什么是数据库池？ [英] What is database pooling?
问题描述
我只是想知道数据库池的概念。如何实现。
I just wanted to know the concept of database pooling.How it is achieved.
推荐答案
/ em> pooling是一种用于保持数据库连接打开以便他人可以重用的方法。
Database connection pooling is a method used to keep database connections open so they can be reused by others.
通常，打开数据库连接是一种昂贵的操作，连接处于活动状态，以便在稍后请求连接时，使用活动连接之一优先打开另一个。
Typically, opening a database connection is an expensive operation, so pooling keeps the connections active so that, when a connection is later requested, one of the active ones is used in preference to opening another one.
在其最简单的形式中，它只是一个类似于对实际开放连接API的API调用，其首先检查池以获得合适的连接。如果一个可用，那就是给客户端，否则创建一个新的。
In it's simplest form, it's just a similar API call to the real open-connection API which first checks the pool for a suitable connection. If one is available, that's given to the client, otherwise a new one is created.
同样，有一个关闭的API调用，实际上不调用真实的关闭连接，而是将连接放入池中供以后使用。
Similarly, there's a close API call which doesn't actually call the real close-connection, rather it puts the connection into the pool for later use.
这是一个非常简单的解释。实际的实现可能能够处理到多个服务器的连接，可以预先分配一些连接的基线，使得一些基本连接立即就绪，当使用模式静音时实际上可以关闭旧连接，等等。
That's a pretty simplistic explanation. Real implementations may be able to handle connections to multiple servers, may pre-allocate some baseline of connections so some are ready immediately, may actually close old connections when the usage pattern quietens down, and so on.
所以，像下面这样：
+---------+
| |
| Clients |
+---------+ |
| |-+ +------+ +----------+
| Clients | ===#===> | Open | =======> | RealOpen |
| | | +------+ +----------+
+---------+ | ^
| |
| /------\
| | Pool |
| \------/
| ^
| |
| +-------+ +-----------+
#===> | Close | ======> | RealClose |
+-------+ +-----------+
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