Buildfarm says we get different plans on 32-bit and 64-bit platforms,
probably because of MAXALIGN-related differences in memory-consumption
calculations. Add some dummy WHERE clauses so that the planner estimates
different sizes for the three generate_series() relations; that should
stabilize the choice of join order.
This is needed to allow ORDER BY, DISTINCT, etc to work as expected for
pg_lsn values.
We had previously decided to put this off for 9.5, but in view of commit
eeca4cd35e there's no reason to avoid a
catversion bump for 9.4beta2, and this does make a pretty significant
usability difference for pg_lsn.
Michael Paquier, with fixes from Andres Freund and Tom Lane
