Re: Planning incompatibilities for Postgres 10.0

Bruce Momjian wrote:
> On Mon, May 27, 2013 at 05:21:16PM -0700, Joshua D. Drake wrote:

> > I would like to see the ability to define if a query is read only at
> > the protocol level, so that load balances that speak libpq can know
> > what to do with the query without parsing it.
> 
> Sounds nice, but how would we do that?  That would require libpq to know
> it, right?  Do we pass anything back after parsing but before execution?
>  Could it be optional?  What about functions that modify the database
> --- isn't that only known at execution time?

Well, if you hit anything that tries to acquire an Xid, and you're in a
context that said only read-only was acceptable, just raise an error.

In a similar vein, I vaguely recall we discussed (after some security
vulnerability involving SQL injection) a mode where we only accept only
one command per PQexec() call, i.e. reject execution of commands that
contain multiple queries.

-- 
Álvaro Herrera                http://www.2ndQuadrant.com/
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