| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Hiroshi Inoue <Inoue(at)tpf(dot)co(dot)jp> |
| Cc: | Vadim Mikheev <vmikheev(at)sectorbase(dot)com>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Possible bug in vacuum redo |
| Date: | 2001-12-24 01:28:04 |
| Message-ID: | 5781.1009157284@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Hiroshi Inoue <Inoue(at)tpf(dot)co(dot)jp> writes:
> In READ COMMITTED mode, an app searches valid tuples first
> using the snapshot taken when the query started. It never
> searches already updated(to newer ones) and committed tuples
> at the point when the query started. Essentially t_ctid is
> only needed by the concurrently running backends.
[ thinks for awhile ] I see: you're saying that t_ctid is only
used by transactions that are concurrent with the deleting transaction,
so if there's a database crash there's no need to restore t_ctid.
Probably true, but still mighty ugly.
Meanwhile, I guess I gotta look elsewhere for a theory to explain
those reports of duplicate rows. Oh well...
regards, tom lane
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