pgsql: Fix up planner infrastructure to support LATERAL properly.

Fix up planner infrastructure to support LATERAL properly.

This patch takes care of a number of problems having to do with failure
to choose valid join orders and incorrect handling of lateral references
pulled up from subqueries. Notable changes:

* Add a LateralJoinInfo data structure similar to SpecialJoinInfo, to
represent join ordering constraints created by lateral references.
(I first considered extending the SpecialJoinInfo structure, but the
semantics are different enough that a separate data structure seems
better.) Extend join_is_legal() and related functions to prevent trying
to form unworkable joins, and to ensure that we will consider joins that
satisfy lateral references even if the joins would be clauseless.

* Fill in the infrastructure needed for the last few types of relation scan
paths to support parameterization. We'd have wanted this eventually
anyway, but it is necessary now because a relation that gets pulled up out
of a UNION ALL subquery may acquire a reltargetlist containing lateral
references, meaning that its paths *have* to be parameterized whether or
not we have any code that can push join quals down into the scan.

* Compute data about lateral references early in query_planner(), and save
in RelOptInfo nodes, to avoid repetitive calculations later.

* Assorted corner-case bug fixes.

There's probably still some bugs left, but this is a lot closer to being
real than it was before.

Branch
------
master

Details
-------
http://git.postgresql.org/pg/commitdiff/9ff79b9d4e71822a875c0f5e38f5ec86c7fb079f

Modified Files
--------------
src/backend/nodes/copyfuncs.c | 17 ++
src/backend/nodes/equalfuncs.c | 12 ++
src/backend/nodes/outfuncs.c | 16 ++
src/backend/optimizer/path/allpaths.c | 107 ++++++------
src/backend/optimizer/path/costsize.c | 52 ++++--
src/backend/optimizer/path/indxpath.c | 17 ++-
src/backend/optimizer/path/joinpath.c | 30 ++--
src/backend/optimizer/path/joinrels.c | 86 +++++++++-
src/backend/optimizer/path/tidpath.c | 12 ++-
src/backend/optimizer/plan/analyzejoins.c | 21 +++
src/backend/optimizer/plan/createplan.c | 39 ++++-
src/backend/optimizer/plan/initsplan.c | 267 ++++++++++++++++++++++++++---
src/backend/optimizer/plan/planagg.c | 3 +-
src/backend/optimizer/plan/planmain.c | 9 +
src/backend/optimizer/plan/planner.c | 35 +++-
src/backend/optimizer/prep/prepjointree.c | 8 +-
src/backend/optimizer/prep/prepunion.c | 1 +
src/backend/optimizer/util/pathnode.c | 26 ++-
src/backend/optimizer/util/placeholder.c | 8 +-
src/backend/optimizer/util/relnode.c | 28 ++--
src/backend/optimizer/util/var.c | 1 +
src/backend/rewrite/rewriteManip.c | 3 +
src/include/nodes/nodes.h | 1 +
src/include/nodes/relation.h | 44 +++++-
src/include/optimizer/cost.h | 5 +-
src/include/optimizer/pathnode.h | 8 +-
src/include/optimizer/planmain.h | 2 +
src/include/optimizer/planner.h | 2 +
src/test/regress/expected/join.out | 122 ++++++++++++-
src/test/regress/sql/join.sql | 17 ++
30 files changed, 817 insertions(+), 182 deletions(-)