, lsn: 
2/8DFDAD20, prev 2/8DFD9180, desc: UPDATE off 41 xmax 2014784 flags 0x60 
KEYS_UPDATED ; new off 57 xmax 2014784, blkref #0: rel 1663/19243/19560 
blk 540
rmgr: Heap2       len (rec/tot):     58/    58, tx:          0, lsn: 
2/8DFE5F90, prev 2/8DFE5F60, desc: PRUNE latestRemovedXid 2014784 
nredirected 0 ndead 1 nunused 1, unused: [41], dead: [53], blkref #0: 
rel 1663/19243/19560 blk 540
rmgr: Heap        len (rec/tot):     54/    54, tx:    2014786, lsn: 
2/8DFE5FD0, prev 2/8DFE5F90, desc: LOCK off 57: xid 2014786: flags 0x00 
LOCK_ONLY EXCL_LOCK , blkref #0: rel 1663/19243/19560 blk 540
rmgr: Heap        len (rec/tot):     82/    82, tx:    2014786, lsn: 
2/8DFE6020, prev 2/8DFE5FD0, desc: HOT_UPDATE off 57 xmax 2014786 flags 
0x60 ; new off 41 xmax 2014786, blkref #0: rel 1663/19243/19560 blk 540
rmgr: Heap2       len (rec/tot):     58/    58, tx:          0, lsn: 
2/8DFFA420, prev 2/8DFFA3F8, desc: PRUNE latestRemovedXid 2014786 
nredirected 1 ndead 0 nunused 0, redirected: [57->41], blkref #0: rel 
1663/19243/19560 blk 540
rmgr: Heap2       len (rec/tot):     53/  7937, tx:          0, lsn: 
2/90CEF528, prev 2/90CEF4E8, desc: VACUUM nunused 3, blkref #0: rel 
1663/19243/19560 blk 540 FPW
rmgr: Heap2       len (rec/tot):     59/    59, tx:          0, lsn: 
2/90CF1448, prev 2/90CEF528, desc: VISIBLE cutoff xid 2014786 flags 
0x01, blkref #0: rel 1663/19243/19560 fork vm blk 0, blkref #1: rel 
1663/19243/19560 blk 540
rmgr: Heap        len (rec/tot):     59/  7943, tx:    2045060, lsn: 
2/93FF90E8, prev 2/93FF90B0, desc: LOCK off 41: xid 2045060: flags 0x00 
LOCK_ONLY EXCL_LOCK KEYS_UPDATED , blkref #0: rel 1663/19243/19560 blk 
540 FPW
rmgr: Heap        len (rec/tot):     99/    99, tx:    2045060, lsn: 
2/94026D80, prev 2/94025150, desc: UPDATE off 41 xmax 2045060 flags 0x61 
KEYS_UPDATED ; new off 5 xmax 2045060, blkref #0: rel 1663/19243/19560 
blk 540
rmgr: Heap2       len (rec/tot):     58/    58, tx:          0, lsn: 
2/94031F28, prev 2/94031EF8, desc: PRUNE latestRemovedXid 2045060 
nredirected 0 ndead 1 nunused 1, unused: [41], dead: [57], blkref #0: 
rel 1663/19243/19560 blk 540
rmgr: Heap        len (rec/tot):     54/    54, tx:    2045062, lsn: 
2/94031F68, prev 2/94031F28, desc: LOCK off 5: xid 2045062: flags 0x00 
LOCK_ONLY EXCL_LOCK , blkref #0: rel 1663/19243/19560 blk 540
rmgr: Heap        len (rec/tot):     83/    83, tx:    2045062, lsn: 
2/94031FA0, prev 2/94031F68, desc: HOT_UPDATE off 5 xmax 2045062 flags 
0x60 ; new off 22 xmax 2045062, blkref #0: rel 1663/19243/19560 blk 540
rmgr: Heap2       len (rec/tot):     58/    58, tx:          0, lsn: 
2/94043C50, prev 2/94043C28, desc: PRUNE latestRemovedXid 2045062 
nredirected 1 ndead 0 nunused 0, redirected: [5->22], blkref #0: rel 
1663/19243/19560 blk 540
rmgr: Heap        len (rec/tot):     73/  8133, tx:    2065110, lsn: 
2/97207F18, prev 2/97207EE0, desc: UPDATE off 8 xmax 2065110 flags 0x00 
; new off 41 xmax 2065110, blkref #0: rel 1663/19243/19560 blk 540 FPW, 
blkref #1: rel 1663/19243/19560 blk 318
rmgr: Heap2       len (rec/tot):     53/  8109, tx:          0, lsn: 
2/97ED2598, prev 2/97ED2558, desc: VACUUM nunused 1, blkref #0: rel 
1663/19243/19560 blk 540 FPW
rmgr: Heap2       len (rec/tot):     59/    59, tx:          0, lsn: 
2/97ED4560, prev 2/97ED2598, desc: VISIBLE cutoff xid 2065110 flags 
0x01, blkref #0: rel 1663/19243/19560 fork vm blk 0, blkref #1: rel 
1663/19243/19560 blk 540
rmgr: Heap        len (rec/tot):     59/  8115, tx:    2085600, lsn: 
2/A0165A70, prev 2/A0165A38, desc: LOCK off 22: xid 2085600: flags 0x00 
LOCK_ONLY EXCL_LOCK KEYS_UPDATED , blkref #0: rel 1663/19243/19560 blk 
540 FPW
rmgr: Heap        len (rec/tot):     54/    54, tx:    2085600, lsn: 
2/A018E858, prev 2/A018D7D8, desc: LOCK off 22: xid 2085600: flags 0x00 
LOCK_ONLY EXCL_LOCK KEYS_UPDATED , blkref #0: rel 1663/19243/19560 blk 540
rmgr: Heap        len (rec/tot):     73/  8237, tx:    2085600, lsn: 
2/A018E890, prev 2/A018E858, desc: UPDATE off 22 xmax 2085600 flags 0x03 
KEYS_UPDATED ; new off 21 xmax 2085600, blkref #0: rel 1663/19243/19560 
blk 328 FPW, blkref #1: rel 1663/19243/19560 blk 540
rmgr: Heap2       len (rec/tot):     58/    58, tx:    2085602, lsn: 
2/A019DC20, prev 2/A019BC08, desc: PRUNE latestRemovedXid 2085600 
nredirected 0 ndead 1 nunused 1, unused: [22], dead: [5], blkref #0: rel 
1663/19243/19560 blk 540


-- 
K. R.