MySQLSchema设计（四）一个MySQL里的JQuery：common_schema(一)

我们总要在一定的框架中活着，框架的构成有来自法律，有来自道德的，还有来自潜规则的。大部分人只求安生的活着，玩命的人毕竟是少数，有人打破框架平度青云，也有人打破框却架坠落深渊。每每跟开发人员讨论业务，就会听到一大滩框架名称，觉得很是高上大的样子。但他山之石可以攻玉，在MySQL当中也是有框架，这便是我们要介绍的common_schema。高性能MySQL一书作者 Baron Schwartz曾如是说：The common_schema is to MySQL as JQuery is to java script。本节仅仅简单介绍Schema相关部分，毕竟common_schema实在太强悍太广博。

软件主页：code.google.com/p/common-schema软件安装：

[mysql@DataHacker ~]$ mysql -uroot -p < common_schema-2.2.sql
Enter password:
complete
- Base components: installed
- InnoDB Plugin components: installed
- Percona Server components: not installed
- TokuDB components: partial install: 1/2

Installation complete. Thank you for using common_schema!

mysql> select attribute_name,substr(attribute_value,1,50) from metadata;
+-------------------------------------+----------------------------------------------------+
| attribute_name                      | substr(attribute_value,1,50)                       |
+-------------------------------------+----------------------------------------------------+
| author                              | Shlomi Noach                                       |
| author_url                          | http://code.openark.org/blog/shlomi-noach          |
| base_components_installed           | 1                                                  |
| innodb_plugin_components_installed  | 1                                                  |
| install_mysql_version               | 5.6.12-log                                         |
| install_sql_mode                    | NO_AUTO_VALUE_ON_ZERO,STRICT_TRANS_TABLES,NO_ENGIN |
| install_success                     | 1                                                  |
| install_time                        | 2014-02-05 21:53:55                                |
| license                             |

common_schema - DBA's Framework for MySQL
Copyri |
| license_type                        | GPL                                                |
| percona_server_components_installed | 0                                                  |
| project_home                        | http://code.google.com/p/common-schema/            |
| project_name                        | common_schema                                      |
| project_repository                  | https://common-schema.googlecode.com/svn/trunk/    |
| project_repository_type             | svn                                                |
| revision                            | 523                                                |
| version                             | 2.2                                                |
+-------------------------------------+----------------------------------------------------+
17 rows in set (0.00 sec)

mysql> desc help_content;
+--------------+-------------+------+-----+---------+-------+
| Field        | Type        | Null | Key | Default | Extra |
+--------------+-------------+------+-----+---------+-------+
| topic        | varchar(32) | NO   | PRI | NULL    |       |
| help_message | text        | NO   |     | NULL    |       |
+--------------+-------------+------+-----+---------+-------+
2 rows in set (0.00 sec)

mysql> select topic from help_content;
+--------------------------------+
| topic                          |
+--------------------------------+
| auto_increment_columns         |
| candidate_keys                 |
| candidate_keys_recommended     |

mysql> select help_message from help_content where topic='innodb_index_stats'\G;
*************************** 1. row ***************************
help_message:
NAME

innodb_index_stats: Estimated InnoDB depth & split factor of key's B+ Tree

TYPE

View

DESCRIPTION

innodb_index_stats extends the INNODB_INDEX_STATS patch in Percona Server, and
presents with estimated depth & split factor of InnoDB keys.
Estimations are optimistic, in that they assume condensed trees. It is
possible that the depth is larger than estimated, and that split factor is
lower than estimated.
Estimated values are presented as floating point values, although in reality
these are integer types.
This view is experimental and in BETA stage.
This view depends upon the INNODB_INDEX_STATS patch in Percona Server.
Note that Percona Server 5.5.8-20.0 version introduced changes to the
INNODB_INDEX_STATS schema. This view is compatible with the new schema, and is
incompatible with older releases.
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