Re: [PATCH] Runtime control of CLOBBER_CACHE_ALWAYS

On 27.10.2020 11:34, Peter Eisentraut wrote:
> On 2020-09-25 09:40, Craig Ringer wrote:
>> While working on extensions I've often wanted to enable cache 
>> clobbering for a targeted piece of code, without paying the price of 
>> running it for all backends during postgres startup and any initial 
>> setup tasks that are required.
>>
>> So here's a patch that, when CLOBBER_CACHE_ALWAYS or 
>> CLOBBER_CACHE_RECURSIVE are defined, adds a GUC named 
>> clobber_cache_depth . It defaults to 1 for CLOBBER_CACHE_ALWAYS or 3 
>> for CLOBBER_CACHE_RECURSIVE to match the existing compiled-in 
>> behaviour. But with this change it's now possible to run Pg with 
>> clobber_cache_depth=0 then set it to 1 only for targeted tests.
>>
>> clobber_cache_depth is treated as an unknown GUC if Pg was not built 
>> with CLOBBER_CACHE_ALWAYS or CLOBBER_CACHE_RECURSIVE defined.
>
> I think it would be great if the cache clobber code is always compiled 
> in (but turned off) when building with assertions.  The would reduce 
> the number of hoops to jump through to actually use this locally and 
> reduce the number of surprises from the build farm.
>
> For backward compatibility, you can arrange it so that the built-in 
> default of clobber_cache_depth is 1 or 3 if CLOBBER_CACHE_ALWAYS or 
> CLOBBER_CACHE_RECURSIVE are defined.
>

Status update for a commitfest entry.

This thread was inactive during the commitfest, so I am going to mark it 
as "Returned with Feedback".
Craig, are you planning to continue working on it? The proposed idea is 
great and it looks like the patch needs only a minor improvement.

-- 
Anastasia Lubennikova
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company