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help / color / mirror / Atom feedFrom: Akshay Joshi <[email protected]>
To: Andrew Dunstan <[email protected]>
Cc: Euler Taveira <[email protected]>
Cc: Álvaro Herrera <[email protected]>
Cc: Chao Li <[email protected]>
Cc: japin <[email protected]>
Cc: Quan Zongliang <[email protected]>
Cc: pgsql-hackers <[email protected]>
Subject: Re: [PATCH] Add pg_get_database_ddl() function to reconstruct CREATE DATABASE statement
Date: Fri, 16 Jan 2026 12:53:48 +0530
Message-ID: <CANxoLDd2iMLGc1WsNFywB_jZmCYJON-6g1awwsC_S1Q-PRJDVw@mail.gmail.com> (raw)
In-Reply-To: <CANxoLDcF=eqXB59WcTqCwrp6u5Qw0bUjVSTbRApquSvsYLcPWQ@mail.gmail.com>
References: <CANxoLDdPqyTLyYhBnekFYkaSn_8DBdtf32cH=MLNJc=+BQP=MQ@mail.gmail.com>
<[email protected]>
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<[email protected]>
<CANxoLDeAv5M-HcVnwN6q3RNaBeXRfkR7_3LAvZ=pfLqc8=N8vw@mail.gmail.com>
<[email protected]>
<[email protected]>
<CANxoLDcF=eqXB59WcTqCwrp6u5Qw0bUjVSTbRApquSvsYLcPWQ@mail.gmail.com>
-
1) Implement *uint64* for the flags to provide capacity for up to 64
distinct options.
2) Refactor parse_ddl_options to return the flag set directly rather than
using an *out parameter*.
Please find the attached *v7* patch, which is now ready for review.
On Wed, Jan 14, 2026 at 9:18 PM Akshay Joshi <[email protected]>
wrote:
> I have incorporated Euler’s changes, which modify the declaration and
> definition of the *pg_get_database_ddl* function. Please find the
> attached v6 patch, which is now ready for review. The following updates
> have been made:
>
> 1.
>
> Function signature updated to: pg_get_database_ddl(database_id
> regdatabase, VARIADIC ddl_options text[])
> 2.
>
> Added options *--no-owner* and *--no-tablespace* to omit the OWNER and
> TABLESPACE clauses from the reconstructed DDL.
> 3.
>
> Moved the "*pretty*" parameter into ddl_options for formatted output.
> 4.
>
> Properties such as ENCODING, LOCALE_PROVIDER, TABLESPACE, CONNECTION
> LIMIT, and ALLOW_CONNECTIONS are omitted if they are set to default values.
> 5.
>
> Introduced the *--with-defaults* option to include clauses for
> parameters even when they are at their default values.
> 6.
>
> Standardized formatting to use spaces instead of tabs.
>
> *Usage examples:*
>
> 1. SELECT pg_get_database_ddl('postgres'); // Non pretty-formatted DDL
> 2. SELECT pg_get_database_ddl(16835); // Non pretty-formatted DDL
> 3. SELECT pg_get_database_ddl('postgres', 'pretty'); //
> pretty-formatted DDL
> 4. SELECT pg_get_database_ddl('postgres', '--no-owner',
> '--no-tablespace'); // Omits the Owner and Tablespace clause from the DDL.
> 5. SELECT pg_get_database_ddl('postgres', 'pretty',
> '--with-defaults'); // Includes clauses for parameters that are currently
> at their default values.
>
>
> On Thu, Jan 8, 2026 at 4:57 AM Andrew Dunstan <[email protected]> wrote:
>
>>
>> On 2025-12-12 Fr 10:19 AM, Euler Taveira wrote:
>>
>> On Fri, Dec 12, 2025, at 7:52 AM, Akshay Joshi wrote:
>>
>> On Thu, Dec 11, 2025 at 7:29 PM Euler Taveira <[email protected]> <[email protected]> wrote:
>>
>> Is there any way to obtain the default values directly from the source
>> code itself, or do I need to refer to the documentation? If we rely on
>> the documentation and compare against that, then in the future, if the
>> default values change, we would also need to update our logic
>> accordingly.
>>
>>
>> No, you need to check the documentation. If you are changing the default value,
>> you are breaking compatibility; that rarely happens. If we are really concern
>> about this fact, you can add a test case that creates the object without
>> properties (all default values) and another with all default properties and
>> then compare the output.
>>
>>
>> Maybe the function should have a VERBOSE option that emits all the
>> defaults.
>>
>>
>> Constantly having to check the documentation for default values may
>> feel annoying to some users. Some users run queries with parameters
>> such as encoding, connection limit, and locale using their default
>> values. When they call the pg_get_database_ddl function, it
>> reconstructs the short command based on those defaults.
>>
>>
>> Encoding and locale, ok but I doubt about connection limit.
>>
>> postgres=# SELECT current_user;
>> current_user
>> --------------
>> euler
>> (1 row)
>>
>> postgres=# CREATE DATABASE foo;
>> CREATE DATABASE
>> postgres=# CREATE DATABASE bar OWNER euler;
>> CREATE DATABASE
>>
>> When you are learning a new command, you generally don't set the default value
>> for a property just to be correct. I'm not saying this function shouldn't
>> include OWNER. I'm just suggesting it to be optional. See some arguments
>> below.
>>
>>
>> * OWNER. There is no guarantee that the owner exists in the cluster you will
>> use this output. That's something that pg_dumpall treats separately (see
>> above). Does it mean we should include the owner? No. We can make it an
>> option.
>>
>>
>> If I understand correctly, the owner should be an option provided by
>> the caller of the function, and we reconstruct the Database DDL using
>> that specified owner. Is that right?
>> If so, then in my humble opinion, this is not truly a reconstruction
>> of the existing database object.
>>
>>
>> No. My idea is to have something like the pg_dump --no-owner option. This is
>> important if you are transporting the objects from one cluster to another one.
>> Owner might be different. That's why I'm suggesting it should be optional. It
>> means flexibility. See pg_dump output format that always apply the OWNER as a
>> separate ALTER command.
>>
>>
>> +1
>>
>>
>> * options. Since I mentioned options for some properties (owner, strategy,
>> template), these properties can be accommodated as a VARIADIC argument. The
>> function signature can be something like
>>
>> pg_get_database_ddl(oid, VARIADIC options text[])
>>
>> I would include the pretty print into options too.
>>
>>
>> Same comment as the one I gave for the Owner, if you are referring to
>> these as options to the function.
>>
>>
>> Let me elaborate a bit. As I suggested you can control the output with options.
>> Why? Flexibility.
>>
>> Why am I suggesting such a general purpose implementation? See some of the use
>> cases.
>>
>> 1. object DDL. Check DDL to recreate the object. It is not the exact DDL that
>> the user informed but it produces the same result.
>> 2. clone tool. Clone the objects to recreate the environment for another
>> customer. These objects can be created in the same cluster or in another one.
>> (Of course, global objects don't apply for the same cluster.)
>> 3. dump tool. Dump the commands to recreate the existing objects.
>> 4. diff tool. There are tools like pgquarrel [1] that queries the catalog and
>> compare the results to create commands to turn the target database into the
>> source database. The general purpose functions can be used if the object
>> doesn't exist in the target database. (Of course, it doesn't apply for global
>> objects but again it is a good UI to have all of these pg_get_OBJECT_ddl
>> functions using the same approach.)
>> 5. logical replication. These pg_get_OBJECT_ddl functions can be good
>> candidates to be used in the initial schema replication and even in the DDL
>> replication (if the object doesn't exist in the target database).
>>
>> The "options" parameter is to get the DDL command to serve any of these use
>> cases. There are some properties in a certain object that you *don't* want for
>> whatever reason. See some --no-OBJECT options in pg_dump. Let's say you don't
>> want the TABLESPACE or the table access method while getting the CREATE TABLE
>> DDL because it is different in the other database.
>>
>>
>> +1
>>
>>
>> I received a review comment suggesting the use of tabs. I also looked
>> up PostgreSQL best practices on google, which recommend using tabs for
>> indentation and spaces for alignment. I’m open to updating my code
>> accordingly.
>>
>>
>> I didn't check all of the possible output but the majority uses space instead
>> of tabs. Check psql. If you check the git history (git log --grep=tabs), you
>> will notice that tabs are removed from source code.
>>
>>
>>
>> We should follow the pretty printing style in ruleutils.c, which uses
>> spaces.
>>
>>
>> * permission. I don't think you need to check for permissions inside the
>> function. I wouldn't want a different behavior than pg_dump(all). You can
>> always adjust it in system_functions.sql.
>>
>>
>> We’ve already had extensive discussions on this topic in the same
>> email thread, and ultimately we decided to add the permission check.
>>
>>
>> That's fair. Again, I expect that all of these pg_get_OBJECT_ddl functions use
>> the same approach. We can always relax this restriction in the future.
>>
>>
>>
>> +1
>>
>>
>> cheers
>>
>>
>> andrew
>>
>> --
>> Andrew Dunstan
>> EDB: https://www.enterprisedb.com
>>
>>
Attachments:
[application/octet-stream] v7-0001-Add-pg_get_database_ddl-function-to-reconstruct-CREATE.patch (26.4K, 3-v7-0001-Add-pg_get_database_ddl-function-to-reconstruct-CREATE.patch)
download | inline diff:
From ece82b36f2cd7cd9b0364a08a07d60f6a9bd6d49 Mon Sep 17 00:00:00 2001
From: Akshay Joshi <[email protected]>
Date: Wed, 24 Sep 2025 17:47:59 +0530
Subject: [PATCH v7] 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 <[email protected]>
Reviewed-by: Álvaro Herrera <[email protected]>
Reviewed-by: Quan Zongliang <[email protected]>
Reviewed-by: Japin Li <[email protected]>
Reviewed-by: Chao Li <[email protected]>
Reviewed-by: Euler Taveira <[email protected]>
---
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..c6b59790655 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 0x00000001
+#define PG_DDL_WITH_DEFAULTS 0x00000002
+#define PG_DDL_NO_OWNER 0x00000004
+#define PG_DDL_NO_TABLESPACE 0x00000008
+
+
/* 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 uint64
+parse_ddl_options(ArrayType *ddl_options)
+{
+ uint64 flags = 0;
+ Datum *options;
+ bool *nulls;
+ int n_options;
+ int i;
+
+ /* If no options provided, return the empty bitmask */
+ if (ddl_options == NULL)
+ return flags;
+
+ 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 strings to bitmask flags */
+ 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);
+
+ return flags;
+}
+
+/*
+ * 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;
+ uint64 ddl_flags = 0;
+ bool is_with_defaults = false;
+
+ /* Call DDL options parser */
+ ddl_flags = parse_ddl_options(ddl_options);
+
+ /* 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 894b6a1b6d6..53d623de58f 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..84ef61b4f3d
--- /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
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Subject: Re: [PATCH] Add pg_get_database_ddl() function to reconstruct CREATE DATABASE statement
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