From: Amit Langote <amitlan@postgresql.org>
Date: Fri, 17 Apr 2026 04:19:56 +0000 (+0900)
Subject: Reject invalid databases in pg_get_database_ddl()
X-Git-Url: http://git.ipfire.org/gitweb/?a=commitdiff_plain;h=cda0c4c5d6f581cddaa24cde02c583d1c8f5521d;p=thirdparty%2Fpostgresql.git

Reject invalid databases in pg_get_database_ddl()

An invalid database has datconnlimit set to -2.  pg_get_database_ddl()
emits this verbatim as CONNECTION LIMIT = -2, which ALTER DATABASE
rejects.  Error out early instead.

Reported-by: Lakshmi N <lakshmin.jhs@gmail.com>
Author: Lakshmi N <lakshmin.jhs@gmail.com>
Reviewed-by: Amit Langote <amitlangote09@gmail.com>
Reviewed-by: Euler Taveira <euler@eulerto.com>
Reviewed-by: Hu Xunqi <huxunqi.08@gmail.com>
Discussion: https://postgr.es/m/CA+3i_M8m1k2gFch+tU0JmAQh9FRV+pFrfTXDrJo+BqmwsTmOhg@mail.gmail.com
---

diff --git a/src/backend/utils/adt/ddlutils.c b/src/backend/utils/adt/ddlutils.c
index c4f9f86c43e..d83cda3342e 100644
--- a/src/backend/utils/adt/ddlutils.c
+++ b/src/backend/utils/adt/ddlutils.c
@@ -887,6 +887,16 @@ pg_get_database_ddl_internal(Oid dbid, bool pretty,
 	dbform = (Form_pg_database) GETSTRUCT(tuple);
 	dbname = pstrdup(NameStr(dbform->datname));
 
+	/*
+	 * Reject invalid databases. Deparsing a pg_database row in invalid state
+	 * can produce SQL that is not executable, such as CONNECTION LIMIT = -2.
+	 */
+	if (database_is_invalid_form(dbform))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("cannot generate DDL for invalid database \"%s\"",
+						dbname)));
+
 	/*
 	 * We don't support generating DDL for system databases.  The primary
 	 * reason for this is that users shouldn't be recreating them.