On 24 May 2012 12:42, Magnus Hagander <magnus@hagander.net> wrote:
> What actually happens if it tries to repalloc() something huge? palloc
> will throw an elog(ERROR), and since this happens during postmaster
> startup, are you sure it won't prevent the server from starting?
Oh, yes, missed that.
/* Previous incarnation might have had a larger query_size */ if (temp.query_len >= buffer_size) {
buffer= (char *) repalloc(buffer, temp.query_len + 1); buffer_size = temp.query_len + 1; }
Here, "temp" receives its value from an fread().
This could probably be coded to be defensive against such things, but
a better fix would be preferred. I have to wonder how much of a
problem corruption is likely to be though, given that we only save to
disk in a corresponding pgss_shmem_shutdown() call, which actually has
more protections against corruption. The window for the saved file to
be corrupt seems rather small, though I accept that a better window
would be zero.
--
Peter Geoghegan http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training and Services