实体框架代码首先在生产中使用mysql

Question

I am creating an asp.net * MVC * application using EF code first. I had used Sql azure as my database. But it turns out Sql Azure is not reliable. So I am thinking of using MySql/PostgreSQL for database.

I wanted to know the repercussions/implications of using EF code first with MySql/PostgreSQL in regards of performance . Has anyone used this combo in production or knows anyone who has used it?

EDIT
I keep on getting following exceptions in Sql Azure .

SqlException: "*A transport-level error has occurred when receiving results from the server.* 
(provider: TCP Provider, error: 0 - An existing connection was forcibly closed by the remote host.)"

---

    SqlException: *"Database 'XXXXXXXXXXXXXXXX' on server 'XXXXXXXXXXXXXXXX' is not
 currently available. Please retry the connection later.* If the problem persists, contact
 customer support, and provide them the session tracing ID of '4acac87a-bfbe-4ab1-bbb6c-4b81fb315da'.
 Login failed for user 'XXXXXXXXXXXXXXXX'."

Answer 1

First your problem seems to be a network issue, perhaps with your ISP. You may want to look at getting a remote PostgreSQL or MySQL db I think you will run into the same problems.

Secondly comparing MySQL and PostgreSQL performance is relatively tricky. In general, MySQL is optimized for pkey lookups, and PostgreSQL is more generally optimized for complex use cases. This may be a bit low-level but....

MySQL InnoDB tables are basically btree indexes where the leaf note includes the table data. The primary key is the key of the index. If no primary key is provided, one will be created for you. This means two things:

1. select * from my_large_table will be slow as there is no support for a physical order scan.

2. Select * from my_large_table where secondary_index_value = 2 requires two index traversals sinc ethe secondary index an only refer to the primary key values.

In contrast a selection for a primary key value will be faster than on PostgreSQL because the index contains the data.

PostgreSQL by comparison stores information in an unordered way in a series of heap pages. The indexes are separate from the data. If you want to pull by primary key you scan the index, then read the data page in which the data is found, and then pull the data. In comparison, if you pull from a secondary index, this is not any slower. Additionally, the tables are structured such that sequential disk access is possible when doing a long select * from my_large_table will result in the operating system read-ahead cache being able to speed performance significantly.

In short, if your queries are simply joinless selection by primary key, then MySQL will give you better performance. If you have joins and such, PostgreSQL will do better.