| From: | Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com> |
|---|---|
| To: | Simon Riggs <simon(at)2ndQuadrant(dot)com> |
| Cc: | pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Sync Replication with transaction-controlled durability |
| Date: | 2010-09-15 08:54:32 |
| Message-ID: | 4C9089C8.6090508@enterprisedb.com |
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| Lists: | pgsql-hackers |
On 14/09/10 20:48, Simon Riggs wrote:
> When each new messages arrives from master the WALreceiver will write
> the new data to the WAL file, wake the WALwriter and then reply. Each
> new message from master receives a reply. If no further WAL data has
> been received the WALreceiver waits on the latch. If the WALReceiver is
> woken by WALWriter or Startup then it will reply to master with a
> message, even if no new WAL has been received.
Wrt. the earlier discussion about when the standby sends the
acknowledgment, this is the key paragraph. So you *are* sending multiple
acknowledgments per transaction, but there is some smarts to combine
them when there's a lot of traffic. Fair enough.
--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com
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