Re: GSoC proposal - "make an unlogged table logged"

On 2014-03-03 12:08:26 -0500, Stephen Frost wrote:
> * Robert Haas (robertmhaas@gmail.com) wrote:
> > On Mon, Mar 3, 2014 at 11:28 AM, Fabrízio de Royes Mello
> > <fabriziomello@gmail.com> wrote:
> > > Is the TODO item "make an unlogged table logged" [1] a good GSoC project?
> >
> > I'm pretty sure we found some problems in that design that we couldn't
> > figure out how to solve.  I don't have a pointer to the relevant
> > -hackers discussion off-hand, but I think there was one.
>
> ISTR the discussion going something along the lines of "we'd have to WAL
> log the entire table to do that, and if we have to do that, what's the
> point?".

I don't see that as a particularly problematic problem. The primary
reason to want to convert a unlogged to a logged table probably is that
it's easier to do so than to recreate the table + dependencies. Also the
overhead of logging full pages will be noticeably smaller than the
overhead of adding all rows individually, even if using
heap_multi_insert().

Greetings,

Andres Freund

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