pgstat: rename pgstat_initstats() to pgstat_relation_init().

The old name was overly generic. An upcoming commit moves relation stats
handling into its own file, making pgstat_initstats() look even more out of
place.

Author: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/20220303021600.hs34ghqcw6zcokdh@alap3.anarazel.de

Author: anarazel

src/backend/access/common/relation.c

@@ -73,7 +73,7 @@ relation_open(Oid relationId, LOCKMODE lockmode)
 	if (RelationUsesLocalBuffers(r))
 		MyXactFlags |= XACT_FLAGS_ACCESSEDTEMPNAMESPACE;
 
-	pgstat_initstats(r);
+	pgstat_relation_init(r);
 
 	return r;
 }
@@ -123,7 +123,7 @@ try_relation_open(Oid relationId, LOCKMODE lockmode)
 	if (RelationUsesLocalBuffers(r))
 		MyXactFlags |= XACT_FLAGS_ACCESSEDTEMPNAMESPACE;
 
-	pgstat_initstats(r);
+	pgstat_relation_init(r);
 
 	return r;
 }

src/backend/postmaster/pgstat.c

@@ -188,7 +188,7 @@ static bool pgStatRunningInCollector = false;
  * for the life of the backend.  Also, we zero out the t_id fields of the
  * contained PgStat_TableStatus structs whenever they are not actively in use.
  * This allows relcache pgstat_info pointers to be treated as long-lived data,
- * avoiding repeated searches in pgstat_initstats() when a relation is
+ * avoiding repeated searches in pgstat_relation_init() when a relation is
  * repeatedly opened during a transaction.
  */
 #define TABSTAT_QUANTUM		100 /* we alloc this many at a time */
@@ -2147,7 +2147,7 @@ pgstat_end_function_usage(PgStat_FunctionCallUsage *fcu, bool finalize)
 
 
 /* ----------
- * pgstat_initstats() -
+ * pgstat_relation_init() -
  *
  *	Initialize a relcache entry to count access statistics.
  *	Called whenever a relation is opened.
@@ -2159,7 +2159,7 @@ pgstat_end_function_usage(PgStat_FunctionCallUsage *fcu, bool finalize)
  * ----------
  */
 void
-pgstat_initstats(Relation rel)
+pgstat_relation_init(Relation rel)
 {
 	Oid			rel_id = rel->rd_id;
 	char		relkind = rel->rd_rel->relkind;

src/include/pgstat.h

@@ -1102,7 +1102,7 @@ extern void pgstat_initialize(void);
 extern PgStat_TableStatus *find_tabstat_entry(Oid rel_id);
 extern PgStat_BackendFunctionEntry *find_funcstat_entry(Oid func_id);
 
-extern void pgstat_initstats(Relation rel);
+extern void pgstat_relation_init(Relation rel);
 
 #define pgstat_relation_should_count(rel)                           \
 	(likely((rel)->pgstat_info != NULL))