| From: | Hannu Krosing <hannuk(at)google(dot)com> |
|---|---|
| To: | Nikita Malakhov <hukutoc(at)gmail(dot)com> |
| Cc: | Michael Paquier <michael(at)paquier(dot)xyz>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>, Dilip Kumar <dilipkumarb(at)google(dot)com>, Matthias van de Meent <boekewurm+postgres(at)gmail(dot)com>, Yugo Nagata <nagata(at)sraoss(dot)co(dot)jp> |
| Subject: | Re: Direct TOAST v2, faster, smaller and no migration needed |
| Date: | 2026-09-07 09:15:06 |
| Message-ID: | CAMT0RQR2Fh8DQsOL=Mv90CBv856pDry5TQTsT3KfEZ=Y9=bJPA@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Mon, Sep 7, 2026 at 10:54 AM Hannu Krosing <hannuk(at)google(dot)com> wrote:
>
> The slowness of 1GB datum test in previous email is likely just
> because of more levels in toast inex, as it should fit well into
> shared buffers
>
> table_name │ table_size │ toast_table_size │ toast_index_size │
> ──────────────────────────┼──────────────┼──────────────────┼──────────────────┼
> public.largeplaintoast │ 11527708672 │ 11399487488 │ 125042688 │
> public.largedirecttoast │ 11495727104 │ 11492515840 │ 8192 │
>
> Time: 8.935 ms
> dtoast=# show shared_buffers;
> shared_buffers
> ────────────────
> 8GB
> (1 row)
Looks like this was caused by something else pushing data out of shared buffers.
Once thee index (and most data) was there, plain toast was as fast as
direct toast also on 1GB reads.
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