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Mon, 8 Jun 2026 07:57:39 +0000 From: Klaus Darilion To: pgsql-general Subject: WAL compatibility between Primary and Standby Server, chained clients Thread-Topic: WAL compatibility between Primary and Standby Server, chained clients Thread-Index: AQHc9xsuPbQUEwwvQUW/qHDR1n6syQ== Date: Mon, 8 Jun 2026 07:57:39 +0000 Message-ID: Accept-Language: de-DE, en-US Content-Language: de-DE X-MS-Has-Attach: X-MS-TNEF-Correlator: msip_labels: authentication-results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=nic.at; x-ms-publictraffictype: Email x-ms-traffictypediagnostic: DBAPR03MB6358:EE_|AM9PR03MB7410:EE_ x-ms-office365-filtering-correlation-id: 87ee7a22-00ae-4207-fdd9-08dec5339c67 x-ms-exchange-senderadcheck: 1 x-ms-exchange-antispam-relay: 0 x-microsoft-antispam: BCL:0;ARA:13230040|366016|1800799024|376014|38070700021|8096899003|3023799007|18002099003|56012099006; x-microsoft-antispam-message-info: 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 x-forefront-antispam-report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:DBAPR03MB6358.eurprd03.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(366016)(1800799024)(376014)(38070700021)(8096899003)(3023799007)(18002099003)(56012099006);DIR:OUT;SFP:1102; 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boundary="_000_DBAPR03MB6358A12B207F441E8B1BF984F11C2DBAPR03MB6358eurp_" MIME-Version: 1.0 X-OriginatorOrg: nic.at X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: DBAPR03MB6358.eurprd03.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: 87ee7a22-00ae-4207-fdd9-08dec5339c67 X-MS-Exchange-CrossTenant-originalarrivaltime: 08 Jun 2026 07:57:39.1144 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 6da68bb1-2470-49a3-8e7a-a343d51e9234 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: 1RejkyWcAGZ9gSdoKTz4cAJCqmvGpluuhr37OD2c/mHgtwH9CkZKUpR1CE+CLnHDVnxFph4F/7ixDElOn/mXDQ== X-MS-Exchange-Transport-CrossTenantHeadersStamped: AM9PR03MB7410 List-Id: List-Help: List-Subscribe: List-Post: List-Owner: List-Archive: Archived-At: Precedence: bulk --_000_DBAPR03MB6358A12B207F441E8B1BF984F11C2DBAPR03MB6358eurp_ Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Hello! I have questions about the streaming replication and about the WALs on the = primary vs. standby servers. How does the standby server decides when to write/rotate WAL files? Is this= in sync how the primary server does this (ie. in the streaming replication= protocol there are also signal when to rotate the WAL files)? Or does the = standby server act totally on its own and decides itself when to rotate WAL= files? In the first case, are the WAL files between primary and standby server ide= ntical (so for example I could use a WAL file from a standby server with th= e base backup from a primary server)? These questions came into my mind as we are doing a backup of the standby s= erver using barman. Our standby server fell out of sync and had to resynced= from the primary. Should a chained-downstream replication client (ie barma= n) automatically resync with the standby or is it necessary to re-initializ= e the replication from the standby to downstream clients? Thanks Klaus -- Klaus Darilion, Head of Operations nic.at GmbH, Jakob-Haringer-Stra=DFe 8/V 5020 Salzburg, Austria --_000_DBAPR03MB6358A12B207F441E8B1BF984F11C2DBAPR03MB6358eurp_ Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Hello!

I have questions about the streaming replication and about the WALs on the = primary vs. standby servers.

How does the standby server decides when to write/rotate WAL files? Is this= in sync how the primary server does this (ie. in the streaming replication= protocol there are also signal when to rotate the WAL files)? Or does the = standby server act totally on its own and decides itself when to rotate WAL files?

In the first case, are the WAL files between primary and standby server ide= ntical (so for example I could use a WAL file from a standby server with th= e base backup from a primary server)?

These questions came into my mind as we are doing a backup of the standby s= erver using barman. Our standby server fell out of sync and had to resynced= from the primary. Should a chained-downstream replication client (ie barma= n) automatically resync with the standby or is it necessary to re-initialize the replication from the stand= by to downstream clients?

Thanks
Klaus



--

Klaus Darilion, Head of O= perations

nic.at GmbH, Jakob-Haring= er-Stra=DFe 8/V

5020 Salzburg, Austria

 

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