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

On Wed, 15 May 2024 at 15:40, jian he <jian.universality@gmail.com> wrote:
> I am looking for an example where this information under json key
> "Serialization" is not zero.
> So far I have tried:

Something that requires detoasting.

> 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;

Something bigger than 1024 bytes or use SET STORAGE EXTERNAL or EXTENDED.

create table s(a text);
insert into s select repeat('a', 1024*1024) from generate_series(1,10);
explain (format text, analyze, buffers, serialize, timing off)  select * from s;

 Serialization: output=10241kB  format=text
   Buffers: shared hit=36

David