| From: | Nikhil Sontakke <nikhils(at)2ndquadrant(dot)com> |
|---|---|
| To: | Peter Eisentraut <peter(dot)eisentraut(at)2ndquadrant(dot)com> |
| Cc: | Simon Riggs <simon(at)2ndquadrant(dot)com>, Craig Ringer <craig(at)2ndquadrant(dot)com>, Petr Jelinek <petr(dot)jelinek(at)2ndquadrant(dot)com>, Sokolov Yura <y(dot)sokolov(at)postgrespro(dot)ru>, Stas Kelvich <s(dot)kelvich(at)postgrespro(dot)ru>, Andres Freund <andres(at)anarazel(dot)de>, Dmitry Dolgov <9erthalion6(at)gmail(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>, Robert Haas <robertmhaas(at)gmail(dot)com> |
| Subject: | Re: [HACKERS] logical decoding of two-phase transactions |
| Date: | 2017-12-20 04:12:08 |
| Message-ID: | CAMGcDxfxEodz8+THwaXtjpW5WuBpeYp1t-UT9Wa-NfNuWaBVGA@mail.gmail.com |
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| Lists: | pgsql-hackers |
>> Note that this patch does not contain the HeapTupleSatisfiesVacuum
>> changes. I believe we need changes to HeapTupleSatisfiesVacuum given
>> than logical decoding changes the assumption that catalog tuples
>> belonging to a transaction which never committed can be reclaimed
>> immediately. With 2PC logical decoding or streaming logical decoding,
>> we can always have a split time window in which the ongoing decode
>> cycle needs those tuples. The solution is that even for aborted
>> transactions, we do not return HEAPTUPLE_DEAD if the transaction id is
>> newer than the OldestXmin (same logic we use for deleted tuples of
>> committed transactions). We can do this only for catalog table rows
>> (both system and user defined) to limit the scope of impact. In any
>> case, this needs to be a separate patch along with a separate
>> discussion thread.
>
> Are you working on that as well?
Sure, I was planning to work on that after getting the documentation
for this patch out of the way.
Regards,
Nikhils
--
Nikhil Sontakke http://www.2ndQuadrant.com/
PostgreSQL/Postgres-XL Development, 24x7 Support, Training & Services
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