| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | "Zeugswetter Andreas SB SD" <ZeugswetterA(at)spardat(dot)at> |
| Cc: | "Jan Wieck" <JanWieck(at)Yahoo(dot)com>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: tuptoaster.c must *not* use SnapshotAny |
| Date: | 2002-01-17 14:22:36 |
| Message-ID: | 23314.1011277356@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
"Zeugswetter Andreas SB SD" <ZeugswetterA(at)spardat(dot)at> writes:
>> It doesn't matter whether it's FrozenXid or not. The tuple is not
>> visible if it's got the wrong setting of HEAP_MOVED_OFF/IN.
> But the FrozenXid tuple has HEAP_MOVED_IN and the original has
> not yet been altered to HEAP_MOVED_OFF because of abort.
> Is the HEAP_MOVED_IN tuple not visible ?
Right. Actually it doesn't matter whether the old tuple has
HEAP_MOVED_OFF or not; it's still visible *until* the VACUUM commits.
The commit atomically switches us from the state where the unmoved
tuples are good to the state where the moved ones are good.
This is all exactly the same whether FrozenXid is involved or not.
regards, tom lane
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