Re: Transaction Snapshots and Hot Standby

Simon Riggs wrote:
> 2. Master ignores Standby's OldestXmin
> Effects:
> * Long running queries on standby...
>    Have no effect on primary
>    Can delay apply of WAL records on standby
> * Queries on standby give consistent answers in all cases.

Just for clarification, if you set a max_slave_delay it means it is the
maximum amount of time WAL replay can be delayed on the slave, _and_ it
is the maximum amount of time a query/snapshot can be guaranteed to run
without the possibility of being canceled.  My point is that these two
concepts are linked to the same setting.

--  Bruce Momjian  <bruce@momjian.us>        http://momjian.us EnterpriseDB
http://enterprisedb.com
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