Re: HS and clog

Simon Riggs <simon(at)2ndQuadrant(dot)com> writes:
> On 30 March 2013 18:20, Andres Freund <andres(at)2ndquadrant(dot)com> wrote:
>> Imo this shouldn't be needed.

> In principle, I think your premise looks correct. ExtendCLOG() is not needed.

> If the xid truly is "known assigned" at a point in time, then the clog
> should already have been extended to allow that.

IIRC, the slru/clog code assumes, or at least did at one time assume,
that requests to initialize new pages are consecutive after startup.
Which is OK in normal operation since we don't skip over assignment
of any XIDs.

What I thought Andres was worried about here was that there might be
a gap in the extension requests when doing HS replay, and that maybe
that led to failure to create files or portions of files that later
the code would try to reference.

But maybe I misunderstood.

regards, tom lane