Message-ID: <77609a7a-4d7f-4c24-890a-5af9ebcfe9bd@vondra.me>
Date: Sat, 14 Mar 2026 15:53:21 +0100
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Subject: Re: Tighten asserts on ParallelWorkerNumber a little bit
To: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
References: <5db067a1-2cdf-4afb-a577-a04f30b69167@vondra.me>
 <abPsqcdVKcaK3XNS@ip-10-97-1-34.eu-west-3.compute.internal>
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From: Tomas Vondra <tomas@vondra.me>
In-Reply-To: <abPsqcdVKcaK3XNS@ip-10-97-1-34.eu-west-3.compute.internal>
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On 3/13/26 11:53, Bertrand Drouvot wrote:
> ...
>
>> So AFAICS the assert(s) should be
>>
>>   Assert(ParallelWorkerNumber < node->shared_info->num_workers);
> 
> I think that you're right. It looks like the first one has been introduced
> by bf11e7ee2e3 and then the others are probably copy/paste.
> 
>> I don't think we had issues with this not catching a bug. But it may be
>> a bit misleading, so worth fixing and (probably) backpatching.
> 
> I do agree.
> 
> With that patch applied, the remaining one:
> 
> $ git grep "<=.*num_workers"
> src/backend/executor/nodeGatherMerge.c: Assert(nreaders <= castNode(GatherMerge, gm_state->ps.plan)->num_workers);
> 
> does not need to be fixed, so I think that your patch does not miss any and
> LGTM.
> 

Thanks. Pushed and backpatched.

-- 
Tomas Vondra