random number seed each time. This is how it used to work years ago, but
we got rid of the seed reset because it was resetting the main random()
sequence and thus having undesirable effects on the rest of the system.
To fix, establish a private random number state for each execution of
geqo(), and initialize the state using the new GUC variable geqo_seed.
People who want to experiment with different random searches can do so
by changing geqo_seed, but you'll always get the same plan for the same
value of geqo_seed (if holding all other planner inputs constant, of course).
The new state is kept in PlannerInfo by adding a "void *" field reserved
for use by join_search hooks. Most of the rather bulky code changes in
this commit are just arranging to pass PlannerInfo around to all the GEQO
functions (many of which formerly didn't receive it).
Andres Freund, with some editorialization by Tom
Also performed an initial run through of upgrading our Copyright date to
extend to 2005 ... first run here was very simple ... change everything
where: grep 1996-2004 && the word 'Copyright' ... scanned through the
generated list with 'less' first, and after, to make sure that I only
picked up the right entries ...
that RAND_MAX applies to them, since it doesn't. Instead add a
config.h parameter MAX_RANDOM_VALUE. This is currently set at 2^31-1
but could be auto-configured if that ever proves necessary. Also fix
some outright bugs like calling srand() where srandom() is appropriate.
