According to htup.h:
* t_self and t_tableOid should be valid if the HeapTupleData points
* to a disk buffer, or if it represents a copy of a tuple on disk.
* They should be explicitly set invalid in manufactured tuples.
In the heap_hot_search_buffer function of heapam.c this is not true.
I can't find a clear explanation of why that is. I'm assuming "it
just doesn't matter" here, but at a minimum it seems worth a
comment. It's not immediately obvious to me what the random garbage
from the stack would be replaced with if we were to try to make the
above comment true.
Quick brain dump on the topic, anyone?
-Kevin