Internal pointers clobbered on system crash without fsync???

If one runs Postgresql with fsync turned off in order to get better
performance, is there a risk that the database internals will be
damaged by a system crash? I realize that database discrepancies are
possible, but I am referring to a failure where storage allocation
gets messed up, or critical internal pointers get mangled, or
something like that.

What I have been able to find so far only addresses data
discrepancies, which are something that we can live with (IF WE REALLY
HAVE TO).

Also, if one uses raw disk instead of files, will Postgresql work
better with or without fsync?

For that matter, how does Postgresql with fsync turned on compare
performance/wise to Informix/Oracle for typical OLTP (95% read 5%
write) work?

Thanks in advance

John Moore

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