Re: "snapshot too large" error when initializing logical replication (9.4)

On 2015-03-20 08:41:38 -0400, Bruce Momjian wrote:
> On Mon, Nov 17, 2014 at 03:52:38PM +0100, Andres Freund wrote:
> > On 2014-11-17 11:51:54 -0300, Alvaro Herrera wrote:
> > > Andres Freund wrote:
> > > > Hi,
> > > > 
> > > > On 2014-10-25 18:09:36 -0400, Steve Singer wrote:
> > > > > I sometimes get the error "snapshot too large" from my logical replication
> > > > > walsender process when in response to a CREATE_REPLICATION_SLOT.
> > > > 
> > > > Yes. That's possible if 'too much' was going on until a consistent point
> > > > was reached.  I think we can just use a much larger size for the array
> > > > if necessary.
> > > > 
> > > > I've attached patch for this. Could you try whether that helps? I don't
> > > > have a testcase handy that reproduces the problem.
> > > 
> > > You haven't pushed this, have you?
> > 
> > No, but it's on my todo list.
> 
> Uh, where are we on this?

Nowhere, unfortunately. The fix I'd developed isn't actually
correct. The problem is that we can only import a transaction with fewer
than GetMaxSnapshotXidCount() transactions atm.  The only reason it
worked in Steve's case is because he probably wasn't importin gthe
snapshot in the test case...

Greetings,

Andres Freund

-- Andres Freund                       http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training &
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