PostgreSQL：存储功能中的dblink从本地到远程数据库 [英] Postgresql: dblink in Stored Functions from local to remote database

问题描述

我检查下面我使用并运行正常的链接。但是我想相反。

I check below link which I used and running perfectly. But I want to opposite this things.

Postgresql：存储函数中的dblink

我的情况：有两个数据库。我想将一个表数据从本地数据库复制到远程数据库。我为此使用了dblink，但我对如何使用dblink存储数据感到困惑？

My scenario: Two databases are there. I want to copy one table data from local to remote database. I used dblink for this used but I am confused how to use dblink to store the data?

本地数据库名称：localdatabase

Local database name: localdatabase

远程数据库名称：remotedatabase

Remote Database name: remotedatabase

有人可以建议我该怎么做吗？

Can any one suggest me how can I do this?

推荐答案

类似以下几行应该可以：

Something like the lines below should work:

SELECT dblink_connect('hostaddr=127.0.0.1 port=5432 dbname=mydb user=postgres password=mypasswd');
-- change the connection string to your taste

SELECT dblink_exec('INSERT INTO test (some_text) VALUES (''Text go here'');');

其中 test 是远程表具有以下定义的数据库：

Where test is a table in the remote database with the following definition:

CREATE TABLE test(
    id serial
    , some_text text
);

运行 dblink_exec（）后，可以检查远程数据库中的结果（或使用 dblink（）在本地，如下面的示例所示）。

After running dblink_exec(), you can check the results in the remote database (or locally, using dblink(), like in the example below).

SELECT * FROM dblink('SELECT id, some_text FROM test') AS d(id integer, some_text text);
 id |  some_text
----+--------------
  1 | Text go here
(1 row)

您可以包装 dblink_exec 还要调用函数：

You can wrap your dblink_exec call in a function as well:

CREATE OR REPLACE FUNCTION f_dblink_test_update(val text, id integer) RETURNS text AS
$body$
SELECT dblink_exec('UPDATE torles.test SET some_text=' || quote_literal($1) || ' WHERE id = ' || $2);
$body$
LANGUAGE sql;

您可以看到，甚至可以动态地构建查询字符串。 （不是我提倡这种方法，因为您必须小心，不要以这种方式将SQL注入漏洞引入您的系统。）

As you can see, you can even build your query string dynamically. (Not that I advocate this approach, since you have to be careful not to introduce a SQL injection vulnerability into your system this way.)

由于 dblink_exec 会返回一条有关其所做操作的文本消息，因此除非有以下说明，否则您必须将函数定义为 RETURNS text dblink_exec 调用之后的其他返回值的语句。

Since dblink_exec returns with a text message about what it did, you have to define your function as RETURNS text unless there are other value-returning statements after the dblink_exec call.

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