hi, all
I am so sorry for asking some questions like this!
Recently, for understanding postgresql's optimizer, I read and debug the source code. these two days, I read these macros in sysattr.h:
...
#define ObjectIdAttributeNumber (-2)
...
and the relative codes, but I still did not know why authors designed them like that, especially the value '-2' ?
what should I do if I want to see the thoughts behind them? thanks in advance!