Re: [HACKERS] Restricting maximum keep segments by repslots - Mailing list pgsql-hackers

From Andres Freund
Subject Re: [HACKERS] Restricting maximum keep segments by repslots
Date
Msg-id 20171106132050.6apzynxrqrzghb4r@alap3.anarazel.de
Whole thread Raw
In response to Re: [HACKERS] Restricting maximum keep segments by repslots  (Kyotaro HORIGUCHI <horiguchi.kyotaro@lab.ntt.co.jp>)
Responses Re: [HACKERS] Restricting maximum keep segments by repslots  (Kyotaro HORIGUCHI <horiguchi.kyotaro@lab.ntt.co.jp>)
List pgsql-hackers
Hi,

On 2017-10-31 18:43:10 +0900, Kyotaro HORIGUCHI wrote:
>   - distance:
>     how many bytes LSN can advance before the margin defined by
>     max_slot_wal_keep_size (and wal_keep_segments) is exhasuted,
>     or how many bytes this slot have lost xlog from restart_lsn.

I don't think 'distance' is a good metric - that's going to continually
change. Why not store the LSN that's available and provide a function
that computes this? Or just rely on the lsn - lsn operator?

- Andres


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