Re: SLRUs in the main buffer pool - Page Header definitions - Mailing list pgsql-hackers

From Andres Freund
Subject Re: SLRUs in the main buffer pool - Page Header definitions
Date
Msg-id 20220622213943.drj7fni2usgo6owy@alap3.anarazel.de
Whole thread Raw
In response to SLRUs in the main buffer pool - Page Header definitions  ("Bagga, Rishu" <bagrishu@amazon.com>)
Responses Re: SLRUs in the main buffer pool - Page Header definitions
List pgsql-hackers
Hi,

On 2022-06-22 21:06:29 +0000, Bagga, Rishu wrote:
> 3. A flag to identify if the page is a relational or BufferedObject

Why is this needed in the page header?


> Using the new BufferedObject page header will be space efficient but
> introduces a significant change in the codebase to now track two types
> of page header data. During upgrade, all SLRU files that exist on the
> system must be converted to the new format with page header. This will
> require rewriting all the SLRU pages with the page header as part of
> pg_upgrade.

How are you proposing to deal with this in the "key" to "offset in SLRU"
mapping? E.g. converting a xid to an offset in the pg_xact SLRU. I assume
you're thinking to deal with this by making the conversion math a bit more
complicated?

Greetings,

Andres Freund



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