Add temporal PRIMARY KEY and UNIQUE constraints

Add WITHOUT OVERLAPS clause to PRIMARY KEY and UNIQUE constraints.
These are backed by GiST indexes instead of B-tree indexes, since they
are essentially exclusion constraints with = for the scalar parts of
the key and && for the temporal part.

Author: Paul A. Jungwirth <pj@illuminatedcomputing.com>
Reviewed-by: Peter Eisentraut <peter@eisentraut.org>
Reviewed-by: jian he <jian.universality@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/CA+renyUApHgSZF9-nd-a0+OPGharLQLO=mDHcY4_qQ0+noCUVg@mail.gmail.com

src/include/access/gist.h

@@ -17,6 +17,7 @@
 #define GIST_H
 
 #include "access/itup.h"
+#include "access/stratnum.h"
 #include "access/transam.h"
 #include "access/xlog.h"
 #include "access/xlogdefs.h"
@@ -246,4 +247,6 @@ typedef struct
 	do { (e).key = (k); (e).rel = (r); (e).page = (pg); \
 		 (e).offset = (o); (e).leafkey = (l); } while (0)
 
+extern StrategyNumber GistTranslateStratnum(Oid opclass, StrategyNumber strat);
+
 #endif							/* GIST_H */

src/include/catalog/catversion.h

@@ -57,6 +57,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	202401201
+#define CATALOG_VERSION_NO	202401241
 
 #endif

src/include/catalog/index.h

@@ -92,6 +92,7 @@ extern Oid	index_create(Relation heapRelation,
 #define	INDEX_CONSTR_CREATE_INIT_DEFERRED	(1 << 2)
 #define	INDEX_CONSTR_CREATE_UPDATE_INDEX	(1 << 3)
 #define	INDEX_CONSTR_CREATE_REMOVE_OLD_DEPS	(1 << 4)
+#define	INDEX_CONSTR_CREATE_WITHOUT_OVERLAPS (1 << 5)
 
 extern Oid	index_concurrently_create_copy(Relation heapRelation,
 										   Oid oldIndexId,

src/include/catalog/pg_constraint.h

@@ -107,6 +107,12 @@ CATALOG(pg_constraint,2606,ConstraintRelationId)
 	/* Has a local definition and cannot be inherited */
 	bool		connoinherit;
 
+	/*
+	 * For primary keys and unique constraints, signifies the last column uses
+	 * overlaps instead of equals.
+	 */
+	bool		conwithoutoverlaps;
+
 #ifdef CATALOG_VARLEN			/* variable-length fields start here */
 
 	/*
@@ -146,7 +152,8 @@ CATALOG(pg_constraint,2606,ConstraintRelationId)
 
 	/*
 	 * If an exclusion constraint, the OIDs of the exclusion operators for
-	 * each column of the constraint
+	 * each column of the constraint.  Also set for unique constraints/primary
+	 * keys using WITHOUT OVERLAPS.
 	 */
 	Oid			conexclop[1] BKI_LOOKUP(pg_operator);
 
@@ -238,6 +245,7 @@ extern Oid	CreateConstraintEntry(const char *constraintName,
 								  bool conIsLocal,
 								  int conInhCount,
 								  bool conNoInherit,
+								  bool conWithoutOverlaps,
 								  bool is_internal);
 
 extern bool ConstraintNameIsUsed(ConstraintCategory conCat, Oid objId,

src/include/commands/defrem.h

@@ -14,6 +14,7 @@
 #ifndef DEFREM_H
 #define DEFREM_H
 
+#include "access/stratnum.h"
 #include "catalog/objectaddress.h"
 #include "nodes/params.h"
 #include "parser/parse_node.h"
@@ -44,10 +45,13 @@ extern char *ChooseRelationName(const char *name1, const char *name2,
 extern bool CheckIndexCompatible(Oid oldId,
 								 const char *accessMethodName,
 								 const List *attributeList,
-								 const List *exclusionOpNames);
+								 const List *exclusionOpNames,
+								 bool isWithoutOverlaps);
 extern Oid	GetDefaultOpClass(Oid type_id, Oid am_id);
 extern Oid	ResolveOpClass(const List *opclass, Oid attrType,
 						   const char *accessMethodName, Oid accessMethodId);
+extern void GetOperatorFromWellKnownStrategy(Oid opclass, Oid atttype,
+											 Oid *opid, StrategyNumber *strat);
 
 /* commands/functioncmds.c */
 extern ObjectAddress CreateFunction(ParseState *pstate, CreateFunctionStmt *stmt);

src/include/nodes/parsenodes.h

@@ -2590,6 +2590,7 @@ typedef struct Constraint
 	bool		nulls_not_distinct; /* null treatment for UNIQUE constraints */
 	List	   *keys;			/* String nodes naming referenced key
 								 * column(s); also used for NOT NULL */
+	bool		without_overlaps;	/* WITHOUT OVERLAPS specified */
 	List	   *including;		/* String nodes naming referenced nonkey
 								 * column(s) */
 
@@ -3219,6 +3220,7 @@ typedef struct IndexStmt
 	bool		nulls_not_distinct; /* null treatment for UNIQUE constraints */
 	bool		primary;		/* is index a primary key? */
 	bool		isconstraint;	/* is it for a pkey/unique constraint? */
+	bool		iswithoutoverlaps;	/* is the constraint WITHOUT OVERLAPS? */
 	bool		deferrable;		/* is the constraint DEFERRABLE? */
 	bool		initdeferred;	/* is the constraint INITIALLY DEFERRED? */
 	bool		transformed;	/* true when transformIndexStmt is finished */