Tom Lane wrote:
Cott Lang <[EMAIL PROTECTED]> writes:
Fiddling with the above values, only setting sort_mem absurdly large
easily causes NAN.
Ah. I see an overflow case for sort_mem exceeding 1Gb; that's probably
what you tickled.
I've fixed this in HEAD, but it doesn't seem worth back-patching.
If you care, the change in HEAD is
*** src/backend/optimizer/path/costsize.c.orig Sun Aug 29 01:06:43 2004
--- src/backend/optimizer/path/costsize.c Fri Oct 22 20:02:39 2004
***************
*** 566,572 ****
if (nbytes > work_mem_bytes)
{
double npages = ceil(nbytes / BLCKSZ);
! double nruns = nbytes / (work_mem_bytes * 2);
double log_runs = ceil(LOG6(nruns));
double npageaccesses;
--- 566,572 ----
if (nbytes > work_mem_bytes)
{
double npages = ceil(nbytes / BLCKSZ);
! double nruns = (nbytes / work_mem_bytes) * 0.5;
double log_runs = ceil(LOG6(nruns));
double npageaccesses;
but the variable names have changed since 7.4 so this won't apply
cleanly.
If somebody care about apply this for 7.4, here there is the equivalent change:
--- costsize.c.orig 2004-10-23 11:17:38.000000000 +0200
+++ costsize.c 2004-10-23 11:19:04.000000000 +0200
@@ -548,7 +548,7 @@
if (nbytes > sortmembytes)
{
double npages = ceil(nbytes / BLCKSZ);
- double nruns = nbytes / (sortmembytes * 2);
+ double nruns = ( nbytes / sortmembytes ) * 0.5 ;
double log_runs = ceil(LOG6(nruns));
double npageaccesses;
Regards
Gaetano Mendola
---------------------------(end of broadcast)---------------------------
TIP 1: subscribe and unsubscribe commands go to [EMAIL PROTECTED]
