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

1 files changed, 175 insertions, 0 deletions

diff --git a/src/include/optimizer/optimizer.h b/src/include/optimizer/optimizer.h
new file mode 100644
index 00000000000..1cd5c80e768
--- /dev/null
+++ b/src/include/optimizer/optimizer.h
@@ -0,0 +1,175 @@
+/*-------------------------------------------------------------------------
+ *
+ * optimizer.h
+ *	  External API for the Postgres planner.
+ *
+ * This header is meant to define everything that the core planner
+ * exposes for use by non-planner modules.
+ *
+ * Note that there are files outside src/backend/optimizer/ that are
+ * considered planner modules, because they're too much in bed with
+ * planner operations to be treated otherwise.  FDW planning code is an
+ * example.  For the most part, however, code outside the core planner
+ * should not need to include any optimizer/ header except this one.
+ *
+ * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/optimizer/optimizer.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef OPTIMIZER_H
+#define OPTIMIZER_H
+
+#include "nodes/parsenodes.h"
+
+/*
+ * We don't want to include nodes/relation.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.
+ */
+#ifndef HAVE_PLANNERINFO_TYPEDEF
+typedef struct PlannerInfo PlannerInfo;
+#define HAVE_PLANNERINFO_TYPEDEF 1
+#endif
+
+/* Likewise for SpecialJoinInfo. */
+#ifndef HAVE_SPECIALJOININFO_TYPEDEF
+typedef struct SpecialJoinInfo SpecialJoinInfo;
+#define HAVE_SPECIALJOININFO_TYPEDEF 1
+#endif
+
+/* It also seems best not to include plannodes.h, params.h, or htup.h here */
+struct PlannedStmt;
+struct ParamListInfoData;
+struct HeapTupleData;
+
+
+/* in path/clausesel.c: */
+
+extern Selectivity clause_selectivity(PlannerInfo *root,
+				   Node *clause,
+				   int varRelid,
+				   JoinType jointype,
+				   SpecialJoinInfo *sjinfo);
+extern Selectivity clauselist_selectivity(PlannerInfo *root,
+					   List *clauses,
+					   int varRelid,
+					   JoinType jointype,
+					   SpecialJoinInfo *sjinfo);
+
+/* in path/costsize.c: */
+
+/* widely used cost parameters */
+extern PGDLLIMPORT double seq_page_cost;
+extern PGDLLIMPORT double random_page_cost;
+extern PGDLLIMPORT double cpu_tuple_cost;
+extern PGDLLIMPORT double cpu_index_tuple_cost;
+extern PGDLLIMPORT double cpu_operator_cost;
+extern PGDLLIMPORT double parallel_tuple_cost;
+extern PGDLLIMPORT double parallel_setup_cost;
+extern PGDLLIMPORT int effective_cache_size;
+
+extern double clamp_row_est(double nrows);
+
+/* in plan/planner.c: */
+
+/* possible values for force_parallel_mode */
+typedef enum
+{
+	FORCE_PARALLEL_OFF,
+	FORCE_PARALLEL_ON,
+	FORCE_PARALLEL_REGRESS
+}			ForceParallelMode;
+
+/* GUC parameters */
+extern int	force_parallel_mode;
+extern bool parallel_leader_participation;
+
+extern struct PlannedStmt *planner(Query *parse, int cursorOptions,
+		struct ParamListInfoData *boundParams);
+
+extern Expr *expression_planner(Expr *expr);
+extern Expr *expression_planner_with_deps(Expr *expr,
+							 List **relationOids,
+							 List **invalItems);
+
+extern bool plan_cluster_use_sort(Oid tableOid, Oid indexOid);
+extern int	plan_create_index_workers(Oid tableOid, Oid indexOid);
+
+/* in plan/setrefs.c: */
+
+extern void extract_query_dependencies(Node *query,
+						   List **relationOids,
+						   List **invalItems,
+						   bool *hasRowSecurity);
+
+/* in prep/prepqual.c: */
+
+extern Node *negate_clause(Node *node);
+extern Expr *canonicalize_qual(Expr *qual, bool is_check);
+
+/* in util/clauses.c: */
+
+extern bool contain_mutable_functions(Node *clause);
+extern bool contain_volatile_functions(Node *clause);
+extern bool contain_volatile_functions_not_nextval(Node *clause);
+
+extern Node *eval_const_expressions(PlannerInfo *root, Node *node);
+
+extern Node *estimate_expression_value(PlannerInfo *root, Node *node);
+
+extern Expr *evaluate_expr(Expr *expr, Oid result_type, int32 result_typmod,
+			  Oid result_collation);
+
+extern List *expand_function_arguments(List *args, Oid result_type,
+						  struct HeapTupleData *func_tuple);
+
+/* in util/predtest.c: */
+
+extern bool predicate_implied_by(List *predicate_list, List *clause_list,
+					 bool weak);
+extern bool predicate_refuted_by(List *predicate_list, List *clause_list,
+					 bool weak);
+
+/* in util/tlist.c: */
+
+extern int	count_nonjunk_tlist_entries(List *tlist);
+extern TargetEntry *get_sortgroupref_tle(Index sortref,
+					 List *targetList);
+extern TargetEntry *get_sortgroupclause_tle(SortGroupClause *sgClause,
+						List *targetList);
+extern Node *get_sortgroupclause_expr(SortGroupClause *sgClause,
+						 List *targetList);
+extern List *get_sortgrouplist_exprs(List *sgClauses,
+						List *targetList);
+extern SortGroupClause *get_sortgroupref_clause(Index sortref,
+						List *clauses);
+extern SortGroupClause *get_sortgroupref_clause_noerr(Index sortref,
+							  List *clauses);
+
+/* in util/var.c: */
+
+/* Bits that can be OR'd into the flags argument of pull_var_clause() */
+#define PVC_INCLUDE_AGGREGATES	0x0001	/* include Aggrefs in output list */
+#define PVC_RECURSE_AGGREGATES	0x0002	/* recurse into Aggref arguments */
+#define PVC_INCLUDE_WINDOWFUNCS 0x0004	/* include WindowFuncs in output list */
+#define PVC_RECURSE_WINDOWFUNCS 0x0008	/* recurse into WindowFunc arguments */
+#define PVC_INCLUDE_PLACEHOLDERS	0x0010	/* include PlaceHolderVars in
+											 * output list */
+#define PVC_RECURSE_PLACEHOLDERS	0x0020	/* recurse into PlaceHolderVar
+											 * arguments */
+
+extern Bitmapset *pull_varnos(Node *node);
+extern Bitmapset *pull_varnos_of_level(Node *node, int levelsup);
+extern void pull_varattnos(Node *node, Index varno, Bitmapset **varattnos);
+extern List *pull_vars_of_level(Node *node, int levelsup);
+extern bool contain_var_clause(Node *node);
+extern bool contain_vars_of_level(Node *node, int levelsup);
+extern int	locate_var_of_level(Node *node, int levelsup);
+extern List *pull_var_clause(Node *node, int flags);
+extern Node *flatten_join_alias_vars(Query *query, Node *node);
+
+#endif							/* OPTIMIZER_H */