Rename nodes/relation.h to nodes/pathnodes.h.

The old name of this file was never a very good indication of what it
was for.  Now that there's also access/relation.h, we have a potential
confusion hazard as well, so let's rename it to something more apropos.
Per discussion, "pathnodes.h" is reasonable, since a good fraction of
the file is Path node definitions.

While at it, tweak a couple of other headers that were gratuitously
importing relation.h into modules that don't need it.

Discussion: https://postgr.es/m/7719.1548688728@sss.pgh.pa.us

src/include/optimizer/appendinfo.h

@@ -14,7 +14,7 @@
 #ifndef APPENDINFO_H
 #define APPENDINFO_H
 
-#include "nodes/relation.h"
+#include "nodes/pathnodes.h"
 #include "utils/relcache.h"
 
 extern AppendRelInfo *make_append_rel_info(Relation parentrel,

src/include/optimizer/clauses.h

@@ -15,7 +15,7 @@
 #define CLAUSES_H
 
 #include "access/htup.h"
-#include "nodes/relation.h"
+#include "nodes/pathnodes.h"
 
 typedef struct
 {

src/include/optimizer/cost.h

@@ -14,8 +14,8 @@
 #ifndef COST_H
 #define COST_H
 
+#include "nodes/pathnodes.h"
 #include "nodes/plannodes.h"
-#include "nodes/relation.h"
 
 
 /* defaults for costsize.c's Cost parameters */

src/include/optimizer/geqo.h

@@ -22,7 +22,7 @@
 #ifndef GEQO_H
 #define GEQO_H
 
-#include "nodes/relation.h"
+#include "nodes/pathnodes.h"
 #include "optimizer/geqo_gene.h"
 
 

src/include/optimizer/inherit.h

@@ -14,7 +14,7 @@
 #ifndef INHERIT_H
 #define INHERIT_H
 
-#include "nodes/relation.h"
+#include "nodes/pathnodes.h"
 
 
 extern void expand_inherited_tables(PlannerInfo *root);

src/include/optimizer/joininfo.h

@@ -14,7 +14,7 @@
 #ifndef JOININFO_H
 #define JOININFO_H
 
-#include "nodes/relation.h"
+#include "nodes/pathnodes.h"
 
 
 extern bool have_relevant_joinclause(PlannerInfo *root,

src/include/optimizer/optimizer.h

@@ -25,10 +25,10 @@
 #include "nodes/parsenodes.h"
 
 /*
- * We don't want to include nodes/relation.h here, because non-planner
+ * We don't want to include nodes/pathnodes.h here, because non-planner
  * code should generally treat PlannerInfo as an opaque typedef.
  * But we'd like such code to use that typedef name, so define the
- * typedef either here or in relation.h, whichever is read first.
+ * typedef either here or in pathnodes.h, whichever is read first.
  */
 #ifndef HAVE_PLANNERINFO_TYPEDEF
 typedef struct PlannerInfo PlannerInfo;

src/include/optimizer/orclauses.h

@@ -14,7 +14,7 @@
 #ifndef ORCLAUSES_H
 #define ORCLAUSES_H
 
-#include "nodes/relation.h"
+#include "nodes/pathnodes.h"
 
 extern void extract_restriction_or_clauses(PlannerInfo *root);
 

src/include/optimizer/paramassign.h

@@ -13,7 +13,7 @@
 #ifndef PARAMASSIGN_H
 #define PARAMASSIGN_H
 
-#include "nodes/relation.h"
+#include "nodes/pathnodes.h"
 
 extern Param *replace_outer_var(PlannerInfo *root, Var *var);
 extern Param *replace_outer_placeholdervar(PlannerInfo *root,

src/include/optimizer/pathnode.h

@@ -15,7 +15,7 @@
 #define PATHNODE_H
 
 #include "nodes/bitmapset.h"
-#include "nodes/relation.h"
+#include "nodes/pathnodes.h"
 
 
 /*

src/include/optimizer/paths.h

@@ -14,7 +14,7 @@
 #ifndef PATHS_H
 #define PATHS_H
 
-#include "nodes/relation.h"
+#include "nodes/pathnodes.h"
 
 
 /*

src/include/optimizer/placeholder.h

@@ -14,7 +14,7 @@
 #ifndef PLACEHOLDER_H
 #define PLACEHOLDER_H
 
-#include "nodes/relation.h"
+#include "nodes/pathnodes.h"
 
 
 extern PlaceHolderVar *make_placeholder_expr(PlannerInfo *root, Expr *expr,

src/include/optimizer/plancat.h

@@ -14,7 +14,7 @@
 #ifndef PLANCAT_H
 #define PLANCAT_H
 
-#include "nodes/relation.h"
+#include "nodes/pathnodes.h"
 #include "utils/relcache.h"
 
 /* Hook for plugins to get control in get_relation_info() */

src/include/optimizer/planmain.h

@@ -14,8 +14,8 @@
 #ifndef PLANMAIN_H
 #define PLANMAIN_H
 
+#include "nodes/pathnodes.h"
 #include "nodes/plannodes.h"
-#include "nodes/relation.h"
 
 /* GUC parameters */
 #define DEFAULT_CURSOR_TUPLE_FRACTION 0.1

src/include/optimizer/planner.h

@@ -18,8 +18,8 @@
 #ifndef PLANNER_H
 #define PLANNER_H
 
+#include "nodes/pathnodes.h"
 #include "nodes/plannodes.h"
-#include "nodes/relation.h"
 
 
 /* Hook for plugins to get control in planner() */

src/include/optimizer/prep.h

@@ -14,8 +14,8 @@
 #ifndef PREP_H
 #define PREP_H
 
+#include "nodes/pathnodes.h"
 #include "nodes/plannodes.h"
-#include "nodes/relation.h"
 
 
 /*

src/include/optimizer/restrictinfo.h

@@ -14,7 +14,7 @@
 #ifndef RESTRICTINFO_H
 #define RESTRICTINFO_H
 
-#include "nodes/relation.h"
+#include "nodes/pathnodes.h"
 
 
 /* Convenience macro for the common case of a valid-everywhere qual */

src/include/optimizer/subselect.h

@@ -13,8 +13,8 @@
 #ifndef SUBSELECT_H
 #define SUBSELECT_H
 
+#include "nodes/pathnodes.h"
 #include "nodes/plannodes.h"
-#include "nodes/relation.h"
 
 extern void SS_process_ctes(PlannerInfo *root);
 extern JoinExpr *convert_ANY_sublink_to_join(PlannerInfo *root,

src/include/optimizer/tlist.h

@@ -14,7 +14,7 @@
 #ifndef TLIST_H
 #define TLIST_H
 
-#include "nodes/relation.h"
+#include "nodes/pathnodes.h"
 
 
 extern TargetEntry *tlist_member(Expr *node, List *targetlist);