| From: | Andrew Gierth <andrew(at)tao11(dot)riddles(dot)org(dot)uk> |
|---|---|
| To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Toast issues with OldestXmin going backwards |
| Date: | 2018-04-27 01:15:23 |
| Message-ID: | 87tvrxa210.fsf@news-spur.riddles.org.uk |
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| Thread: | |
| Lists: | pgsql-hackers |
>>>>> "Robert" == Robert Haas <robertmhaas(at)gmail(dot)com> writes:
Robert> I wonder if perhaps get_actual_variable_range() has a hazard of
Robert> this type as well. If OldestXmin retreats, then the special
Robert> snapshot type which it uses could see a row whose TOAST entry
Robert> has been removed meanwhile.
Actually get_actual_variable_range may have a hazard even if OldestXmin
does not retreat; it uses RecentGlobalXmin, which is quite likely to be
older than an OldestXmin value used by a vacuum.
--
Andrew (irc:RhodiumToad)
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