Re: Removing unneeded self joins

Here is a current version of the patch, still rather experimental. Since
the previous version, I fixed some bugs and added the possibility to
remove a relation even when it is mentioned in target lists. I have to
rewrite all references to the removed relation in targetlists and the
equivalence classes, so that they point to the remaining relation. I
change RestrictInfos in place, and update attr_needed and reltarget of
the remaining relation. I also update equivalence members, and delete
equivalence classes that become single-member.

I'm posting it a single file now, because all meaningful changes are in
analyzejoins.c anyway.

--
Alexander Kuzmenkov
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company