Re: Transaction Snapshots and Hot Standby

On Fri, 2008-09-12 at 12:31 +0100, Richard Huxton wrote:
> There was a suggestion (Simon - from you?) of a transaction voluntarily
> restricting itself to a set of tables.

While thinking about how easy it would be for the DBA to specify the set
of tables a single query is accessing, first I thought that it should be
straight enough to look at the query itself for that. Then I thought
what about views, rules, triggers, user functions etc. ? All those have
the potential to access more than you see in the query itself. And then
the actually interesting question: what will the slave do with views,
rules, triggers ? I guess triggers are out of the question to be
executed, what about rules ? Probably must be also ignored... user
functions will probably get errors if they try to update something...
Views should probably function correctly.

So in any case the functionality available for querying slaves would be
less than for the primary. This is probably good enough for most
purposes...

Cheers,
Csaba.