| From: | Nikita Malakhov <hukutoc(at)gmail(dot)com> |
|---|---|
| To: | Nikhil Kumar Veldanda <veldanda(dot)nikhilkumar17(at)gmail(dot)com> |
| Cc: | Robert Haas <robertmhaas(at)gmail(dot)com>, Michael Paquier <michael(at)paquier(dot)xyz>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: ZStandard (with dictionaries) compression support for TOAST compression |
| Date: | 2025-04-29 10:36:51 |
| Message-ID: | CAN-LCVMsmtxnEycec3SRxvCmwgbYTSkbF477Bsj7xT1zobwPig@mail.gmail.com |
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| Thread: | |
| Lists: | pgsql-hackers |
Hi,
Nikhil, please consider existing discussions on using dictionaries
(mentioned above by Aleksander) and extending the TOAST pointer [1],
it seems you did not check them.
The same question Robert asked above - it's unclear why the header
wastes so much space. You mentioned metadata length - what metadata
do you mean there?
Also Robert pointed out very questionable approaches in your solution -
new dependencies crawling around user tables, new catalog table
with very unclear lifecycle (and, having new catalog table, immediately
having questions with pg_upgrade).
Currently I'm looking through the patch and could share my thoughts
later.
While reading this thread I've thought about storing a dictionary within
the table it is used for - IIUC on dictionary is used for just one
attribute,
so it does not make sense to make it global.
Also, I have a question regarding the Zstd implementation you propose -
does it provide a possibility for partial decompression?
>
>
Thanks!
--
Regards,
Nikita Malakhov
Postgres Professional
The Russian Postgres Company
https://postgrespro.ru/
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