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

6 files changed, 29 insertions, 5 deletions

diff --git a/src/backend/utils/adt/acl.c b/src/backend/utils/adt/acl.c
index 1213f9106d5..7dadaefdfc1 100644
--- a/src/backend/utils/adt/acl.c
+++ b/src/backend/utils/adt/acl.c
@@ -31,7 +31,6 @@
 #include "catalog/pg_proc.h"
 #include "catalog/pg_tablespace.h"
 #include "catalog/pg_type.h"
-#include "commands/dbcommands.h"
 #include "commands/proclang.h"
 #include "commands/tablespace.h"
 #include "common/hashfn.h"
diff --git a/src/backend/utils/adt/dbsize.c b/src/backend/utils/adt/dbsize.c
index 3a059f4ace0..894d226541f 100644
--- a/src/backend/utils/adt/dbsize.c
+++ b/src/backend/utils/adt/dbsize.c
@@ -19,12 +19,12 @@
 #include "catalog/pg_authid.h"
 #include "catalog/pg_database.h"
 #include "catalog/pg_tablespace.h"
-#include "commands/dbcommands.h"
 #include "commands/tablespace.h"
 #include "miscadmin.h"
 #include "storage/fd.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
+#include "utils/lsyscache.h"
 #include "utils/numeric.h"
 #include "utils/rel.h"
 #include "utils/relfilenumbermap.h"
diff --git a/src/backend/utils/adt/misc.c b/src/backend/utils/adt/misc.c
index 6fcfd031428..6c5e3438447 100644
--- a/src/backend/utils/adt/misc.c
+++ b/src/backend/utils/adt/misc.c
@@ -26,7 +26,6 @@
 #include "catalog/pg_tablespace.h"
 #include "catalog/pg_type.h"
 #include "catalog/system_fk_info.h"
-#include "commands/dbcommands.h"
 #include "commands/tablespace.h"
 #include "common/keywords.h"
 #include "funcapi.h"
diff --git a/src/backend/utils/adt/regproc.c b/src/backend/utils/adt/regproc.c
index b8bbe95e82e..af17a3421a0 100644
--- a/src/backend/utils/adt/regproc.c
+++ b/src/backend/utils/adt/regproc.c
@@ -25,12 +25,12 @@
 #include "catalog/namespace.h"
 #include "catalog/pg_class.h"
 #include "catalog/pg_collation.h"
+#include "catalog/pg_database.h"
 #include "catalog/pg_operator.h"
 #include "catalog/pg_proc.h"
 #include "catalog/pg_ts_config.h"
 #include "catalog/pg_ts_dict.h"
 #include "catalog/pg_type.h"
-#include "commands/dbcommands.h"
 #include "lib/stringinfo.h"
 #include "mb/pg_wchar.h"
 #include "miscadmin.h"
diff --git a/src/backend/utils/adt/xml.c b/src/backend/utils/adt/xml.c
index 182e8f75db7..7b7396cdf83 100644
--- a/src/backend/utils/adt/xml.c
+++ b/src/backend/utils/adt/xml.c
@@ -84,7 +84,6 @@
 #include "catalog/namespace.h"
 #include "catalog/pg_class.h"
 #include "catalog/pg_type.h"
-#include "commands/dbcommands.h"
 #include "executor/spi.h"
 #include "executor/tablefunc.h"
 #include "fmgr.h"
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 *