Npgsql：如何准备语句 [英] Npgsql: How do Prepared Statements

问题描述

我们正在为多人游戏开发数据库后端。服务器使用C＃编写，并通过Npgsql与Postgres数据库进行对话。

we are developing a database backend for a multiplayer game. The server is written in C# and talks to a Postgres database via Npgsql.

现在，手册显示了如何使用准备好的语句：

Now, the manual shows how to use prepared statements:

NpgsqlCommand command = new NpgsqlCommand("select * from tablea where column1 = :column1", conn);
// Now add the parameter to the parameter collection of the command specifying its type.
command.Parameters.Add(new NpgsqlParameter("column1", NpgsqlDbType.Integer);
// Now, prepare the statement.
command.Prepare();
// Now, add a value to it and later execute the command as usual.
command.Parameters[0].Value = 4;

它表明准备好的语句仅在数据库会话中有效
我现在有两个问题：

And it states that prepared statements are valid only inside a database session. I have two questions now:

1。 ）如果我使用相同的命令文本和参数类型创建一个新的NpgsqlCommand对象，或者我必须保留该对象并在再次执行之前简单地更改变量，服务器是否会识别出该命令已准备就绪？在示例中，命令对象放置在查询之后。

1.) Will the server recognize that this command was prepared if I create a new NpgsqlCommand object with the same command text and parameter types or do I have to keep the object and simply change the variables before executing it again? In the example the command object is disposed after the query.

2。）虽然我们只有这种形式的简单语句，但准备好的语句可能会提高性能：

2.) Will prepared statements probably increase the performance although we ONLY have simple statements in this style:

SELECT f1,f2 FROM t1
UPDATE t1 SET f1=1, f2=2

有可能连续执行数百个具有相同样式的查询-当前正在创建一个新的NpgsqlCommand（以及NpgSql池中的NpgsqlConnection）

It is possible that hundreds of queries with the same style are executed in a row - currently creating a new NpgsqlCommand (and also NpgsqlConnection from NpgSql's pool) object for each query.

谢谢！

推荐答案

建议您不要使用准备好的语句。 Npgsql的性能还不是很好。 :(很抱歉。

I'd advise you to not use prepared statements. Npgsql doesn't have a very good performance yet with it. :( Sorry for that.

此外，为了发送大量插入命令，我认为您应该看看NpgsqlCopy支持。它将为您提供更好的性能
希望对您有所帮助。

also, in order to send a lot of insert commands, I think you should look at NpgsqlCopy support. It will give you a much better performance. I hope it helps.

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