Re: [PATCH] Compression dictionaries for JSONB

Hi hackers!

Aleksander, please point me in the right direction if it was mentioned
before, I have a few questions:

1) It is not clear for me, how do you see the life cycle of such a
dictionary? If it is meant to keep growing without
cleaning up/rebuilding it could affect performance in an undesirable way,
along with keeping unused data without
any means to get rid of them.
Also, I agree with Simon Riggs, using OIDs from the general pool for
dictionary entries is a bad idea.

2) From (1) follows another question - I haven't seen any means for getting
rid of unused keys (or any other means
for dictionary cleanup). How could it be done?

3) Is the possible scenario legal - by some means a dictionary does not
contain some keys for entries? What happens then?

4) If one dictionary is used by several tables - I see future issues in
concurrent dictionary updates. This will for sure
affect performance and can cause unpredictable behavior for queries.

If you have any questions on Pluggable TOAST don't hesitate to ask me and
on JSONB Toaster you can ask Nikita Glukhov.

Thank you!

Regards,
Nikita Malakhov
Postgres Professional
https://postgrespro.ru/
On Mon, Jul 11, 2022 at 6:41 PM Aleksander Alekseev <
aleksander(at)timescale(dot)com> wrote:

> Hi hackers,
>
> > I invite anyone interested to join this effort as a co-author!
>
> Here is v5. Same as v4 but with a fixed compiler warning (thanks,
> cfbot). Sorry for the noise.
>
> --
> Best regards,
> Aleksander Alekseev
>