Date: Thu, 26 Sep 2019 23:46:06 +0200
From: Tomas Vondra <tomas.vondra@2ndquadrant.com>
To: Alvaro Herrera <alvherre@2ndquadrant.com>
Cc: Amit Kapila <amit.kapila16@gmail.com>,
	PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Subject: Re: PATCH: logical_work_mem and logical streaming of large
 in-progress transactions
Message-ID: <20190926214606.q6ad65r4umimc5w3@development>
References: <20190926175845.pau2qocmlffd37qg@development>
 <20190926193359.GA16585@alvherre.pgsql>
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On Thu, Sep 26, 2019 at 04:33:59PM -0300, Alvaro Herrera wrote:
>On 2019-Sep-26, Tomas Vondra wrote:
>
>> Hi,
>>
>> Attached is an updated patch series, rebased on current master. It does
>> fix one memory accounting bug in ReorderBufferToastReplace (the code was
>> not properly updating the amount of memory).
>
>Cool.
>
>Can we aim to get 0001 pushed during this commitfest, or is that a lost
>cause?
>

It's tempting. The patch has been in the queue for quite a bit of time,
and I think it's solid (at least 0001). I'll address the comments from
Peter's review about separating the GUC etc. and polish it a bit more.
If I manage to do that by Monday, I'll consider pushing it.

If anyone feels I shouldn't do that, let me know.

The one open question pointed out by Amit is how the patch picks the
trasction for eviction. My feeling is that's fine and if needed can be
improved later if necessary, but I'll try to construct a worst case
(max_connections xacts, each with 64 subxact) to verify.

>The large new comment in reorderbuffer.c says that a transaction might
>get spilled *or streamed*, but surely that second thing is not correct,
>since before the subsequent patches it's not possible to stream
>transactions that have not yet finished?
>

True. That's a residue of reordering the patch series repeatedly, I
think. I'll fix that while polishing the patch.


regards

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