Skip collecting decoded changes of already-aborted transactions - Mailing list pgsql-hackers

From Masahiko Sawada
Subject Skip collecting decoded changes of already-aborted transactions
Date
Msg-id CAD21AoDht9Pz_DFv_R2LqBTBbO4eGrpa9Vojmt5z5sEx3XwD7A@mail.gmail.com
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Responses Re: Skip collecting decoded changes of already-aborted transactions  (Andres Freund <andres@anarazel.de>)
Re: Skip collecting decoded changes of already-aborted transactions  (Dilip Kumar <dilipbalaut@gmail.com>)
List pgsql-hackers
Hi,

In logical decoding, we don't need to collect decoded changes of
aborted transactions. While streaming changes, we can detect
concurrent abort of the (sub)transaction but there is no mechanism to
skip decoding changes of transactions that are known to already be
aborted. With the attached WIP patch, we check CLOG when decoding the
transaction for the first time. If it's already known to be aborted,
we skip collecting decoded changes of such transactions. That way,
when the logical replication is behind or restarts, we don't need to
decode large transactions that already aborted, which helps improve
the decoding performance.

Feedback is very welcome.

Regards,

--
Masahiko Sawada
Amazon Web Services: https://aws.amazon.com

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