| From: | Heikki Linnakangas <hlinnaka(at)iki(dot)fi> |
|---|---|
| To: | Petr Jelinek <petr(at)2ndquadrant(dot)com>, Simon Riggs <simon(dot)riggs(at)2ndquadrant(dot)com> |
| Cc: | Andres Freund <andres(at)anarazel(dot)de>, Robert Haas <robertmhaas(at)gmail(dot)com>, Steve Singer <steve(at)ssinger(dot)info>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Replication identifiers, take 4 |
| Date: | 2015-04-20 08:09:20 |
| Message-ID: | 5534B430.4090301@iki.fi |
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| Lists: | pgsql-hackers |
On 04/17/2015 11:45 PM, Petr Jelinek wrote:
>> >The argument to move to 4 bytes is a poor one. If it was reasonable in
>> >terms of code or cosmetic value then all values used in the backend
>> >would be 4 bytes. We wouldn't have any 2 byte values anywhere. But we
>> >don't do that.
>> >
>> >The change does nothing useful, since I doubt anyone will ever need
>> > >32768 nodes in their cluster.
>> >
> And if they did there would be other much bigger problems than
> replication identifier being 16bit (it's actually >65534 as it's
> unsigned btw).
Can you name some of the bigger problems you'd have?
Obviously, if you have 100000 high-volume OLTP nodes connected to a
single server, feeding transactions as a continous stream, you're going
to choke the system. But you might have 100000 tiny satellite databases
that sync up with the master every few hours, and each of them do only a
few updates per day.
- Heikki
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