REINDEX CONCURRENTLY

This adds the CONCURRENTLY option to the REINDEX command.  A REINDEX
CONCURRENTLY on a specific index creates a new index (like CREATE
INDEX CONCURRENTLY), then renames the old index away and the new index
in place and adjusts the dependencies, and then drops the old
index (like DROP INDEX CONCURRENTLY).  The REINDEX command also has
the capability to run its other variants (TABLE, DATABASE) with the
CONCURRENTLY option (but not SYSTEM).

The reindexdb command gets the --concurrently option.

Author: Michael Paquier, Andreas Karlsson, Peter Eisentraut
Reviewed-by: Andres Freund, Fujii Masao, Jim Nasby, Sergei Kornilov
Discussion: https://www.postgresql.org/message-id/flat/60052986-956b-4478-45ed-8bd119e9b9cf%402ndquadrant.com#74948a1044c56c5e817a5050f554ddee

src/include/catalog/dependency.h

@@ -136,6 +136,7 @@ typedef enum ObjectClass
 #define PERFORM_DELETION_QUIETLY			0x0004	/* suppress notices */
 #define PERFORM_DELETION_SKIP_ORIGINAL		0x0008	/* keep original obj */
 #define PERFORM_DELETION_SKIP_EXTENSIONS	0x0010	/* keep extensions */
+#define PERFORM_DELETION_CONCURRENT_LOCK	0x0020	/* normal drop with concurrent lock mode */
 
 
 /* in dependency.c */
@@ -198,6 +199,9 @@ extern long changeDependencyFor(Oid classId, Oid objectId,
 					Oid refClassId, Oid oldRefObjectId,
 					Oid newRefObjectId);
 
+extern long changeDependenciesOn(Oid refClassId, Oid oldRefObjectId,
+								 Oid newRefObjectId);
+
 extern Oid	getExtensionOfObject(Oid classId, Oid objectId);
 
 extern bool sequenceIsOwned(Oid seqId, char deptype, Oid *tableId, int32 *colId);
@@ -208,6 +212,8 @@ extern Oid	get_constraint_index(Oid constraintId);
 
 extern Oid	get_index_constraint(Oid indexId);
 
+extern List *get_index_ref_constraints(Oid indexId);
+
 /* in pg_shdepend.c */
 
 extern void recordSharedDependencyOn(ObjectAddress *depender,

src/include/catalog/index.h

@@ -78,6 +78,20 @@ extern Oid index_create(Relation heapRelation,
 #define	INDEX_CONSTR_CREATE_UPDATE_INDEX	(1 << 3)
 #define	INDEX_CONSTR_CREATE_REMOVE_OLD_DEPS	(1 << 4)
 
+extern Oid index_concurrently_create_copy(Relation heapRelation,
+										  Oid oldIndexId,
+										  const char *newName);
+
+extern void index_concurrently_build(Oid heapRelationId,
+									 Oid indexRelationId);
+
+extern void index_concurrently_swap(Oid newIndexId,
+									Oid oldIndexId,
+									const char *oldName);
+
+extern void index_concurrently_set_dead(Oid heapId,
+										Oid indexId);
+
 extern ObjectAddress index_constraint_create(Relation heapRelation,
 						Oid indexRelationId,
 						Oid parentConstraintId,
@@ -88,7 +102,7 @@ extern ObjectAddress index_constraint_create(Relation heapRelation,
 						bool allow_system_table_mods,
 						bool is_internal);
 
-extern void index_drop(Oid indexId, bool concurrent);
+extern void index_drop(Oid indexId, bool concurrent, bool concurrent_lock_mode);
 
 extern IndexInfo *BuildIndexInfo(Relation index);
 

src/include/commands/defrem.h

@@ -34,10 +34,10 @@ extern ObjectAddress DefineIndex(Oid relationId,
 			bool check_not_in_use,
 			bool skip_build,
 			bool quiet);
-extern void ReindexIndex(RangeVar *indexRelation, int options);
-extern Oid	ReindexTable(RangeVar *relation, int options);
+extern void ReindexIndex(RangeVar *indexRelation, int options, bool concurrent);
+extern Oid	ReindexTable(RangeVar *relation, int options, bool concurrent);
 extern void ReindexMultipleTables(const char *objectName, ReindexObjectType objectKind,
-					  int options);
+					  int options, bool concurrent);
 extern char *makeObjectName(const char *name1, const char *name2,
 			   const char *label);
 extern char *ChooseRelationName(const char *name1, const char *name2,

src/include/nodes/parsenodes.h

@@ -3305,6 +3305,7 @@ typedef struct ReindexStmt
 	RangeVar   *relation;		/* Table or index to reindex */
 	const char *name;			/* name of database to reindex */
 	int			options;		/* Reindex options flags */
+	bool		concurrent;		/* reindex concurrently? */
 } ReindexStmt;
 
 /* ----------------------