result relation used anymore?
While learning how to read query trees, I have been puzzled by the
assertion in the manual that the :resultRelations of an INSERT holds
`the table (or view!) where the changes take effect,' because in all
of the INSERTs I have generated the resultRelation in fact appears
empty, and the destination of the INSERT appears as the first of the
range table entries. Do I misunderstand the query trees, or the
documentation, or both?
The documentation I quoted is at:
http://www3.us.postgresql.org/users-lounge/docs/7.3/postgres/querytree.html
--
Brandon Craig Rhodes http://www.rhodesmill.org/brandon
Georgia Tech brandon@oit.gatech.edu
Brandon Craig Rhodes <brandon@oit.gatech.edu> writes:
While learning how to read query trees, I have been puzzled by the
assertion in the manual that the :resultRelations of an INSERT holds
`the table (or view!) where the changes take effect,' because in all
of the INSERTs I have generated the resultRelation in fact appears
empty,
You seem to be confusing resultRelation with resultRelations. The
documentation is speaking of the former. Of the latter, parsenodes.h
says
/*
* If the resultRelation turns out to be the parent of an inheritance
* tree, the planner will add all the child tables to the rtable and
* store a list of the rtindexes of all the result relations here.
* This is done at plan time, not parse time, since we don't want to
* commit to the exact set of child tables at parse time. This field
* ought to go in some sort of TopPlan plan node, not in the Query.
*/
List *resultRelations; /* integer list of RT indexes, or NIL */
Note in particular that this only gets set when the target is an
inheritance tree --- which, by definition, it never is for INSERT.
regards, tom lane