There are certain parts of code that laboriously initialize every field
of a struct to (some spelling of) zero, even though the whole struct was
just zeroed (by makeNode() or memset()) a few lines earlier. Besides
being redundant, I find this hard to read in some situations because
it's then very hard to tell what is different between different cases or
branches. The attached patch cleans up most of that. I left alone
instances where there are (nontrivial) comments attached to the
initializations or where there appeared to be some value in maintaining
symmetry. But a lot of it was just plain useless code, some clearly
copy-and-pasted repeatedly.
Note
<https://www.postgresql.org/message-id/flat/4c9f01be-9245-2148-b569-61a8562ef190(at)2ndquadrant(dot)com>
where we had a previous discussion about trimming down useless
initializations to zero.