Re: Global snapshots - Mailing list pgsql-hackers

From Robert Haas
Subject Re: Global snapshots
Date
Msg-id CA+Tgmob=fJo-pwGsnQT+PBoHyhNM4Giw3y5LXBm0YLhWvKEm1g@mail.gmail.com
Whole thread Raw
In response to Re: Global snapshots  (Stas Kelvich <s.kelvich@postgrespro.ru>)
Responses Re: Global snapshots  (Stas Kelvich <s.kelvich@postgrespro.ru>)
List pgsql-hackers
On Tue, May 1, 2018 at 5:02 PM, Stas Kelvich <s.kelvich@postgrespro.ru> wrote:
> Yes, that totally possible. On both systems you need:

Cool.

> * set track_global_snapshots='on' -- this will start writing each
>   transaction commit sequence number to SRLU.
> * set global_snapshot_defer_time to 30 seconds, for example -- this
>   will delay oldestXmin advancement for specified amount of time,
>   preserving old tuples.

So, is the idea that we'll definitely find out about any remote
transactions within 30 seconds, and then after we know about remote
transactions, we'll hold back OldestXmin some other way?

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company


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