Hi,
Based on the investigation and (lack of) progress so far, I'll revert
part of the COPY FREEZE improvements shortly. I'll keep the initial
7db0cd2145 changes, tweaking heap_multi_insert, and remove most of
39b66a91bd (except for the heap_xlog_multi_insert bit).
This should address the small 5% regression in refresh matview. I have
no other ideas how to fix that, short of adding a user-level option to
REFRESH MATERIALIZED VIEW command so that the users can opt out/in.
Attached is the revert patch - I'll get it committed in the next day or
two, once the tests complete (running with CCA so it takes time).
regards
On 5/25/21 12:30 AM, Tomas Vondra wrote:
> On 5/24/21 8:21 PM, Andres Freund wrote:
>> Hi,
>>
>> On 2021-05-24 12:37:18 +0200, Tomas Vondra wrote:
>>> Another option might be changes in the binary layout - 5% change is well
>>> within the range that could be attributed to this, but it feels very
>>> hand-wavy and more like an excuse than real analysis.
>>
>> I don't think 5% is likely to be explained by binary layout unless you
>> look for an explicitly adverse layout.
>>
>
> Yeah, true. But I'm out of ideas what might be causing the regression
> and how to fix it :-(
>
>>
>>> Hmmm, thanks for reminding us that patch. Why did we reject that approach in
>>> favor of the current one?
>>
>> Don't know about others, but I think it's way too fragile.
>>
>
> Is it really that fragile? Any particular risks you have in mind? Maybe
> we could protect against that somehow ... Anyway, that change would
> certainly be for PG15.
>
>
> regards
>
--
Tomas Vondra
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