Re: pg_stat_statements temporary file

On 24 May 2012 12:42, Magnus Hagander <magnus(at)hagander(dot)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/
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