Avoid including commands/dbcommands.h in so many places

This has been done historically because of get_database_name (which
since commit cb98e6fb8fd4 belongs in lsyscache.c/h, so let's move it
there) and get_database_oid (which is in the right place, but whose
declaration should appear in pg_database.h rather than dbcommands.h).
Clean this up.

Also, xlogreader.h and stringinfo.h are no longer needed by dbcommands.h
since commit f1fd515b393a, so remove them.

Author: Álvaro Herrera <alvherre@kurilemu.de>
Reviewed-by: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Discussion: https://postgr.es/m/202508191031.5ipojyuaswzt@alvherre.pgsql

1 files changed, 27 insertions, 0 deletions

diff --git a/src/backend/utils/cache/lsyscache.c b/src/backend/utils/cache/lsyscache.c
index 032bb6222c4..fa7cd7e06a7 100644
--- a/src/backend/utils/cache/lsyscache.c
+++ b/src/backend/utils/cache/lsyscache.c
@@ -26,6 +26,7 @@
 #include "catalog/pg_class.h"
 #include "catalog/pg_collation.h"
 #include "catalog/pg_constraint.h"
+#include "catalog/pg_database.h"
 #include "catalog/pg_index.h"
 #include "catalog/pg_language.h"
 #include "catalog/pg_namespace.h"
@@ -1247,6 +1248,32 @@ get_constraint_type(Oid conoid)
 	return contype;
 }
 
+/*				---------- DATABASE CACHE ----------					 */
+
+/*
+ * get_database_name - given a database OID, look up the name
+ *
+ * Returns a palloc'd string, or NULL if no such database.
+ */
+char *
+get_database_name(Oid dbid)
+{
+	HeapTuple	dbtuple;
+	char	   *result;
+
+	dbtuple = SearchSysCache1(DATABASEOID, ObjectIdGetDatum(dbid));
+	if (HeapTupleIsValid(dbtuple))
+	{
+		result = pstrdup(NameStr(((Form_pg_database) GETSTRUCT(dbtuple))->datname));
+		ReleaseSysCache(dbtuple);
+	}
+	else
+		result = NULL;
+
+	return result;
+}
+
+
 /*				---------- LANGUAGE CACHE ----------					 */
 
 char *