From 380108794f704e34971c5899aa4b63502b494c0a Mon Sep 17 00:00:00 2001
From: Akshay Joshi <akshay.joshi@enterprisedb.com>
Date: Wed, 24 Sep 2025 17:47:59 +0530
Subject: [PATCH v6] Add pg_get_database_ddl() function to reconstruct CREATE
 DATABASE statements.
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

This adds a new system function, pg_get_database_ddl(database_name/database_oid, ddl_options),
which reconstructs the CREATE DATABASE statement for a given database name or database oid.
Supported ddl_options are 'pretty', '--no-owner', '--no-tablespace' and '--with-defaults'.

Usage:
  SELECT pg_get_database_ddl('postgres'); // Non pretty-formatted DDL
  SELECT pg_get_database_ddl(16835); // Non pretty-formatted DDL
  SELECT pg_get_database_ddl('postgres', 'pretty'); // pretty-formatted DDL
  SELECT pg_get_database_ddl('postgres', '--no-owner', '--no-tablespace'); // Omits the Owner and Tablespace clause from the DDL.
  SELECT pg_get_database_ddl('postgres', 'pretty', '--with-defaults'); // Includes clauses for parameters that are currently at their default values.

Reference: PG-150
Author: Akshay Joshi <akshay.joshi@enterprisedb.com>
Reviewed-by: Álvaro Herrera <alvherre@kurilemu.de>
Reviewed-by: Quan Zongliang <quanzongliang@yeah.net>
Reviewed-by: Japin Li <japinli@hotmail.com>
Reviewed-by: Chao Li <li.evan.chao@gmail.com>
Reviewed-by: Euler Taveira <euler@eulerto.com>
---
 doc/src/sgml/func/func-info.sgml         |  77 ++++++
 src/backend/catalog/system_functions.sql |   6 +
 src/backend/utils/adt/ruleutils.c        | 291 +++++++++++++++++++++++
 src/include/catalog/pg_proc.dat          |   6 +
 src/include/utils/ddl_defaults.h         |  37 +++
 src/test/regress/expected/database.out   | 134 +++++++++++
 src/test/regress/sql/database.sql        |  91 +++++++
 7 files changed, 642 insertions(+)
 create mode 100644 src/include/utils/ddl_defaults.h

diff --git a/doc/src/sgml/func/func-info.sgml b/doc/src/sgml/func/func-info.sgml
index 175f18315cd..2250031bb83 100644
--- a/doc/src/sgml/func/func-info.sgml
+++ b/doc/src/sgml/func/func-info.sgml
@@ -3830,4 +3830,81 @@ acl      | {postgres=arwdDxtm/postgres,foo=r/postgres}
 
   </sect2>
 
+  <sect2 id="functions-get-object-ddl">
+   <title>Get Object DDL Functions</title>
+
+   <para>
+    The functions described in <xref linkend="functions-get-object-ddl-table"/>
+    return the Data Definition Language (DDL) statement for any given database object.
+    This feature is implemented as a set of distinct functions for each object type.
+   </para>
+
+   <table id="functions-get-object-ddl-table">
+    <title>Get Object DDL Functions</title>
+    <tgroup cols="1">
+     <thead>
+      <row>
+       <entry role="func_table_entry"><para role="func_signature">
+        Function
+       </para>
+       <para>
+        Description
+       </para></entry>
+      </row>
+     </thead>
+
+     <tbody>
+      <row>
+       <entry role="func_table_entry"><para role="func_signature">
+        <indexterm>
+         <primary>pg_get_database_ddl</primary>
+        </indexterm>
+        <function>pg_get_database_ddl</function> ( <parameter>database_id</parameter> <type>regdatabase</type> <optional>, <literal>VARIADIC</literal> <parameter>ddl_options</parameter> <type>text[]</type> </optional> )
+        <returnvalue>text</returnvalue>
+       </para>
+       <para>
+        Reconstructs the <command>CREATE DATABASE</command> statement from the
+        system catalogs for a specified database. The first argument is the OID or
+        name of the database. The optional variadic argument is an array of text
+        flags to control the output. Supported options include
+        <literal>pretty</literal>, <literal>--no-owner</literal>,
+        <literal>--no-tablespace</literal>, and <literal>--with-defaults</literal>.
+        </para></entry>
+      </row>
+     </tbody>
+    </tgroup>
+   </table>
+
+  <para>
+    The <parameter>ddl_options</parameter> for <function>pg_get_database_ddl</function>
+    provide fine-grained control over the generated SQL:
+    <itemizedlist>
+    <listitem>
+      <para>
+      <literal>pretty</literal>: Adds newlines and indentation for better readability.
+      </para>
+    </listitem>
+    <listitem>
+      <para>
+      <literal>--no-owner</literal>: Omits the <literal>OWNER</literal> clause from
+      the reconstructed statement.
+      </para>
+    </listitem>
+    <listitem>
+      <para>
+      <literal>--no-tablespace</literal>: Omits the <literal>TABLESPACE</literal> clause.
+      </para>
+    </listitem>
+    <listitem>
+      <para>
+      <literal>--with-defaults</literal>: Includes clauses for parameters that are
+      currently at their default values (e.g., <literal>CONNECTION LIMIT -1</literal>),
+      which are normally omitted for brevity.
+      </para>
+    </listitem>
+    </itemizedlist>
+  </para>
+
+  </sect2>
+
   </sect1>
diff --git a/src/backend/catalog/system_functions.sql b/src/backend/catalog/system_functions.sql
index eb9e31ae1bf..16c0d52479a 100644
--- a/src/backend/catalog/system_functions.sql
+++ b/src/backend/catalog/system_functions.sql
@@ -657,6 +657,12 @@ LANGUAGE INTERNAL
 STRICT VOLATILE PARALLEL UNSAFE
 AS 'pg_replication_origin_session_setup';
 
+CREATE OR REPLACE FUNCTION
+  pg_get_database_ddl(database_id regdatabase, VARIADIC ddl_options text[] DEFAULT '{}')
+RETURNS text
+LANGUAGE internal
+AS 'pg_get_database_ddl';
+
 --
 -- The default permissions for functions mean that anyone can execute them.
 -- A number of functions shouldn't be executable by just anyone, but rather
diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c
index 033b625f3fc..4c6c8532bf3 100644
--- a/src/backend/utils/adt/ruleutils.c
+++ b/src/backend/utils/adt/ruleutils.c
@@ -28,6 +28,7 @@
 #include "catalog/pg_authid.h"
 #include "catalog/pg_collation.h"
 #include "catalog/pg_constraint.h"
+#include "catalog/pg_database.h"
 #include "catalog/pg_depend.h"
 #include "catalog/pg_language.h"
 #include "catalog/pg_opclass.h"
@@ -57,8 +58,10 @@
 #include "rewrite/rewriteHandler.h"
 #include "rewrite/rewriteManip.h"
 #include "rewrite/rewriteSupport.h"
+#include "utils/acl.h"
 #include "utils/array.h"
 #include "utils/builtins.h"
+#include "utils/ddl_defaults.h"
 #include "utils/fmgroids.h"
 #include "utils/guc.h"
 #include "utils/hsearch.h"
@@ -89,11 +92,22 @@
 #define PRETTYFLAG_INDENT		0x0002
 #define PRETTYFLAG_SCHEMA		0x0004
 
+/* DDL Options flags */
+#define PG_DDL_PRETTY_INDENT	0x0001
+#define PG_DDL_WITH_DEFAULTS	0x0002
+#define PG_DDL_NO_OWNER			0x0004
+#define PG_DDL_NO_TABLESPACE	0x0008
+
+
 /* Standard conversion of a "bool pretty" option to detailed flags */
 #define GET_PRETTY_FLAGS(pretty) \
 	((pretty) ? (PRETTYFLAG_PAREN | PRETTYFLAG_INDENT | PRETTYFLAG_SCHEMA) \
 	 : PRETTYFLAG_INDENT)
 
+#define GET_DDL_PRETTY_FLAGS(pretty) \
+	((pretty) ? (PRETTYFLAG_PAREN | PRETTYFLAG_INDENT | PRETTYFLAG_SCHEMA) \
+	 : 0)
+
 /* Default line length for pretty-print wrapping: 0 means wrap always */
 #define WRAP_COLUMN_DEFAULT		0
 
@@ -546,6 +560,11 @@ static void get_json_table_nested_columns(TableFunc *tf, JsonTablePlan *plan,
 										  deparse_context *context,
 										  bool showimplicit,
 										  bool needcomma);
+static void get_formatted_string(StringInfo buf,
+								 int prettyFlags,
+								 int nSpaces,
+								 const char *fmt,...) pg_attribute_printf(4, 5);
+static char *pg_get_database_ddl_worker(Oid db_oid, ArrayType *ddl_options);
 
 #define only_marker(rte)  ((rte)->inh ? "" : "ONLY ")
 
@@ -13743,3 +13762,275 @@ get_range_partbound_string(List *bound_datums)
 
 	return buf.data;
 }
+
+/*
+ * get_formatted_string
+ *
+ * Return a formatted version of the string.
+ *
+ * prettyFlags - Based on prettyFlags the output includes spaces and
+ *               newlines (\n).
+ * nSpaces - indent with specified number of space characters.
+ * fmt - printf-style format string used by appendStringInfoVA.
+ */
+static void
+get_formatted_string(StringInfo buf, int prettyFlags, int nSpaces, const char *fmt,...)
+{
+	va_list		args;
+
+	if (prettyFlags & PRETTYFLAG_INDENT)
+	{
+		appendStringInfoChar(buf, '\n');
+		/* Indent with spaces */
+		for (int i = 0; i < nSpaces; i++)
+		{
+			appendStringInfoChar(buf, ' ');
+		}
+	}
+	else
+		appendStringInfoChar(buf, ' ');
+
+	va_start(args, fmt);
+	appendStringInfoVA(buf, fmt, args);
+	va_end(args);
+}
+
+/**
+ * parse_ddl_options - Generic helper to parse variadic text options
+ * ddl_options: The ArrayType from PG_GETARG_ARRAYTYPE_P
+ * flags: Bitmask to set options while parsing DDL options.
+ */
+static void
+parse_ddl_options(ArrayType *ddl_options, int *flags)
+{
+	Datum	   *options;
+	bool	   *nulls;
+	int			n_options;
+	int			i;
+
+	/* Default to 0 (all options off) */
+	if (flags)
+		*flags = 0;
+
+	if (ddl_options == NULL || flags == NULL)
+		return;
+
+	deconstruct_array(ddl_options,
+					  TEXTOID, -1, false, 'i',
+					  &options, &nulls, &n_options);
+
+	for (i = 0; i < n_options; i++)
+	{
+		char	   *opt;
+
+		if (nulls[i])
+			continue;
+
+		opt = TextDatumGetCString(options[i]);
+
+		/* Map all strings to the single bitmask */
+		if (strcmp(opt, "pretty") == 0)
+			*flags |= PG_DDL_PRETTY_INDENT;
+		else if (strcmp(opt, "--no-owner") == 0)
+			*flags |= PG_DDL_NO_OWNER;
+		else if (strcmp(opt, "--no-tablespace") == 0)
+			*flags |= PG_DDL_NO_TABLESPACE;
+		else if (strcmp(opt, "--with-defaults") == 0)
+			*flags |= PG_DDL_WITH_DEFAULTS;
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					 errmsg("unrecognized option: %s", opt)));
+
+		pfree(opt);
+	}
+
+	pfree(options);
+	pfree(nulls);
+}
+
+/*
+ * pg_get_database_ddl
+ *
+ * Generate a CREATE DATABASE statement for the specified database name or oid.
+ *
+ * db_oid - OID/Name of the database for which to generate the DDL.
+ * ddl_options - Array of text options to modify the output.
+ */
+Datum
+pg_get_database_ddl(PG_FUNCTION_ARGS)
+{
+	Oid			db_oid = PG_GETARG_OID(0);
+	ArrayType  *ddl_options = PG_GETARG_ARRAYTYPE_P(1);
+	char	   *res;
+
+	res = pg_get_database_ddl_worker(db_oid, ddl_options);
+
+	if (res == NULL)
+		PG_RETURN_NULL();
+
+	PG_RETURN_TEXT_P(string_to_text(res));
+}
+
+static char *
+pg_get_database_ddl_worker(Oid db_oid, ArrayType *ddl_options)
+{
+	char	   *dbowner = NULL;
+	bool		attr_isnull;
+	Datum		dbvalue;
+	HeapTuple	tuple_database;
+	Form_pg_database dbform;
+	StringInfoData buf;
+	AclResult	aclresult;
+
+	/* Variables for ddl_options parsing */
+	int			pretty_flags = 0;
+	int			ddl_flags = 0;
+	bool		is_with_defaults = false;
+
+	/* Call DDL options parser */
+	parse_ddl_options(ddl_options, &ddl_flags);
+
+	/* Set the appropriate flags */
+	if (ddl_flags & PG_DDL_PRETTY_INDENT)
+		pretty_flags = GET_DDL_PRETTY_FLAGS(1);
+
+	is_with_defaults = (ddl_flags & PG_DDL_WITH_DEFAULTS) ? true : false;
+
+	/*
+	 * User must have connect privilege for target database.
+	 */
+	aclresult = object_aclcheck(DatabaseRelationId, db_oid, GetUserId(),
+								ACL_CONNECT);
+	if (aclresult != ACLCHECK_OK &&
+		!has_privs_of_role(GetUserId(), ROLE_PG_READ_ALL_STATS))
+	{
+		aclcheck_error(aclresult, OBJECT_DATABASE,
+					   get_database_name(db_oid));
+	}
+
+	/* Look up the database in pg_database */
+	tuple_database = SearchSysCache1(DATABASEOID, ObjectIdGetDatum(db_oid));
+	if (!HeapTupleIsValid(tuple_database))
+		ereport(ERROR,
+				errcode(ERRCODE_UNDEFINED_OBJECT),
+				errmsg("database with oid %u does not exist", db_oid));
+
+	dbform = (Form_pg_database) GETSTRUCT(tuple_database);
+
+	initStringInfo(&buf);
+
+	/* Look up the owner in the system catalog */
+	if (OidIsValid(dbform->datdba))
+		dbowner = GetUserNameFromId(dbform->datdba, false);
+
+	/* Build the CREATE DATABASE statement */
+	appendStringInfo(&buf, "CREATE DATABASE %s",
+					 quote_identifier(dbform->datname.data));
+	get_formatted_string(&buf, pretty_flags, 4, "WITH");
+
+	/* Set the OWNER in the DDL if --no-owner is not specified */
+	if (OidIsValid(dbform->datdba) && !(ddl_flags & PG_DDL_NO_OWNER))
+	{
+		get_formatted_string(&buf, pretty_flags, 8, "OWNER = %s",
+							 quote_identifier(dbowner));
+	}
+
+	/* Set the ENCODING in the DDL */
+	if (dbform->encoding != 0)
+	{
+		/* If it's with defaults, we skip default encoding check */
+		if (is_with_defaults ||
+			(pg_strcasecmp(pg_encoding_to_char(dbform->encoding),
+						   DDL_DEFAULTS.DATABASE.ENCODING) != 0))
+		{
+			get_formatted_string(&buf, pretty_flags, 8, "ENCODING = %s",
+								 quote_literal_cstr(
+													pg_encoding_to_char(dbform->encoding)));
+		}
+	}
+
+	/* Fetch the value of LC_COLLATE */
+	dbvalue = SysCacheGetAttr(DATABASEOID, tuple_database,
+							  Anum_pg_database_datcollate, &attr_isnull);
+	if (!attr_isnull)
+		get_formatted_string(&buf, pretty_flags, 8, "LC_COLLATE = %s",
+							 quote_literal_cstr(TextDatumGetCString(dbvalue)));
+	/* Fetch the value of LC_CTYPE */
+	dbvalue = SysCacheGetAttr(DATABASEOID, tuple_database,
+							  Anum_pg_database_datctype, &attr_isnull);
+	if (!attr_isnull)
+		get_formatted_string(&buf, pretty_flags, 8, "LC_CTYPE = %s",
+							 quote_literal_cstr(TextDatumGetCString(dbvalue)));
+	/* Fetch the value of LOCALE */
+	dbvalue = SysCacheGetAttr(DATABASEOID, tuple_database,
+							  Anum_pg_database_datlocale, &attr_isnull);
+	if (!attr_isnull && dbform->datlocprovider == COLLPROVIDER_BUILTIN)
+		get_formatted_string(&buf, pretty_flags, 8, "BUILTIN_LOCALE = %s",
+							 quote_literal_cstr(TextDatumGetCString(dbvalue)));
+	else if (!attr_isnull && dbform->datlocprovider == COLLPROVIDER_ICU)
+		get_formatted_string(&buf, pretty_flags, 8, "ICU_LOCALE = %s",
+							 quote_literal_cstr(TextDatumGetCString(dbvalue)));
+	else if (!attr_isnull)
+		get_formatted_string(&buf, pretty_flags, 8, "LOCALE = %s",
+							 quote_literal_cstr(TextDatumGetCString(dbvalue)));
+
+	/* Fetch the value of ICU_RULES */
+	dbvalue = SysCacheGetAttr(DATABASEOID, tuple_database,
+							  Anum_pg_database_daticurules, &attr_isnull);
+	if (!attr_isnull && dbform->datlocprovider == COLLPROVIDER_ICU)
+		get_formatted_string(&buf, pretty_flags, 8, "ICU_RULES = %s",
+							 quote_literal_cstr(TextDatumGetCString(dbvalue)));
+
+	/* Fetch the value of COLLATION_VERSION */
+	dbvalue = SysCacheGetAttr(DATABASEOID, tuple_database,
+							  Anum_pg_database_datcollversion, &attr_isnull);
+	if (!attr_isnull)
+		get_formatted_string(&buf, pretty_flags, 8, "COLLATION_VERSION = %s",
+							 quote_literal_cstr(TextDatumGetCString(dbvalue)));
+
+	/* Set the appropriate LOCALE_PROVIDER */
+	if (dbform->datlocprovider == COLLPROVIDER_BUILTIN)
+		get_formatted_string(&buf, pretty_flags, 8, "LOCALE_PROVIDER = builtin");
+	else if (dbform->datlocprovider == COLLPROVIDER_ICU)
+		get_formatted_string(&buf, pretty_flags, 8, "LOCALE_PROVIDER = icu");
+	else if (is_with_defaults)
+		get_formatted_string(&buf, pretty_flags, 8, "LOCALE_PROVIDER = libc");
+
+	/* Set the TABLESPACE in the DDL if --no-tablespace is not specified */
+	if (OidIsValid(dbform->dattablespace) && !(ddl_flags & PG_DDL_NO_TABLESPACE))
+	{
+		/* Get the tablespace name respective to the given tablespace oid */
+		char	   *dbTablespace = get_tablespace_name(dbform->dattablespace);
+
+		/* If it's with defaults, we skip default tablespace check */
+		if (is_with_defaults ||
+			(pg_strcasecmp(dbTablespace, DDL_DEFAULTS.DATABASE.TABLESPACE) != 0))
+			get_formatted_string(&buf, pretty_flags, 8, "TABLESPACE = %s",
+								 quote_identifier(dbTablespace));
+	}
+
+	if (is_with_defaults ||
+		(dbform->datallowconn != DDL_DEFAULTS.DATABASE.ALLOW_CONN))
+	{
+		get_formatted_string(&buf, pretty_flags, 8, "ALLOW_CONNECTIONS = %s",
+							 dbform->datallowconn ? "true" : "false");
+	}
+
+	if (is_with_defaults ||
+		(dbform->datconnlimit != DDL_DEFAULTS.DATABASE.CONN_LIMIT))
+	{
+		get_formatted_string(&buf, pretty_flags, 8, "CONNECTION LIMIT = %d",
+							 dbform->datconnlimit);
+	}
+
+	if (dbform->datistemplate)
+		get_formatted_string(&buf, pretty_flags, 8, "IS_TEMPLATE = %s",
+							 dbform->datistemplate ? "true" : "false");
+
+	appendStringInfoChar(&buf, ';');
+
+	ReleaseSysCache(tuple_database);
+
+	return buf.data;
+}
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 2ac69bf2df5..181f3e76877 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -4030,6 +4030,12 @@
   proname => 'pg_get_function_sqlbody', provolatile => 's',
   prorettype => 'text', proargtypes => 'oid',
   prosrc => 'pg_get_function_sqlbody' },
+{ oid => '9492', descr => 'get CREATE statement for database name and oid',
+  proname => 'pg_get_database_ddl', proisstrict => 'f', prorettype => 'text',
+  proargtypes => 'regdatabase _text',
+  proargmodes => '{i,v}',
+  proallargtypes => '{regdatabase,_text}',
+  prosrc => 'pg_get_database_ddl' },
 
 { oid => '1686', descr => 'list of SQL keywords',
   proname => 'pg_get_keywords', procost => '10', prorows => '500',
diff --git a/src/include/utils/ddl_defaults.h b/src/include/utils/ddl_defaults.h
new file mode 100644
index 00000000000..312fdc1376d
--- /dev/null
+++ b/src/include/utils/ddl_defaults.h
@@ -0,0 +1,37 @@
+/*-------------------------------------------------------------------------
+ *
+ * ddl_defaults.h
+ *	  Declarations for DDL defaults.
+ *
+ * Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/utils/ddl_defaults.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef DDL_DEFAULTS_H
+#define DDL_DEFAULTS_H
+
+static const struct
+{
+	struct
+	{
+		const char *ENCODING;
+		const char *TABLESPACE;
+		int			CONN_LIMIT;
+		bool		ALLOW_CONN;
+	} DATABASE;
+
+	/* Add more object types as needed */
+} DDL_DEFAULTS = {
+
+	.DATABASE = {
+		.ENCODING = "UTF8",
+		.TABLESPACE = "pg_default",
+		.CONN_LIMIT = -1,
+		.ALLOW_CONN = true,
+	}
+};
+
+#endif      /* DDL_DEFAULTS_H */
\ No newline at end of file
diff --git a/src/test/regress/expected/database.out b/src/test/regress/expected/database.out
index 6b879b0f62a..eb3a13bcf9e 100644
--- a/src/test/regress/expected/database.out
+++ b/src/test/regress/expected/database.out
@@ -1,3 +1,57 @@
+--
+-- Reconstruct DDL
+--
+-- To produce stable regression test output, it's usually necessary to
+-- ignore collation and locale related details. This filter
+-- functions removes collation and locale related details.
+CREATE OR REPLACE FUNCTION ddl_filter(ddl_input TEXT)
+RETURNS TEXT AS $$
+DECLARE
+    cleaned_ddl TEXT;
+BEGIN
+    -- Remove %LOCALE_PROVIDER% placeholders
+    cleaned_ddl := regexp_replace(
+        ddl_input,
+        '\s*\mLOCALE_PROVIDER\M\s*=\s*([''"]?[^''"\s]+[''"]?)',
+        '',
+        'gi'
+    );
+
+	-- Remove LC_COLLATE assignments
+    cleaned_ddl := regexp_replace(
+        cleaned_ddl,
+        '\s*LC_COLLATE\s*=\s*([''"])[^''"]*\1',
+        '',
+        'gi'
+    );
+
+    -- Remove LC_CTYPE assignments
+    cleaned_ddl := regexp_replace(
+        cleaned_ddl,
+        '\s*LC_CTYPE\s*=\s*([''"])[^''"]*\1',
+        '',
+        'gi'
+    );
+
+    -- Remove %LOCALE% placeholders
+    cleaned_ddl := regexp_replace(
+        cleaned_ddl,
+        '\s*\S*LOCALE\S*\s*=?\s*([''"])[^''"]*\1',
+		'',
+		'gi'
+	);
+
+    -- Remove %COLLATION% placeholders
+    cleaned_ddl := regexp_replace(
+        cleaned_ddl,
+        '\s*\S*COLLATION\S*\s*=?\s*([''"])[^''"]*\1',
+        '',
+        'gi'
+    );
+
+    RETURN cleaned_ddl;
+END;
+$$ LANGUAGE plpgsql;
 CREATE DATABASE regression_tbd
 	ENCODING utf8 LC_COLLATE "C" LC_CTYPE "C" TEMPLATE template0;
 ALTER DATABASE regression_tbd RENAME TO regression_utf8;
@@ -16,6 +70,86 @@ CREATE ROLE regress_datdba_before;
 CREATE ROLE regress_datdba_after;
 ALTER DATABASE regression_utf8 OWNER TO regress_datdba_before;
 REASSIGN OWNED BY regress_datdba_before TO regress_datdba_after;
+-- Test pg_get_database_ddl
+-- Database doesn't exists
+SELECT pg_get_database_ddl('regression_database');
+ERROR:  database "regression_database" does not exist
+LINE 1: SELECT pg_get_database_ddl('regression_database');
+                                   ^
+-- Test NULL value
+SELECT pg_get_database_ddl(NULL);
+ERROR:  database with oid 0 does not exist
+-- Without pretty
+SELECT ddl_filter(pg_get_database_ddl('regression_utf8'));
+                                        ddl_filter                                         
+-------------------------------------------------------------------------------------------
+ CREATE DATABASE regression_utf8 WITH OWNER = regress_datdba_after CONNECTION LIMIT = 123;
+(1 row)
+
+-- With No Owner
+SELECT ddl_filter(pg_get_database_ddl('regression_utf8', '--no-owner'));
+                          ddl_filter                          
+--------------------------------------------------------------
+ CREATE DATABASE regression_utf8 WITH CONNECTION LIMIT = 123;
+(1 row)
+
+-- With No Tablespace
+SELECT ddl_filter(pg_get_database_ddl('regression_utf8', '--no-tablespace'));
+                                        ddl_filter                                         
+-------------------------------------------------------------------------------------------
+ CREATE DATABASE regression_utf8 WITH OWNER = regress_datdba_after CONNECTION LIMIT = 123;
+(1 row)
+
+-- With Defaults
+SELECT ddl_filter(pg_get_database_ddl('regression_utf8', '--with-defaults'));
+                                                                          ddl_filter                                                                          
+--------------------------------------------------------------------------------------------------------------------------------------------------------------
+ CREATE DATABASE regression_utf8 WITH OWNER = regress_datdba_after ENCODING = 'UTF8' TABLESPACE = pg_default ALLOW_CONNECTIONS = true CONNECTION LIMIT = 123;
+(1 row)
+
+-- With No Owner, No Tablespace and With Defaults
+SELECT ddl_filter(pg_get_database_ddl('regression_utf8', '--no-owner', '--no-tablespace', '--with-defaults'));
+                                               ddl_filter                                                
+---------------------------------------------------------------------------------------------------------
+ CREATE DATABASE regression_utf8 WITH ENCODING = 'UTF8' ALLOW_CONNECTIONS = true CONNECTION LIMIT = 123;
+(1 row)
+
+-- With Pretty formatted
+\pset format unaligned
+SELECT ddl_filter(pg_get_database_ddl('regression_utf8', 'pretty'));
+ddl_filter
+CREATE DATABASE regression_utf8
+    WITH
+        OWNER = regress_datdba_after
+        CONNECTION LIMIT = 123;
+(1 row)
+-- With No Owner and No Tablespace
+SELECT ddl_filter(pg_get_database_ddl('regression_utf8', 'pretty', '--no-owner', '--no-tablespace'));
+ddl_filter
+CREATE DATABASE regression_utf8
+    WITH
+        CONNECTION LIMIT = 123;
+(1 row)
+-- With Defaults
+SELECT ddl_filter(pg_get_database_ddl('regression_utf8', 'pretty', '--with-defaults'));
+ddl_filter
+CREATE DATABASE regression_utf8
+    WITH
+        OWNER = regress_datdba_after
+        ENCODING = 'UTF8'
+        TABLESPACE = pg_default
+        ALLOW_CONNECTIONS = true
+        CONNECTION LIMIT = 123;
+(1 row)
+-- With No Owner, No Tablespace and With Defaults
+SELECT ddl_filter(pg_get_database_ddl('regression_utf8', 'pretty', '--no-owner', '--no-tablespace', '--with-defaults'));
+ddl_filter
+CREATE DATABASE regression_utf8
+    WITH
+        ENCODING = 'UTF8'
+        ALLOW_CONNECTIONS = true
+        CONNECTION LIMIT = 123;
+(1 row)
 DROP DATABASE regression_utf8;
 DROP ROLE regress_datdba_before;
 DROP ROLE regress_datdba_after;
diff --git a/src/test/regress/sql/database.sql b/src/test/regress/sql/database.sql
index 4ef36127291..918b28c47da 100644
--- a/src/test/regress/sql/database.sql
+++ b/src/test/regress/sql/database.sql
@@ -1,3 +1,59 @@
+--
+-- Reconstruct DDL
+--
+-- To produce stable regression test output, it's usually necessary to
+-- ignore collation and locale related details. This filter
+-- functions removes collation and locale related details.
+
+CREATE OR REPLACE FUNCTION ddl_filter(ddl_input TEXT)
+RETURNS TEXT AS $$
+DECLARE
+    cleaned_ddl TEXT;
+BEGIN
+    -- Remove %LOCALE_PROVIDER% placeholders
+    cleaned_ddl := regexp_replace(
+        ddl_input,
+        '\s*\mLOCALE_PROVIDER\M\s*=\s*([''"]?[^''"\s]+[''"]?)',
+        '',
+        'gi'
+    );
+
+	-- Remove LC_COLLATE assignments
+    cleaned_ddl := regexp_replace(
+        cleaned_ddl,
+        '\s*LC_COLLATE\s*=\s*([''"])[^''"]*\1',
+        '',
+        'gi'
+    );
+
+    -- Remove LC_CTYPE assignments
+    cleaned_ddl := regexp_replace(
+        cleaned_ddl,
+        '\s*LC_CTYPE\s*=\s*([''"])[^''"]*\1',
+        '',
+        'gi'
+    );
+
+    -- Remove %LOCALE% placeholders
+    cleaned_ddl := regexp_replace(
+        cleaned_ddl,
+        '\s*\S*LOCALE\S*\s*=?\s*([''"])[^''"]*\1',
+		'',
+		'gi'
+	);
+
+    -- Remove %COLLATION% placeholders
+    cleaned_ddl := regexp_replace(
+        cleaned_ddl,
+        '\s*\S*COLLATION\S*\s*=?\s*([''"])[^''"]*\1',
+        '',
+        'gi'
+    );
+
+    RETURN cleaned_ddl;
+END;
+$$ LANGUAGE plpgsql;
+
 CREATE DATABASE regression_tbd
 	ENCODING utf8 LC_COLLATE "C" LC_CTYPE "C" TEMPLATE template0;
 ALTER DATABASE regression_tbd RENAME TO regression_utf8;
@@ -19,6 +75,41 @@ CREATE ROLE regress_datdba_after;
 ALTER DATABASE regression_utf8 OWNER TO regress_datdba_before;
 REASSIGN OWNED BY regress_datdba_before TO regress_datdba_after;
 
+-- Test pg_get_database_ddl
+-- Database doesn't exists
+SELECT pg_get_database_ddl('regression_database');
+
+-- Test NULL value
+SELECT pg_get_database_ddl(NULL);
+
+-- Without pretty
+SELECT ddl_filter(pg_get_database_ddl('regression_utf8'));
+
+-- With No Owner
+SELECT ddl_filter(pg_get_database_ddl('regression_utf8', '--no-owner'));
+
+-- With No Tablespace
+SELECT ddl_filter(pg_get_database_ddl('regression_utf8', '--no-tablespace'));
+
+-- With Defaults
+SELECT ddl_filter(pg_get_database_ddl('regression_utf8', '--with-defaults'));
+
+-- With No Owner, No Tablespace and With Defaults
+SELECT ddl_filter(pg_get_database_ddl('regression_utf8', '--no-owner', '--no-tablespace', '--with-defaults'));
+
+-- With Pretty formatted
+\pset format unaligned
+SELECT ddl_filter(pg_get_database_ddl('regression_utf8', 'pretty'));
+
+-- With No Owner and No Tablespace
+SELECT ddl_filter(pg_get_database_ddl('regression_utf8', 'pretty', '--no-owner', '--no-tablespace'));
+
+-- With Defaults
+SELECT ddl_filter(pg_get_database_ddl('regression_utf8', 'pretty', '--with-defaults'));
+
+-- With No Owner, No Tablespace and With Defaults
+SELECT ddl_filter(pg_get_database_ddl('regression_utf8', 'pretty', '--no-owner', '--no-tablespace', '--with-defaults'));
+
 DROP DATABASE regression_utf8;
 DROP ROLE regress_datdba_before;
 DROP ROLE regress_datdba_after;
-- 
2.51.0

