| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Alvaro Herrera <alvherre(at)commandprompt(dot)com> |
| Cc: | Jan Wieck <JanWieck(at)Yahoo(dot)com>, Merlin Moncure <mmoncure(at)gmail(dot)com>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: HeapTupleSatisfiesToast not setting XMIN_COMMITTED? |
| Date: | 2011-09-21 20:05:06 |
| Message-ID: | 28200.1316635506@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Alvaro Herrera <alvherre(at)commandprompt(dot)com> writes:
> More interesting, however, is the fact that the XMAX_COMMITTED bit is
> never set either. I guess the rows are deleted by a different mechanism
> (tuptoaster probably) -- it isn't obvious how this works just by looking
> at tqual.c. It seems to do nothing at all.
I have some vague recollection that the only reason we do any xmin/xmax
checking at all for a TOAST tuple is to support tuple motion caused by
old-style VACUUM FULL. Jan might remember better.
regards, tom lane
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