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Commit54a8abc

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Fix thinko in lock mode enum
Commit0e5680f contained a thinkomixing LOCKMODE with LockTupleMode. This caused misbehavior in the casewhere a tuple is marked with a multixact with at most a FOR SHARE lock,and another transaction tries to acquire a FOR NO KEY EXCLUSIVE lock;this case should block but doesn't.Include a new isolation tester spec file to explicitely try all thetuple lock combinations; without the fix it shows the problem: starting permutation: s1_begin s1_lcksvpt s1_tuplock2 s2_tuplock3 s1_commit step s1_begin: BEGIN; step s1_lcksvpt: SELECT * FROM multixact_conflict FOR KEY SHARE; SAVEPOINT foo; a 1 step s1_tuplock2: SELECT * FROM multixact_conflict FOR SHARE; a 1 step s2_tuplock3: SELECT * FROM multixact_conflict FOR NO KEY UPDATE; a 1 step s1_commit: COMMIT;With the fixed code, step s2_tuplock3 blocks until session 1 commits,which is the correct behavior.All other cases behave correctly.Backpatch to 9.3, like the commit that introduced the problem.
1 parenta68b8ae commit54a8abc

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4 files changed

+537
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‎src/backend/access/heap/heapam.c

Lines changed: 4 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -5924,6 +5924,7 @@ DoesMultiXactIdConflict(MultiXactId multi, uint16 infomask,
59245924
intnmembers;
59255925
MultiXactMember*members;
59265926
boolresult= false;
5927+
LOCKMODEwanted=tupleLockExtraInfo[lockmode].hwlock;
59275928

59285929
allow_old= !(infomask&HEAP_LOCK_MASK)&&HEAP_XMAX_IS_LOCKED_ONLY(infomask);
59295930
nmembers=GetMultiXactIdMembers(multi,&members,allow_old);
@@ -5934,11 +5935,12 @@ DoesMultiXactIdConflict(MultiXactId multi, uint16 infomask,
59345935
for (i=0;i<nmembers;i++)
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{
59365937
TransactionIdmemxid;
5937-
LockTupleModememlockmode;
5938+
LOCKMODEmemlockmode;
59385939

59395940
memlockmode=LOCKMODE_from_mxstatus(members[i].status);
5941+
59405942
/* ignore members that don't conflict with the lock we want */
5941-
if (!DoLockModesConflict(memlockmode,lockmode))
5943+
if (!DoLockModesConflict(memlockmode,wanted))
59425944
continue;
59435945

59445946
/* ignore members from current xact */

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