Message-ID: <099cc1b8-c4bd-486a-876d-35c187ee4a1d@enterprisedb.com>
Date: Tue, 20 Feb 2024 12:18:46 +0100
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Subject: Re: Change the bool member of the Query structure to bits
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To: Quan Zongliang <quanzongliang@yeah.net>,
 pgsql-hackers@lists.postgresql.org
References: <d05a1c87-82e9-49a3-a4e2-e0d2b38b2e8b@yeah.net>
 <dc6fef8c-a702-43f1-8490-ed6c8408e712@yeah.net>
From: Tomas Vondra <tomas.vondra@enterprisedb.com>
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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

-- 
Tomas Vondra
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