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From: Tom Lane <[email protected]>
To: Tomas Vondra <[email protected]>
Cc: Jakub Wartak <[email protected]>
Cc: Robert Haas <[email protected]>
Cc: PostgreSQL Hackers <[email protected]>
Cc: Andres Freund <[email protected]>
Subject: Re: scalability bottlenecks with (many) partitions (and more)
Date: Sun, 22 Sep 2024 19:06:46 -0400
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
References: <[email protected]>
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Tomas Vondra <[email protected]> writes:
> On 9/22/24 17:45, Tom Lane wrote:
>> #define FAST_PATH_GROUP(index)	\
>> -	(AssertMacro(((index) >= 0) && ((index) < FP_LOCK_SLOTS_PER_BACKEND)), \
>> +	(AssertMacro((uint32) (index) < FP_LOCK_SLOTS_PER_BACKEND), \
>> ((index) / FP_LOCK_SLOTS_PER_GROUP))

> For the (x >= 0) asserts, doing it this way relies on negative values
> wrapping to large positive ones, correct? AFAIK it's guaranteed to be a
> very large value, so it can't accidentally be less than the slot count.

Right, any negative value would wrap to something more than
INT32_MAX.

			regards, tom lane

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