RDS Proxy 命令列範例

若要查看連線命令和 SQL 陳述式的組合如何與 RDS Proxy 互動，請參閱下列範例。

範例

• Preserving Connections to a MySQL Database Across a Failover

• Adjusting the max_connections Setting for an Aurora DB Cluster

範例

透過容錯移轉保留與 MySQL 資料庫的連線

此 MySQL 範例將示範已開啟的連線如何在容錯移轉期間繼續運作。例如，當您重新啟動資料庫，或資料庫因由於有問題而無法使用時。本範例使用一個名為 the-proxy 的代理，以及一個具有資料庫執行個體 instance-8898 和 instance-9814 的 Aurora 資料庫叢集。從 Linux failover-db-cluster 命令列執行命令時，代理連線的寫入器執行個體會變更為不同的資料庫執行個體。您可以看到與代理關聯的資料庫執行個體改變了，但連線仍然保持開啟。

$ mysql -h the-proxy.proxy-demo.us-east-1.rds.amazonaws.com -u admin_user -p
Enter password:
...

mysql> select @@aurora_server_id;
+--------------------+
| @@aurora_server_id |
+--------------------+
| instance-9814      |
+--------------------+
1 row in set (0.01 sec)

mysql>
[1]+  Stopped                 mysql -h the-proxy.proxy-demo.us-east-1.rds.amazonaws.com -u admin_user -p
$ # Initially, instance-9814 is the writer.
$ aws rds failover-db-cluster --db-cluster-identifier cluster-56-2019-11-14-1399
JSON output
$ # After a short time, the console shows that the failover operation is complete.
$ # Now instance-8898 is the writer.
$ fg
mysql -h the-proxy.proxy-demo.us.us-east-1.rds.amazonaws.com -u admin_user -p

mysql> select @@aurora_server_id;
+--------------------+
| @@aurora_server_id |
+--------------------+
| instance-8898      |
+--------------------+
1 row in set (0.01 sec)

mysql>
[1]+  Stopped                 mysql -h the-proxy.proxy-demo.us-east-1.rds.amazonaws.com -u admin_user -p
$ aws rds failover-db-cluster --db-cluster-identifier cluster-56-2019-11-14-1399
JSON output
$ # After a short time, the console shows that the failover operation is complete.
$ # Now instance-9814 is the writer again.
$ fg
mysql -h the-proxy.proxy-demo.us-east-1.rds.amazonaws.com -u admin_user -p

mysql> select @@aurora_server_id;
+--------------------+
| @@aurora_server_id |
+--------------------+
| instance-9814      |
+--------------------+
1 row in set (0.01 sec)
+---------------+---------------+
| Variable_name | Value         |
+---------------+---------------+
| hostname      | ip-10-1-3-178 |
+---------------+---------------+
1 row in set (0.02 sec)

範例

調整 Aurora 資料庫叢集的 max_connections 設定

此範例示範如何調整 Aurora MySQL 資料庫叢集的 max_connections 設定。若要這麼做，請根據 MySQL 5.7 相容叢集的預設參數設定，建立自己的資料庫叢集參數群組。您可以為 max_connections 設定指定一個值，以取代設定預設值的公式。將該資料庫叢集參數群組與資料庫叢集相關聯。

export REGION=us-east-1
export CLUSTER_PARAM_GROUP=rds-proxy-mysql-57-max-connections-demo
export CLUSTER_NAME=rds-proxy-mysql-57

aws rds create-db-parameter-group --region $REGION \
  --db-parameter-group-family aurora-mysql5.7 \
  --db-parameter-group-name $CLUSTER_PARAM_GROUP \
  --description "Aurora MySQL 5.7 cluster parameter group for RDS Proxy demo."

aws rds modify-db-cluster --region $REGION \
  --db-cluster-identifier $CLUSTER_NAME \
  --db-cluster-parameter-group-name $CLUSTER_PARAM_GROUP

echo "New cluster param group is assigned to cluster:"
aws rds describe-db-clusters --region $REGION \
  --db-cluster-identifier $CLUSTER_NAME \
  --query '*[*].{DBClusterParameterGroup:DBClusterParameterGroup}'

echo "Current value for max_connections:"
aws rds describe-db-cluster-parameters --region $REGION \
  --db-cluster-parameter-group-name $CLUSTER_PARAM_GROUP \
  --query '*[*].{ParameterName:ParameterName,ParameterValue:ParameterValue}' \
  --output text | grep "^max_connections"

echo -n "Enter number for max_connections setting: "
read answer

aws rds modify-db-cluster-parameter-group --region $REGION --db-cluster-parameter-group-name $CLUSTER_PARAM_GROUP \
  --parameters "ParameterName=max_connections,ParameterValue=$$answer,ApplyMethod=immediate"

echo "Updated value for max_connections:"
aws rds describe-db-cluster-parameters --region $REGION \
  --db-cluster-parameter-group-name $CLUSTER_PARAM_GROUP \
  --query '*[*].{ParameterName:ParameterName,ParameterValue:ParameterValue}' \
  --output text | grep "^max_connections"