Subject: Re: [HACKERS] logical decoding of two-phase transactions
To: Nikhil Sontakke <nikhils@2ndquadrant.com>,
 Simon Riggs <simon@2ndquadrant.com>
References: <A434797D-1283-42C5-8CE5-7F1CD0B68F36@postgrespro.ru>
 <CAMsr+YF4QfAKzsfHQ7MS+5NG3aY-NG3T_DdhcdPEPkWD4fo7fQ@mail.gmail.com>
 <CAMGcDxf83P5SGnGH52=_0wRP9pO6uRWCMRwAA0nxKtZvir2_vQ@mail.gmail.com>
 <CAMsr+YGX1z5t_MccrJxd4VJPgZKx17EsAQcAQ_1iJ4dKDp0LOg@mail.gmail.com>
 <CAMGcDxeDd4uB+tvaYrtjLgykeOpa-5nwPetNM+prCQ=wpPmPaQ@mail.gmail.com>
 <CAMsr+YH_x7Lrz3arUewzAk4=FZ-+hdum-eW7gZJBAEmzo937eg@mail.gmail.com>
 <e55b1240-df0b-c5eb-bcdb-18902cdf42f8@2ndquadrant.com>
 <CAMsr+YGE84n5_1Z=xNwaRxS3Fx6WS7=FLcYtezt1wRx7VNjW0Q@mail.gmail.com>
 <CAMGcDxfin6iYuHN1_21Z7YYvPDU9qLgfBSBYti1KWiUUpJBr7g@mail.gmail.com>
 <CAMGcDxf0YDPxgG3sU=0k8zTZniEe2RhT90v4BP__3a1P4iHpEQ@mail.gmail.com>
 <45525c30-4002-861e-a82c-3b95b19d1514@2ndquadrant.com>
 <f351fc25-7b4d-3bf3-0398-d8a55bb3bd87@2ndquadrant.com>
 <CAMGcDxc0+17=5jZ7CXPpZFT9ugwLNXzPcht2J9EbaR-dXrDXCQ@mail.gmail.com>
 <CANP8+jKwhA9cofuUPP_OxEgy_2k3-LHBxw9E57MnBiS1U-3xVw@mail.gmail.com>
 <CAMGcDxca0zLfpMWTUV+1QT2NjZw+w2Zfzc2NKGfOH41UwFjQmw@mail.gmail.com>
Cc: Craig Ringer <craig@2ndquadrant.com>,
 Petr Jelinek <petr.jelinek@2ndquadrant.com>,
 Sokolov Yura <y.sokolov@postgrespro.ru>,
 Stas Kelvich <s.kelvich@postgrespro.ru>, Andres Freund <andres@anarazel.de>,
 Dmitry Dolgov <9erthalion6@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>,
 Masahiko Sawada <sawada.mshk@gmail.com>,
 PostgreSQL Hackers <pgsql-hackers@postgresql.org>,
 Robert Haas <robertmhaas@gmail.com>
From: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>
Organization: 2ndQuadrant
Message-ID: <dec39ab4-cc36-e01c-7a00-0087fe8644da@2ndquadrant.com>
Date: Tue, 19 Dec 2017 14:52:00 -0500
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.13; rv:52.0)
 Gecko/20100101 Thunderbird/52.5.0
MIME-Version: 1.0
In-Reply-To: 
 <CAMGcDxca0zLfpMWTUV+1QT2NjZw+w2Zfzc2NKGfOH41UwFjQmw@mail.gmail.com>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Precedence: bulk

On 12/19/17 03:37, Nikhil Sontakke wrote:
> 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?

-- 
Peter Eisentraut              http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services