> I'd guess some WAL record arising  from the post-crash master restart makes 
> standby do so.  When a  crash isn't involved, the commit or abort record is 
> signal.  You  could test and find out how it happens after a master crash 
> with 
> procedure  like this:
> 1. Start a master and standby on the same machine.
> 2.  Connect to master; CREATE TABLE t(); BEGIN; ALTER TABLE t ADD c int;
> 3. kill  -9 -`head -n1 $master_PGDATA/postmaster.pid`
> 4. Connect to standby and  confirm that t is still locked.
> 5. Attach debugger to standby startup process  and set breakpoints on
> StandbyReleaseLocks and StandbyReleaseLocksMany.
> 6.  Restart master.

Well yes, based on the test the stack is something like:


It's not very clear to me what ProcArrayApplyRecoveryInfo does (not too
familiar with the standby part I guess) but I see it's called by xlog_redo in
the "info == XLOG_CHECKPOINT_SHUTDOWN" case and by StartupXLOG.

But I don't know if calling     ResetUnloggedRelations before 
the call to ProcArrayApplyRecoveryInfo in   xlog_redo makes sense...
if it makes sense, it would solve the problem of the stray files in
the master crashing case I guess?

> > > When you promote the standby,  though,  
> > ShutdownRecoveryTransactionEnvironment()
> > > releases the  locks.

If I understand the code, ResetUnloggedRelations is called before 
ShutdownRecoveryTransactionEnvironment, so that part shouldn't be
an issue 


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