BUG #17197: Assert failed on inserting index tuples after VACUUM

The following bug has been logged on the website:

Bug reference:      17197
Logged by:          Alexander Lakhin
Email address:      exclusion@gmail.com
PostgreSQL version: 14beta3
Operating system:   Ubuntu 20.04
Description:        

The following made-up query:
echo "create table parent1(f1 int, constraint f1chk check (f1>0));" >q.sql
{ for i in `seq 18`;    do echo "create table t$i(f2 int)
inherits(parent1);"; done } >>q.sql
{ for i in `seq 1200`;  do echo "alter table parent1 alter column f1 type
bigint;"; done } >>q.sql
echo "vacuum;" >>q.sql
{ for i in `seq 20 23`; do echo "create table t$i(f1 int primary key);";
done } >>q.sql;
# (Without a doubt, such state of an index could be achieved with a less
extravagant approach.)

Leads to an assertion failure with the following stack trace:
Core was generated by `postgres: law regression [local] CREATE TABLE        
                        '.
Program terminated with signal SIGABRT, Aborted.
#0  __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:50
50      ../sysdeps/unix/sysv/linux/raise.c: No such file or directory.
(gdb) bt
#0  __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:50
#1  0x00007f16181d9859 in __GI_abort () at abort.c:79
#2  0x000055672da7aa44 in ExceptionalCondition
(conditionName=conditionName@entry=0x55672dbb614d "false", 
    errorType=errorType@entry=0x55672dada00b "FailedAssertion",
fileName=0x7ffe13a0a770 "%\252\247-gU", 
    fileName@entry=0x55672dae546d "heapam.c",
lineNumber=lineNumber@entry=7489) at assert.c:69
#3  0x000055672d5cbc8a in heap_index_delete_tuples (rel=0x7f160cff1258,
delstate=0x7ffe13a0bcc0) at heapam.c:7489
#4  0x000055672d5f1d0f in table_index_delete_tuples
(delstate=0x7ffe13a0bcc0, rel=0xcc)
    at ../../../../src/include/access/tableam.h:1327
#5  _bt_delitems_delete_check (rel=rel@entry=0x7f160d062fd8,
buf=buf@entry=259, heapRel=heapRel@entry=0x7f160cff1258, 
    delstate=delstate@entry=0x7ffe13a0bcc0) at nbtpage.c:1541
#6  0x000055672d5e5c03 in _bt_simpledel_pass (rel=rel@entry=0x7f160d062fd8,
buffer=buffer@entry=259, 
    heapRel=heapRel@entry=0x7f160cff1258,
deletable=deletable@entry=0x7ffe13a0bd60, ndeletable=76, 
    newitem=<optimized out>, minoff=1, maxoff=204) at nbtinsert.c:2880
#7  0x000055672d5e5f2d in _bt_delete_or_dedup_one_page
(rel=rel@entry=0x7f160d062fd8, 
    heapRel=heapRel@entry=0x7f160cff1258,
insertstate=insertstate@entry=0x7ffe13a0c170, 
    simpleonly=simpleonly@entry=false,
checkingunique=checkingunique@entry=true, uniquedup=uniquedup@entry=false,

    indexUnchanged=false) at nbtinsert.c:2693
#8  0x000055672d5eb80b in _bt_findinsertloc (rel=rel@entry=0x7f160d062fd8,

    insertstate=insertstate@entry=0x7ffe13a0c170,
checkingunique=checkingunique@entry=true, 
    indexUnchanged=indexUnchanged@entry=false, stack=stack@entry=0x0,
heapRel=heapRel@entry=0x7f160cff1258)
    at nbtinsert.c:904
#9  0x000055672d5ebbda in _bt_doinsert (rel=rel@entry=0x7f160d062fd8,
itup=itup@entry=0x55672e2a71b0, 
    checkUnique=checkUnique@entry=UNIQUE_CHECK_YES,
indexUnchanged=indexUnchanged@entry=false, 
    heapRel=heapRel@entry=0x7f160cff1258) at nbtinsert.c:255
#10 0x000055672d5f2b97 in btinsert (rel=0x7f160d062fd8, values=<optimized
out>, isnull=<optimized out>, 
    ht_ctid=0x55672e2a66c4, heapRel=0x7f160cff1258,
checkUnique=UNIQUE_CHECK_YES, indexUnchanged=false, 
    indexInfo=0x55672e2a6e68) at nbtree.c:199
#11 0x000055672d5e0c9d in index_insert
(indexRelation=indexRelation@entry=0x7f160d062fd8, 
    values=values@entry=0x7ffe13a0c2e0, isnull=isnull@entry=0x7ffe13a0c2c0,

    heap_t_ctid=heap_t_ctid@entry=0x55672e2a66c4,
heapRelation=heapRelation@entry=0x7f160cff1258, 
    checkUnique=UNIQUE_CHECK_YES, indexUnchanged=false,
indexInfo=0x55672e2a6e68) at indexam.c:193
#12 0x000055672d667aac in CatalogIndexInsert
(indstate=indstate@entry=0x55672e328360, 
    heapTuple=heapTuple@entry=0x55672e2a66c0) at indexing.c:158
#13 0x000055672d667b84 in CatalogTupleInsert
(heapRel=heapRel@entry=0x7f160cff1258, tup=0x55672e2a66c0)
    at indexing.c:231
#14 0x000055672d67a465 in CreateConstraintEntry
(constraintName=constraintName@entry=0x55672e2a4580 "t22_pkey", 
    constraintNamespace=constraintNamespace@entry=2200,
constraintType=constraintType@entry=112 'p', 
    isDeferrable=isDeferrable@entry=false,
isDeferred=isDeferred@entry=false, isValidated=isValidated@entry=true, 
    parentConstrId=0, relId=39328, constraintKey=0x55672e2a306c,
constraintNKeys=1, constraintNTotalKeys=1, domainId=0, 
    indexRelId=39331, foreignRelId=0, foreignKey=0x0, pfEqOp=0x0,
ppEqOp=0x0, ffEqOp=0x0, foreignNKeys=0, 
    foreignUpdateType=32 ' ', foreignDeleteType=32 ' ', foreignMatchType=32
' ', exclOp=0x0, conExpr=0x0, conBin=0x0, 
    conIsLocal=true, conInhCount=0, conNoInherit=true, is_internal=false) at
pg_constraint.c:226
#15 0x000055672d6637af in index_constraint_create
(heapRelation=heapRelation@entry=0x7f160cff4b38, 
    indexRelationId=indexRelationId@entry=39331,
parentConstraintId=parentConstraintId@entry=0, 
    indexInfo=indexInfo@entry=0x55672e2a3060,
constraintName=constraintName@entry=0x55672e2a4580 "t22_pkey", 
    constraintType=<optimized out>, constr_flags=0,
allow_system_table_mods=false, is_internal=false) at index.c:1941
#16 0x000055672d666b95 in index_create
(heapRelation=heapRelation@entry=0x7f160cff4b38, 
    indexRelationName=indexRelationName@entry=0x55672e2a4580 "t22_pkey",
indexRelationId=39331, 
    indexRelationId@entry=0, parentIndexRelid=parentIndexRelid@entry=0,
parentConstraintId=parentConstraintId@entry=0, 
    relFileNode=0, indexInfo=0x55672e2a3060, indexColNames=0x55672e2a4728,
accessMethodObjectId=403, tableSpaceId=0, 
    collationObjectId=0x55672e2a47d0, classObjectId=0x55672e2a47f0,
coloptions=0x55672e2a4810, reloptions=0, flags=3, 
    constr_flags=0, allow_system_table_mods=false, is_internal=false,
constraintId=0x7ffe13a0ca00) at index.c:1057
#17 0x000055672d716f13 in DefineIndex (relationId=relationId@entry=39328,
stmt=stmt@entry=0x55672e311af0, 
    indexRelationId=indexRelationId@entry=0,
parentIndexId=parentIndexId@entry=0, 
    parentConstraintId=parentConstraintId@entry=0,
is_alter_table=is_alter_table@entry=false, check_rights=true, 
    check_not_in_use=true, skip_build=false, quiet=false) at
indexcmds.c:1137
#18 0x000055672d940e6a in ProcessUtilitySlow
(pstate=pstate@entry=0x55672e2a34f8, pstmt=pstmt@entry=0x55672e2a0270, 
    queryString=queryString@entry=0x55672e1a74d0 "create table t22(f1 int
primary key);", 
    context=context@entry=PROCESS_UTILITY_SUBCOMMAND,
params=params@entry=0x0, queryEnv=queryEnv@entry=0x0, 
    dest=0x55672dd6c740 <donothingDR>, qc=0x0) at utility.c:1534
#19 0x000055672d940388 in standard_ProcessUtility (pstmt=0x55672e2a0270, 
    queryString=0x55672e1a74d0 "create table t22(f1 int primary key);",
readOnlyTree=readOnlyTree@entry=false, 
    context=PROCESS_UTILITY_SUBCOMMAND, params=0x0, queryEnv=0x0,
dest=0x55672dd6c740 <donothingDR>, qc=0x0)
    at utility.c:1066
#20 0x000055672d940471 in ProcessUtility (pstmt=<optimized out>, 
    queryString=queryString@entry=0x55672e1a74d0 "create table t22(f1 int
primary key);", 
    readOnlyTree=readOnlyTree@entry=false,
context=context@entry=PROCESS_UTILITY_SUBCOMMAND, params=params@entry=0x0,

    queryEnv=queryEnv@entry=0x0, dest=0x55672dd6c740 <donothingDR>, qc=0x0)
at utility.c:527
#21 0x000055672d9407ae in ProcessUtilitySlow
(pstate=pstate@entry=0x55672e1c9560, pstmt=pstmt@entry=0x55672e1a8610, 
    queryString=queryString@entry=0x55672e1a74d0 "create table t22(f1 int
primary key);", 
    context=context@entry=PROCESS_UTILITY_TOPLEVEL, params=params@entry=0x0,
queryEnv=queryEnv@entry=0x0, 
    dest=0x55672e1a86e0, qc=0x7ffe13a0d3a0) at utility.c:1244
#22 0x000055672d940388 in standard_ProcessUtility (pstmt=0x55672e1a8610, 
    queryString=0x55672e1a74d0 "create table t22(f1 int primary key);",
readOnlyTree=<optimized out>, 
    context=PROCESS_UTILITY_TOPLEVEL, params=0x0, queryEnv=0x0,
dest=0x55672e1a86e0, qc=0x7ffe13a0d3a0)
    at utility.c:1066
#23 0x000055672d940471 in ProcessUtility (pstmt=pstmt@entry=0x55672e1a8610,
queryString=<optimized out>, 
    readOnlyTree=<optimized out>,
context=context@entry=PROCESS_UTILITY_TOPLEVEL, params=<optimized out>, 
    queryEnv=<optimized out>, dest=0x55672e1a86e0, qc=0x7ffe13a0d3a0) at
utility.c:527
#24 0x000055672d93d847 in PortalRunUtility
(portal=portal@entry=0x55672e209110, pstmt=pstmt@entry=0x55672e1a8610, 
    isTopLevel=isTopLevel@entry=true,
setHoldSnapshot=setHoldSnapshot@entry=false, dest=dest@entry=0x55672e1a86e0,

    qc=qc@entry=0x7ffe13a0d3a0) at pquery.c:1147
#25 0x000055672d93db4c in PortalRunMulti
(portal=portal@entry=0x55672e209110, isTopLevel=isTopLevel@entry=true, 
    setHoldSnapshot=setHoldSnapshot@entry=false,
dest=dest@entry=0x55672e1a86e0, altdest=altdest@entry=0x55672e1a86e0, 
    qc=qc@entry=0x7ffe13a0d3a0) at pquery.c:1304
#26 0x000055672d93df80 in PortalRun (portal=portal@entry=0x55672e209110,
count=count@entry=9223372036854775807, 
    isTopLevel=isTopLevel@entry=true, run_once=run_once@entry=true,
dest=dest@entry=0x55672e1a86e0, 
    altdest=altdest@entry=0x55672e1a86e0, qc=0x7ffe13a0d3a0) at
pquery.c:786
#27 0x000055672d93a17f in exec_simple_query (
    query_string=query_string@entry=0x55672e1a74d0 "create table t22(f1 int
primary key);") at postgres.c:1214
#28 0x000055672d93c15f in PostgresMain (argc=argc@entry=1,
argv=argv@entry=0x7ffe13a0d590, dbname=<optimized out>, 
    username=<optimized out>) at postgres.c:4486
#29 0x000055672d896c54 in BackendRun (port=port@entry=0x55672e1ca920) at
postmaster.c:4506
#30 0x000055672d899e3d in BackendStartup (port=port@entry=0x55672e1ca920) at
postmaster.c:4228
#31 0x000055672d89a076 in ServerLoop () at postmaster.c:1745
#32 0x000055672d89b5bd in PostmasterMain (argc=3, argv=<optimized out>) at
postmaster.c:1417
#33 0x000055672d7dbf20 in main (argc=3, argv=0x55672e1a1540) at main.c:209

Reproduced on REL_14_STABLE and master.
The first bad commit is 3c3b8a4b.