mirror of
https://github.com/postgres/postgres.git
synced 2025-04-22 23:02:54 +03:00
517db49455
The planner largely failed to consider the possibility that a PlaceHolderVar's expression might contain a lateral reference to a Var coming from somewhere outside the PHV's syntactic scope. We had a previous report of a problem in this area, which I tried to fix in a quick-hack way in commit 4da6439bd8553059766011e2a42c6e39df08717f, but Antonin Houska pointed out that there were still some problems, and investigation turned up other issues. This patch largely reverts that commit in favor of a more thoroughly thought-through solution. The new theory is that a PHV's ph_eval_at level cannot be higher than its original syntactic level. If it contains lateral references, those don't change the ph_eval_at level, but rather they create a lateral-reference requirement for the ph_eval_at join relation. The code in joinpath.c needs to handle that. Another issue is that createplan.c wasn't handling nested PlaceHolderVars properly. In passing, push knowledge of lateral-reference checks for join clauses into join_clause_is_movable_to. This is mainly so that FDWs don't need to deal with it. This patch doesn't fix the original join-qual-placement problem reported by Jeremy Evans (and indeed, one of the new regression test cases shows the wrong answer because of that). But the PlaceHolderVar problems need to be fixed before that issue can be addressed, so committing this separately seems reasonable.
The PostgreSQL contrib tree
---------------------------
This subtree contains porting tools, analysis utilities, and plug-in
features that are not part of the core PostgreSQL system, mainly
because they address a limited audience or are too experimental to be
part of the main source tree. This does not preclude their
usefulness.
User documentation for each module appears in the main SGML
documentation.
When building from the source distribution, these modules are not
built automatically, unless you build the "world" target. You can
also build and install them all by running "gmake all" and "gmake
install" in this directory; or to build and install just one selected
module, do the same in that module's subdirectory.
Some directories supply new user-defined functions, operators, or
types. To make use of one of these modules, after you have installed
the code you need to register the new SQL objects in the database
system by executing a CREATE EXTENSION command. In a fresh database,
you can simply do
CREATE EXTENSION module_name;
See the PostgreSQL documentation for more information about this
procedure.