Re: pgsql: Implement waiting for given lsn at transaction start - Mailing list pgsql-committers

From David G. Johnston
Subject Re: pgsql: Implement waiting for given lsn at transaction start
Date
Msg-id CAKFQuwYSscfbDNtQWHZY7Pin5WNPk1g7Z0qs_AfncVndeCOwLA@mail.gmail.com
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In response to Re: pgsql: Implement waiting for given lsn at transaction start  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: pgsql: Implement waiting for given lsn at transaction start  (Anna Akenteva <a.akenteva@postgrespro.ru>)
List pgsql-committers
On Tue, Apr 7, 2020 at 2:27 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
Alexander Korotkov <akorotkov@postgresql.org> writes:
> Implement waiting for given lsn at transaction start
> This commit adds following optional clause to BEGIN and START TRANSACTION
> commands.
>   WAIT FOR LSN lsn [ TIMEOUT timeout ]

This seems like a really carelessly chosen syntax --- *three* new
keywords, when you probably didn't need any.  Are you not aware that
there is distributed overhead in the grammar for every keyword?
Plus, each new keyword carries the risk of breaking existing
applications, since it no longer works as an alias-not-preceded-by-AS.

I have no particular opinion on the value of the feature, but I wish
a different syntax had been chosen.

I was curious whether the syntax got this kind of discussion, followed the discussion link, and the last email seen reads:

"""
> Worse, it was marked Needs Review even though no new patch was provided.
>
> I'm going to set this back to Returned with Feedback.  If anyone has a good
> reason that it should be in the CF we can always revive it.

+1.
"""

While there is lots of discussion it ended up with the thread at "returned with feedback" (a month ago) and now we have a commit.  There seems to be other relevant discussion not linked to.

David J.

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