Re: Shared detoast Datum proposal - Mailing list pgsql-hackers

From Nikita Malakhov
Subject Re: Shared detoast Datum proposal
Date
Msg-id CAN-LCVMU_AzYNDQ-MgX3xc5qCnhTgO1LWKUCygOu3neBM-y94g@mail.gmail.com
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In response to Re: Shared detoast Datum proposal  (Andy Fan <zhihuifan1213@163.com>)
Responses Re: Shared detoast Datum proposal
List pgsql-hackers
Hi!

I see this to be a very promising initiative, but some issues come into my mind.
When we store and detoast large values, say, 1Gb - that's a very likely scenario,
we have such cases from prod systems - we would end up in using a lot of shared
memory to keep these values alive, only to discard them later. Also, toasted values
are not always being used immediately and as a whole, i.e. jsonb values are fully
detoasted (we're working on this right now) to extract the smallest value from
big json, and these values are not worth keeping in memory. For text values too,
we often do not need the whole value to be detoasted and kept in memory.

What do you think?

--
Regards,
Nikita Malakhov
Postgres Professional
The Russian Postgres Company

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