Refactor planner's header files.

Create a new header optimizer/optimizer.h, which exposes just the
planner functions that can be used "at arm's length", without need
to access Paths or the other planner-internal data structures defined
in nodes/relation.h.  This is intended to provide the whole planner
API seen by most of the rest of the system; although FDWs still need
to use additional stuff, and more thought is also needed about just
what selfuncs.c should rely on.

The main point of doing this now is to limit the amount of new
#include baggage that will be needed by "planner support functions",
which I expect to introduce later, and which will be in relevant
datatype modules rather than anywhere near the planner.

This commit just moves relevant declarations into optimizer.h from
other header files (a couple of which go away because everything
got moved), and adjusts #include lists to match.  There's further
cleanup that could be done if we want to decide that some stuff
being exposed by optimizer.h doesn't belong in the planner at all,
but I'll leave that for another day.

Discussion: https://postgr.es/m/11460.1548706639@sss.pgh.pa.us

src/backend/optimizer/path/allpaths.c

@@ -35,13 +35,13 @@
 #include "optimizer/cost.h"
 #include "optimizer/geqo.h"
 #include "optimizer/inherit.h"
+#include "optimizer/optimizer.h"
 #include "optimizer/pathnode.h"
 #include "optimizer/paths.h"
 #include "optimizer/plancat.h"
 #include "optimizer/planner.h"
 #include "optimizer/restrictinfo.h"
 #include "optimizer/tlist.h"
-#include "optimizer/var.h"
 #include "parser/parse_clause.h"
 #include "parser/parsetree.h"
 #include "partitioning/partprune.h"

src/backend/optimizer/path/clausesel.c

@@ -18,6 +18,7 @@
 #include "nodes/nodeFuncs.h"
 #include "optimizer/clauses.h"
 #include "optimizer/cost.h"
+#include "optimizer/optimizer.h"
 #include "optimizer/pathnode.h"
 #include "optimizer/plancat.h"
 #include "utils/fmgroids.h"

src/backend/optimizer/path/costsize.c

@@ -83,6 +83,7 @@
 #include "nodes/nodeFuncs.h"
 #include "optimizer/clauses.h"
 #include "optimizer/cost.h"
+#include "optimizer/optimizer.h"
 #include "optimizer/pathnode.h"
 #include "optimizer/paths.h"
 #include "optimizer/placeholder.h"

src/backend/optimizer/path/equivclass.c

@@ -24,11 +24,11 @@
 #include "nodes/nodeFuncs.h"
 #include "optimizer/appendinfo.h"
 #include "optimizer/clauses.h"
+#include "optimizer/optimizer.h"
 #include "optimizer/pathnode.h"
 #include "optimizer/paths.h"
 #include "optimizer/planmain.h"
 #include "optimizer/restrictinfo.h"
-#include "optimizer/var.h"
 #include "utils/lsyscache.h"
 
 

src/backend/optimizer/path/indxpath.c

@@ -28,12 +28,11 @@
 #include "nodes/nodeFuncs.h"
 #include "optimizer/clauses.h"
 #include "optimizer/cost.h"
+#include "optimizer/optimizer.h"
 #include "optimizer/pathnode.h"
 #include "optimizer/paths.h"
-#include "optimizer/predtest.h"
 #include "optimizer/prep.h"
 #include "optimizer/restrictinfo.h"
-#include "optimizer/var.h"
 #include "utils/builtins.h"
 #include "utils/bytea.h"
 #include "utils/lsyscache.h"

src/backend/optimizer/path/pathkeys.c

@@ -21,10 +21,9 @@
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/plannodes.h"
-#include "optimizer/clauses.h"
+#include "optimizer/optimizer.h"
 #include "optimizer/pathnode.h"
 #include "optimizer/paths.h"
-#include "optimizer/tlist.h"
 #include "utils/lsyscache.h"
 
 

src/backend/optimizer/path/tidpath.c

@@ -40,10 +40,10 @@
 #include "catalog/pg_type.h"
 #include "nodes/nodeFuncs.h"
 #include "optimizer/clauses.h"
+#include "optimizer/optimizer.h"
 #include "optimizer/pathnode.h"
 #include "optimizer/paths.h"
 #include "optimizer/restrictinfo.h"
-#include "optimizer/var.h"
 
 
 /*

src/backend/optimizer/plan/analyzejoins.c

@@ -25,11 +25,11 @@
 #include "nodes/nodeFuncs.h"
 #include "optimizer/clauses.h"
 #include "optimizer/joininfo.h"
+#include "optimizer/optimizer.h"
 #include "optimizer/pathnode.h"
 #include "optimizer/paths.h"
 #include "optimizer/planmain.h"
 #include "optimizer/tlist.h"
-#include "optimizer/var.h"
 #include "utils/lsyscache.h"
 
 /* local functions */

src/backend/optimizer/plan/createplan.c

@@ -28,16 +28,15 @@
 #include "nodes/nodeFuncs.h"
 #include "optimizer/clauses.h"
 #include "optimizer/cost.h"
+#include "optimizer/optimizer.h"
 #include "optimizer/paramassign.h"
 #include "optimizer/paths.h"
 #include "optimizer/placeholder.h"
 #include "optimizer/plancat.h"
 #include "optimizer/planmain.h"
-#include "optimizer/predtest.h"
 #include "optimizer/restrictinfo.h"
 #include "optimizer/subselect.h"
 #include "optimizer/tlist.h"
-#include "optimizer/var.h"
 #include "parser/parse_clause.h"
 #include "parser/parsetree.h"
 #include "partitioning/partprune.h"

src/backend/optimizer/plan/initsplan.c

@@ -21,6 +21,7 @@
 #include "optimizer/clauses.h"
 #include "optimizer/cost.h"
 #include "optimizer/joininfo.h"
+#include "optimizer/optimizer.h"
 #include "optimizer/pathnode.h"
 #include "optimizer/paths.h"
 #include "optimizer/placeholder.h"
@@ -28,7 +29,6 @@
 #include "optimizer/planner.h"
 #include "optimizer/prep.h"
 #include "optimizer/restrictinfo.h"
-#include "optimizer/var.h"
 #include "parser/analyze.h"
 #include "rewrite/rewriteManip.h"
 #include "utils/lsyscache.h"

src/backend/optimizer/plan/planagg.c

@@ -35,6 +35,7 @@
 #include "nodes/nodeFuncs.h"
 #include "optimizer/clauses.h"
 #include "optimizer/cost.h"
+#include "optimizer/optimizer.h"
 #include "optimizer/pathnode.h"
 #include "optimizer/paths.h"
 #include "optimizer/planmain.h"

src/backend/optimizer/plan/planmain.c

@@ -23,6 +23,7 @@
 #include "optimizer/appendinfo.h"
 #include "optimizer/clauses.h"
 #include "optimizer/inherit.h"
+#include "optimizer/optimizer.h"
 #include "optimizer/orclauses.h"
 #include "optimizer/pathnode.h"
 #include "optimizer/paths.h"

src/backend/optimizer/plan/planner.c

@@ -43,6 +43,7 @@
 #include "optimizer/clauses.h"
 #include "optimizer/cost.h"
 #include "optimizer/inherit.h"
+#include "optimizer/optimizer.h"
 #include "optimizer/paramassign.h"
 #include "optimizer/pathnode.h"
 #include "optimizer/paths.h"
@@ -52,7 +53,6 @@
 #include "optimizer/prep.h"
 #include "optimizer/subselect.h"
 #include "optimizer/tlist.h"
-#include "optimizer/var.h"
 #include "parser/analyze.h"
 #include "parser/parsetree.h"
 #include "parser/parse_agg.h"

src/backend/optimizer/plan/setrefs.c

@@ -19,6 +19,7 @@
 #include "catalog/pg_type.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
+#include "optimizer/optimizer.h"
 #include "optimizer/pathnode.h"
 #include "optimizer/planmain.h"
 #include "optimizer/planner.h"

src/backend/optimizer/plan/subselect.c

@@ -25,13 +25,13 @@
 #include "nodes/nodeFuncs.h"
 #include "optimizer/clauses.h"
 #include "optimizer/cost.h"
+#include "optimizer/optimizer.h"
 #include "optimizer/paramassign.h"
 #include "optimizer/pathnode.h"
 #include "optimizer/planmain.h"
 #include "optimizer/planner.h"
 #include "optimizer/prep.h"
 #include "optimizer/subselect.h"
-#include "optimizer/var.h"
 #include "parser/parse_relation.h"
 #include "rewrite/rewriteManip.h"
 #include "utils/builtins.h"

src/backend/optimizer/prep/prepjointree.c

@@ -29,11 +29,11 @@
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "optimizer/clauses.h"
+#include "optimizer/optimizer.h"
 #include "optimizer/placeholder.h"
 #include "optimizer/prep.h"
 #include "optimizer/subselect.h"
 #include "optimizer/tlist.h"
-#include "optimizer/var.h"
 #include "parser/parse_relation.h"
 #include "parser/parsetree.h"
 #include "rewrite/rewriteManip.h"

src/backend/optimizer/prep/prepqual.c

@@ -33,7 +33,7 @@
 
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
-#include "optimizer/clauses.h"
+#include "optimizer/optimizer.h"
 #include "optimizer/prep.h"
 #include "utils/lsyscache.h"
 

src/backend/optimizer/prep/preptlist.c

@@ -44,9 +44,9 @@
 #include "access/table.h"
 #include "catalog/pg_type.h"
 #include "nodes/makefuncs.h"
+#include "optimizer/optimizer.h"
 #include "optimizer/prep.h"
 #include "optimizer/tlist.h"
-#include "optimizer/var.h"
 #include "parser/parsetree.h"
 #include "parser/parse_coerce.h"
 #include "rewrite/rewriteHandler.h"

src/backend/optimizer/util/clauses.c

@@ -34,9 +34,9 @@
 #include "nodes/nodeFuncs.h"
 #include "optimizer/clauses.h"
 #include "optimizer/cost.h"
+#include "optimizer/optimizer.h"
 #include "optimizer/planmain.h"
 #include "optimizer/prep.h"
-#include "optimizer/var.h"
 #include "parser/analyze.h"
 #include "parser/parse_agg.h"
 #include "parser/parse_coerce.h"

src/backend/optimizer/util/orclauses.c

@@ -19,6 +19,7 @@
 #include "nodes/nodeFuncs.h"
 #include "optimizer/clauses.h"
 #include "optimizer/cost.h"
+#include "optimizer/optimizer.h"
 #include "optimizer/orclauses.h"
 #include "optimizer/restrictinfo.h"
 

src/backend/optimizer/util/pathnode.c

@@ -23,13 +23,13 @@
 #include "optimizer/appendinfo.h"
 #include "optimizer/clauses.h"
 #include "optimizer/cost.h"
+#include "optimizer/optimizer.h"
 #include "optimizer/pathnode.h"
 #include "optimizer/paths.h"
 #include "optimizer/planmain.h"
 #include "optimizer/prep.h"
 #include "optimizer/restrictinfo.h"
 #include "optimizer/tlist.h"
-#include "optimizer/var.h"
 #include "parser/parsetree.h"
 #include "utils/lsyscache.h"
 #include "utils/memutils.h"

src/backend/optimizer/util/placeholder.c

@@ -17,10 +17,10 @@
 
 #include "nodes/nodeFuncs.h"
 #include "optimizer/cost.h"
+#include "optimizer/optimizer.h"
 #include "optimizer/pathnode.h"
 #include "optimizer/placeholder.h"
 #include "optimizer/planmain.h"
-#include "optimizer/var.h"
 #include "utils/lsyscache.h"
 
 /* Local functions */

src/backend/optimizer/util/plancat.c

@@ -35,8 +35,8 @@
 #include "nodes/makefuncs.h"
 #include "optimizer/clauses.h"
 #include "optimizer/cost.h"
+#include "optimizer/optimizer.h"
 #include "optimizer/plancat.h"
-#include "optimizer/predtest.h"
 #include "optimizer/prep.h"
 #include "partitioning/partbounds.h"
 #include "parser/parse_relation.h"

src/backend/optimizer/util/predtest.c

@@ -21,8 +21,8 @@
 #include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
-#include "optimizer/clauses.h"
-#include "optimizer/predtest.h"
+#include "nodes/relation.h"
+#include "optimizer/optimizer.h"
 #include "utils/array.h"
 #include "utils/inval.h"
 #include "utils/lsyscache.h"

src/backend/optimizer/util/restrictinfo.c

@@ -17,8 +17,8 @@
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "optimizer/clauses.h"
+#include "optimizer/optimizer.h"
 #include "optimizer/restrictinfo.h"
-#include "optimizer/var.h"
 
 
 static RestrictInfo *make_restrictinfo_internal(Expr *clause,

src/backend/optimizer/util/tlist.c

@@ -17,6 +17,7 @@
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #include "optimizer/cost.h"
+#include "optimizer/optimizer.h"
 #include "optimizer/tlist.h"
 
 

src/backend/optimizer/util/var.c

@@ -22,8 +22,8 @@
 
 #include "access/sysattr.h"
 #include "nodes/nodeFuncs.h"
+#include "optimizer/optimizer.h"
 #include "optimizer/prep.h"
-#include "optimizer/var.h"
 #include "parser/parsetree.h"
 #include "rewrite/rewriteManip.h"