Message-ID: <954eace7-8fca-4a0e-b05c-2f907e2d081a@yeah.net>
Date: Wed, 21 Feb 2024 07:46:53 +0800
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Subject: Re: Change the bool member of the Query structure to bits
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To: Tomas Vondra <tomas.vondra@enterprisedb.com>,
 pgsql-hackers@lists.postgresql.org
References: <d05a1c87-82e9-49a3-a4e2-e0d2b38b2e8b@yeah.net>
 <dc6fef8c-a702-43f1-8490-ed6c8408e712@yeah.net>
 <099cc1b8-c4bd-486a-876d-35c187ee4a1d@enterprisedb.com>
From: Quan Zongliang <quanzongliang@yeah.net>
In-Reply-To: <099cc1b8-c4bd-486a-876d-35c187ee4a1d@enterprisedb.com>
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On 2024/2/20 19:18, Tomas Vondra wrote:
> On 2/20/24 11:11, Quan Zongliang wrote:
>>
>> Sorry. I forgot to save a file. This is the latest.
>>
>> On 2024/2/20 18:07, Quan Zongliang wrote:
>>>
>>> The Query structure has an increasing number of bool attributes. This
>>> is likely to increase in the future. And they have the same
>>> properties. Wouldn't it be better to store them in bits? Common
>>> statements don't use them, so they have little impact. This also saves
>>> memory space.
>>>
> 
> Hi,
> 
> Are we really adding bools to Query that often? A bit of git-blame says
> it's usually multiple years to add a single new flag, which is what I'd
> expect. I doubt that'll change.
> 
> As for the memory savings, can you quantify how much memory this would save?
> 
> I highly doubt that's actually true (or at least measurable). The Query
> struct has ~256B, the patch cuts that to ~232B. But we allocate stuff in
> power-of-2, so we'll allocate 256B chunk anyway. And we allocate very
> few of those objects anyway ...
> 
> regards
> 
That makes sense. Withdraw.