Re: ZStandard (with dictionaries) compression support for TOAST compression - Mailing list pgsql-hackers

From Nikita Malakhov
Subject Re: ZStandard (with dictionaries) compression support for TOAST compression
Date
Msg-id CAN-LCVMsmtxnEycec3SRxvCmwgbYTSkbF477Bsj7xT1zobwPig@mail.gmail.com
Whole thread Raw
In response to Re: ZStandard (with dictionaries) compression support for TOAST compression  (Nikhil Kumar Veldanda <veldanda.nikhilkumar17@gmail.com>)
List 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

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