Re: explain format json, unit for serialize and memory are different.

[jian he]

On Wed, May 15, 2024 at 10:13 AM David Rowley <dgrowle...@gmail.com> wrote:
>
> On Wed, 15 May 2024 at 13:44, jian he <jian.universal...@gmail.com> wrote:
> >        "Shared Hit Blocks": 0,
> >        "Shared Read Blocks": 0,
> >        "Shared Dirtied Blocks": 0,
> >        "Shared Written Blocks": 0,
> >        "Local Hit Blocks": 0,
> >        "Local Read Blocks": 0,
> >        "Local Dirtied Blocks": 0,
> >        "Local Written Blocks": 0,
> >        "Temp Read Blocks": 0,
> >        "Temp Written Blocks": 0
> >
> > these information duplicated for json key "Serialization" and json key
> > "Planning"
> > i am not sure this is intended?
>
> Looks ok to me.  Buffers used during planning are independent from the
> buffers used when outputting rows to the client.
>

looking at serializeAnalyzeReceive.
I am not sure which part of serializeAnalyzeReceive will update pgBufferUsage.

I am looking for an example where this information under json key
"Serialization" is not zero.
So far I have tried:

create table s(a text);
insert into s select repeat('a', 1024) from generate_series(1,1024);
explain (format json, analyze, wal, buffers, memory, serialize, timing
off)  select * from s;