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Merge pull request #222127 from AwdotiaRomanowna/20221221-read-replica-metrics
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‎articles/postgresql/flexible-server/concepts-logical.md

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@@ -29,6 +29,7 @@ Logical replication and logical decoding have several similarities. They both:
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The two technologies have their differences:
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Logical replication:
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* Allows you to specify a table or set of tables to be replicated.
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1. Connect to the publisher database. Create a table and add some data.
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```SQL
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CREATE TABLE basic(id SERIAL, name varchar(40));
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CREATE TABLE basic(id SERIAL, name TEXT);
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INSERT INTO basic(name) VALUES ('apple');
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INSERT INTO basic(name) VALUES ('banana');
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```
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SELECT subscription_name, status FROM pglogical.show_subscription_status();
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```
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>[!NOTE]
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>[!CAUTION]
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> Pglogical does not currently support an automatic DDL replication. The initial schema can be copied manually using pg_dump --schema-only. DDL statements can be executed on the provider and subscriber at the same time by using the pglogical.replicate_ddl_command function. Please be aware of other limitations of the extension listed [here](https://github.com/2ndQuadrant/pglogical#limitations-and-restrictions).
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‎articles/postgresql/flexible-server/concepts-read-replicas.md

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At the prompt, enter the password for the user account.
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[//]: # (## Monitor replication)
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## Monitor replication
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[//]: # ()
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[//]: # (Azure Database for PostgreSQL provides two metrics for monitoring replication. The two metrics are **Max Lag Across Replicas** and **Replica Lag**. To learn how to view these metrics, see the **Monitor a replica** section of the [read replica how-to article](how-to-read-replicas-portal.md).)
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[//]: # ()
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[//]: # (The **Max Lag Across Replicas** metric shows the lag in bytes between the primary and the most-lagging replica. This metric is applicable and available on the primary server only, and will be available only if at least one of the read replica is connected to the primary and the primary is in streaming replication mode. The lag information does not show details when the replica is in the process of catching up with the primary using the archived logs of the primary in a file-shipping replication mode.)
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[//]: # ()
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[//]: # (The **Replica Lag** metric shows the time since the last replayed transaction. If there are no transactions occurring on your primary server, the metric reflects this time lag. This metric is applicable and available for replica servers only. Replica Lag is calculated from the `pg_stat_wal_receiver` view:)
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[//]: # ()
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[//]: # (```SQL)
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[//]: # (SELECT EXTRACT (EPOCH FROM now() - pg_last_xact_replay_timestamp());)
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Azure Database for PostgreSQL - Flexible Server provides [two metrics](concepts-monitoring.md#replication) for monitoring replication. The two metrics are **Max Physical Replication Lag** and **Read Replica Lag**. To learn how to view these metrics, see the **Monitor a replica** section of the [read replica how-to article](how-to-read-replicas-portal.md#monitor-a-replica).
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[//]: # (```)
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The **Max Physical Replication Lag** metric shows the lag in bytes between the primary and the most-lagging replica. This metric is applicable and available on the primary server only, and will be available only if at least one of the read replicas is connected to the primary. The lag information is present also when the replica is in the process of catching up with the primary, during replica creation, or when replication becomes inactive. The lag information will not be available in case replication switches from using streaming replication to the archive recovery mode using archived files from primary.
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[//]: # ()
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[//]: # (Set an alert to inform you when the replica lag reaches a value that isn’t acceptable for your workload.)
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The **Read Replica Lag** metric shows the time since the last replayed transaction. For instance if there are no transactions occurring on your primary server, and the last transaction was replayed 5 seconds ago, then the Read Replica Lag will show 5 second delay. This metric is applicable and available on replicas only.
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[//]: # ()
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[//]: # (For additional insight, query the primary server directly to get the replication lag in bytes on all replicas.)
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Set an alert to inform you when the replica lag reaches a value that isn’t acceptable for your workload.
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[//]: # ()
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[//]: # (> [!NOTE])
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For additional insight, query the primary server directly to get the replication lag on all replicas.
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[//]: # (> If a primary server or read replica restarts, the time it takes to restart and catch up is reflected in the Replica Lag metric.)
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> [!NOTE]
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> If a primary server or read replica restarts, the time it takes to restart and catch up is reflected in the Replica Lag metric.
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## Promote replicas
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‎articles/postgresql/flexible-server/how-to-bulk-load-data.md

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Before you begin an initial data load on the flexible server, we recommend that you:
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- Disable high availability on the server. You can enable it after the initial load is completed on master/primary.
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- Disable high availability on the server. You can enable it after the initial load is completed on the primary.
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- Create read replicas after the initial data load is completed.
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- Make logging minimal or disable it altogether during initial data loads (for example: disable pgaudit, pg_stat_statements, query store).
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‎articles/postgresql/flexible-server/how-to-read-replicas-portal.md

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@@ -4,8 +4,8 @@ description: Learn how to manage read replicas Azure Database for PostgreSQL - F
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ms.service: postgresql
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ms.subservice: flexible-server
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ms.topic: how-to
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ms.author: srranga
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author: sr-msft
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ms.author: alkuchar
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author: AwdotiaRomanowna
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ms.date: 10/14/2022
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---
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:::image type="content" source="./media/how-to-read-replicas-portal/delete-confirm.png" alt-text="Confirm to delete te replica":::
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[//]: # (## Monitor a replica)
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## Monitor a replica
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[//]: # ()
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[//]: # (Two metrics are available to monitor read replicas.)
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Two metrics are available to monitor read replicas.
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[//]: # ()
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[//]: # (### Max Lag Across Replicas metric)
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### Max Physical Replication Lag
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> Available only on the primary.
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[//]: # ()
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[//]: # (The **Max Lag Across Replicas** metric shows the lag in bytes between the primary server and the most-lagging replica.)
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The **Max Physical Replication Lag** metric shows the lag in bytes between the primary server and the most-lagging replica.
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[//]: # ()
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[//]: # (1. In the Azure portal, select the primary Azure Database for PostgreSQL server.)
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1. In the Azure portal, select the primary server.
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[//]: # ()
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[//]: # (2. Select **Metrics**. In the **Metrics** window, select **Max Lag Across Replicas**.)
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2. Select **Metrics**. In the **Metrics** window, select **Max Physical Replication Lag**.
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[//]: # ()
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[//]: # ( :::image type="content" source="./media/how-to-read-replicas-portal/select-max-lag.png" alt-text="Monitor the max lag across replicas":::)
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:::image type="content" source="./media/how-to-read-replicas-portal/metrics_max_physical_replication_lag.png" alt-text="Screenshot of the Metrics blade showing Max Physical Replication Lag metric.":::
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:::image-end:::
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[//]: # (3. For your **Aggregation**, select **Max**.)
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3. For your **Aggregation**, select **Max**.
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[//]: # ()
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[//]: # (### Replica Lag metric)
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### Read Replica Lag metric
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> Available only on replicas.
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[//]: # ()
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[//]: # (The **Replica Lag** metric shows the time since the last replayed transaction on a replica. If there are no transactions occurring on your master, the metric reflects this time lag.)
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The **Read Replica Lag** metric shows the time since the last replayed transaction on a replica. If there are no transactions occurring on your primary, the metric reflects this time lag.
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[//]: # ()
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[//]: # (1. In the Azure portal, select the Azure Database for PostgreSQL read replica.)
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1. In the Azure portal, select read replica.
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[//]: # ()
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[//]: # (2. Select **Metrics**. In the **Metrics** window, select **Replica Lag**.)
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2. Select **Metrics**. In the **Metrics** window, select **Read Replica Lag**.
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[//]: # ( :::image type="content" source="./media/how-to-read-replicas-portal/select-replica-lag.png" alt-text="Monitor the replica lag":::)
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:::image type="content" source="./media/how-to-read-replicas-portal/metrics_read_replica_lag.png" alt-text=" screenshot of the Metrics blade showing Read Replica Lag metric.":::
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:::image-end:::
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[//]: # ()
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[//]: # (3. For your **Aggregation**, select **Max**.)
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3. For your **Aggregation**, select **Max**.
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## Next steps
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‎articles/postgresql/flexible-server/media/how-to-read-replicas-portal/metrics_max_physical_replication_lag.png

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‎articles/postgresql/flexible-server/media/how-to-read-replicas-portal/metrics_read_replica_lag.png

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‎articles/postgresql/single-server/how-to-read-replicas-cli.md

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ms.service: postgresql
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ms.subservice: single-server
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ms.topic: how-to
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ms.author: srranga
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ms.author: alkuchar
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author: AwdotiaRomanowna
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ms.date: 06/24/2022
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---
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The [az postgres server replica create](/cli/azure/postgres/server/replica#az-postgres-server-replica-create) command requires the following parameters:
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| Setting | Example value | Description |
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| --- | --- | --- |
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| resource-group | myresourcegroup | The resource group where the replica server will be created. |
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| name | mydemoserver-replica | The name of the new replica server that is created. |
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| source-server | mydemoserver | The name or resource ID of the existing primary server to replicate from. Use the resource ID if you want the replica and master's resource groups to be different. |
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| Setting | Example value | Description |
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| --- | --- |----------------------------------------------------------------------------------------------------------------------------------------------------------------------|
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| resource-group | myresourcegroup | The resource group where the replica server will be created. |
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| name | mydemoserver-replica | The name of the new replica server that is created. |
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| source-server | mydemoserver | The name or resource ID of the existing primary server to replicate from. Use the resource ID if you want the replica and primary's resource groups to be different. |
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In the CLI example below, the replica is created in the same region as the master.
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In the CLI example below, the replica is created in the same region as the primary.
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```azurecli-interactive
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az postgres server replica create --name mydemoserver-replica --source-server mydemoserver --resource-group myresourcegroup
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> Review the [considerations section of the Read Replica overview](concepts-read-replicas.md#considerations).
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> Before a primary server setting is updated to a new value, update the replica setting to an equal or greater value. This action helps the replica keep up with any changes made to the master.
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> Before a primary server setting is updated to a new value, update the replica setting to an equal or greater value. This action helps the replica keep up with any changes made to the primary.
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### List replicas
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If you haven't set the `azure.replication_support` parameter to **REPLICA** on a General Purpose or Memory Optimized primary server and restarted the server, you receive an error. Complete those two steps before you create a replica.
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A replica is created by using the same compute and storage settings as the master. After a replica is created, several settings can be changed independently from the primary server: compute generation, vCores, storage, and back-up retention period. The pricing tier can also be changed independently, except to or from the Basic tier.
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A replica is created by using the same compute and storage settings as the primary. After a replica is created, several settings can be changed independently from the primary server: compute generation, vCores, storage, and back-up retention period. The pricing tier can also be changed independently, except to or from the Basic tier.
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> Before a primary server setting is updated to a new value, update the replica setting to an equal or greater value. This action helps the replica keep up with any changes made to the master.
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> Before a primary server setting is updated to a new value, update the replica setting to an equal or greater value. This action helps the replica keep up with any changes made to the primary.
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### List replicas
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‎articles/postgresql/single-server/how-to-read-replicas-portal.md

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ms.author: alkuchar
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## Prepare the primary server
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1. In the Azure portal, select an existing Azure Database for PostgreSQL server to use as a primary.
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2. From the server's menu, select **Replication**. If Azure replication support is set to at least **Replica**, you can create read replicas.
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> Before a primary server setting is updated to a new value, update the replica setting to an equal or greater value. This action helps the replica keep up with any changes made to the primary.
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The **Replica Lag** metric shows the time since the last replayed transaction on a replica. If there are no transactions occurring on your primary, the metric reflects this time lag.
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‎articles/postgresql/single-server/how-to-read-replicas-powershell.md

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> values than the primary to ensure the replica is able to keep up with the primary.
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### List replicas for a primary server
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