Oracle 数据库连接

嗨，团队，

我有一个关于使用SQL developer作为客户端连接到2节点RAC数据库的问题。
在 “sql开发人员连接” 对话框中，输入以下详细信息:-
a) 主机名
b) 服务名称

我了解使用service-name (而不是sid) 将客户端连接到任何实例节点，而客户端对此一无所知。
那么，主机名入口中的值指向哪个节点？
1) 它是否指向2个RAC实例节点中的任何一个？然后在这种情况下，服务名称不起作用，因为我们直接使用其主机名 (或ip) 连接到实例。
或者
2) 它是否指向数据库节点？
或者
3) 它是否指向某个将请求发送到2个RAC实例节点之一的负载平衡器节点？

如果我的理解是错误的，请纠正我。

谢谢

发现不一致的工作很不错，是的，我们不久前解决了这个问题。理想情况下，我们希望连接到整个集群的 “虚拟表示” 的东西，然后集群根据服务的定义和当前可用的节点等决定最好地发送该连接的位置。

为此，我们有一个叫做扫描的东西。这是MOS的摘录。

Grid Infrastructure Single Client Access Name (SCAN) Explained (Doc ID 887522.1)

In this Document
Purpose
Scope
Details
SCAN Concepts
Common Questions Regarding SCAN
How can we configure the SCAN and SCAN listener?
Do we still need to configure local listeners on each node?
How does SCAN work ?
Instead of DNS or GNS, Can we use '/etc/hosts' to resolve SCAN?
Can we use the previous method (Using VIP) for client connection?
Is it mandatory to use SCAN?
Is it supported to remove SCAN?
Is it recommended to use COST feature?
Demo
References
APPLIES TO:
Oracle Database Cloud Schema Service - Version N/A and later
Oracle Database Exadata Express Cloud Service - Version N/A and later
Oracle Database Exadata Cloud Machine - Version N/A and later
Oracle Cloud Infrastructure - Database Service - Version N/A and later
Oracle Database Backup Service - Version N/A and later
Information in this document applies to any platform.
PURPOSE
11gR2 Grid Infrastructure (CRS) introduced Single Client Access Name (SCAN) to simplify client access to database services, this article is going to explain whats SCAN and how it works.

SCOPE
Intended audience will be DBAs who is installing/upgrading to 11gR2 Grid Infrastructure or support analyst who is supporting stated product.

DETAILS
SCAN Concepts
Single client access name (SCAN) is the virtual hostname to provide for all clients connecting to the cluster (as opposed to the vip hostnames in 10g and 11gR1).
SCAN is a domain name registered to at least one and up to three IP addresses, either in the domain name service (DNS) or the Grid Naming Service (GNS).
By default, the name used as the SCAN is also the name of the cluster and must be globally unique throughout your enterprise. The default value for the SCAN is based on the local node name. SCAN name must be at least one character long and no more than 15 characters in length, must be alphanumeric - cannot begin with a numeral and may contain hyphens (-). If you require a SCAN that is longer than 15 characters, then select an Advanced installation.
For installation to succeed, the SCAN must resolve to at least one address.
SCAN VIP addresses must be on the same subnet as virtual IP addresses and public IP addresses.
Oracle strongly recommends that you do not configure SCAN VIP addresses in the hosts file. But if you use the hosts file to resolve SCAN name, you can have only one SCAN IP address.
If hosts file is used to resolve SCAN hostname, you will receive Cluster Verification Utility failure at end of installation (see Note: 887471.1 for more details)
For high availability and scalability, Oracle recommends that you configure the SCAN to use DNS Round Robin resolution to three addresses.
Because the SCAN is associated with the cluster as a whole, rather than to a particular node, the SCAN makes it possible to add or remove nodes from the cluster without needing to reconfigure clients. It also adds location independence for the databases, so that client configuration does not have to depend on which nodes are running a particular database.
Clients can continue to access the cluster in the same way as with previous releases, but Oracle recommends that clients accessing the cluster use the SCAN. Clients using the SCAN can also access the cluster using EZCONNECT.
Grid Infrastructure will start local listener LISTENER on all nodes to listen on local VIP, and SCAN listener LISTENER_SCAN1 (up to three cluster wide) to listen on SCAN VIP(s); 11gR2 database by default will set local_listener to local LISTENER, and remote_listener to SCAN listener.
SCAN listener will be running off GRID_HOME, and by default, in 11gR2 local listener will be running off GRID_HOME as well.
In 12c, SCAN supports multiple subnets in the cluster (one SCAN per subnet)

该注释和文档中还有很多内容，但是要回答您的问题-扫描是我们连接的方式，而不是指定物理主机名