Douglas Trainor <trainor@uic.edu> writes:
> WARNING: Not sure if what I am about to describe is a bug.
As Scott comments, it isn't. Under *no* circumstances does Postgres
guarantee anything about the physical order of rows in a table.
This is entirely in accordance with the SQL spec --- row ordering is
not considered significant at all in the computational model. It's
worth noting that ORDER BY is treated by the spec as a mere output
decoration issue; you cannot ORDER the result of a sub-select, only
the final results being sent to the client. Fundamentally SQL does
not think row order is a valid consideration at all.
regards, tom lane