Merge pull request #180 from yuanyl630/master

case-conversion featue document

Author: gaoxueyu

CN/modules/ROOT/nav.adoc

@@ -29,6 +29,8 @@
 **** xref:master/6.3.6.adoc[函数与存储过程]
 **** xref:master/6.3.7.adoc[嵌套子函数]
 **** xref:master/6.3.8.adoc[Force View]
+**** xref:master/6.3.9.adoc[大小写转换]
+*** xref:master/6.4.adoc[国标GB18030]
 *** 内置函数
 **** xref:master/6.4.1.adoc[sys_context]
 **** xref:master/6.4.2.adoc[userenv]

CN/modules/ROOT/pages/master/5.2.adoc

@@ -35,7 +35,7 @@ export PG_CONFIG=/usr/local/ivorysql/ivorysql-4/bin/pg_config
 
 ** 拉取pg_vector源码
 ```
-git clone --branch v0.6.2 https://github.com/pgvector/pgvector.git
+git clone --branch v0.8.1 https://github.com/pgvector/pgvector.git
 ```
 
 ** 安装 pgvector

CN/modules/ROOT/pages/master/6.3.9.adoc

@@ -0,0 +1,47 @@
+:sectnums:
+:sectnumlevels: 5
+
+:imagesdir: ./_images
+
+= 引用标识符大小写转换
+
+== 目的
+
+为了满足Oracle的引用标识符大小写兼容，ivorysql设计了三种引用标识符的大小写转换模式。
+
+== 实现说明
+
+如果在数据库初始化时附加了参数 `-C`，值可以为 `normal/interchange/lowercase`，则代码中 `Intidb.c->main()` 函数会处理该参数，根据参数值设置全局变量 `caseswitchmode`。然后 `initdb` 命令会以 `-boot` 模式启动一个 `psotgres` 进程用于设置 `template1` 模板数据库，同时赋予参数 `-C ivorysql.identifier_case_switch=caseswitchmode` 给新进程。
+
+这个新启动的后端进程会通过下面的代码将 `identifier_case_switch` 信息写入 `pg_control` 文件：
+
+```
+BootstrapModeMain() -> BootStrapXLOG();
+	/* save database compatible level value */
+	ControlFile->dbmode = bootstrap_database_mode;
+	ControlFile->casemode = identifier_case_switch;  		
+	
+	/* some additional ControlFile fields are set in WriteControlFile() */
+	WriteControlFile();
+```
+
+当用户使用 `pg_ctl` 命令启动数据库时，`postmaster` 进程会读取 `pg_control` 文件的内容，代码调用路径为：
+
+```
+PostmasterMain()-->SetCaseGucOption()-->GetCaseSwitchModeFromControl()
+```
+
+读取到参数值后调用 `SetConfigOption()` 函数进行赋值。
+
+在每个新的后端进程开始的时候，由于是从 `postmaster` 进程 `fork` 而来，会自动拥有相同的 `ivorysql.identifier_case_switch` 参数值。首先处理 `startup` 包，其中如果包含 `database` 或者 `user` 这两个参数，则根据 `identifier_case_switch` 对参数值做相应的处理。
+
+源代码为：
+
+```
+BackendMain()->BackendInitialize()-->ProcessStartupPacket()
+```
+
+另外，在处理用户的 SQL 语句时，如果包含标识符，也会进行同样的处理，代码分布在：
+SplitIdentifierString()，quoteOneName() 和 SplitGUCList() 这几个函数中。
+
+

EN/modules/ROOT/nav.adoc

@@ -28,6 +28,8 @@
 *** xref:master/6.3.6.adoc[Function and stored procedure]
 *** xref:master/6.3.7.adoc[Nested Subfunctions]
 *** xref:master/6.3.8.adoc[Force View]
+*** xref:master/6.3.9.adoc[Case Conversion]
+** xref:master/6.4.adoc[GB18030 Character Set]
 ** Built-in Functions
 *** xref:master/6.4.1.adoc[sys_context]
 *** xref:master/6.4.2.adoc[userenv]

EN/modules/ROOT/pages/master/6.3.9.adoc

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+:sectnums:
+:sectnumlevels: 5
+
+:imagesdir: ./_images
+
+= Quoted Identifier Case Conversion
+
+== Purpose
+
+To meet Oracle's quoted identifier case compatibility requirements, IvorySQL has designed three case conversion modes for quoted identifiers.
+
+== Implementation Details
+
+If the parameter `-C` is appended during database initialization, with values of `normal/interchange/lowercase`, the `Intidb.c->main()` function in the code will process this parameter and set the global variable `caseswitchmode` according to the parameter value. Then the `initdb` command will start a `postgres` process in `-boot` mode to set up the `template1` template database, while passing the parameter `-C ivorysql.identifier_case_switch=caseswitchmode` to the new process.
+
+This newly started backend process will write the `identifier_case_switch` information to the `pg_control` file through the following code:
+
+```
+BootstrapModeMain() -> BootStrapXLOG();
+	/* save database compatible level value */
+	ControlFile->dbmode = bootstrap_database_mode;
+	ControlFile->casemode = identifier_case_switch;  		
+	
+	/* some additional ControlFile fields are set in WriteControlFile() */
+	WriteControlFile();
+```
+
+When a user starts the database using the `pg_ctl` command, the `postmaster` process will read the contents of the `pg_control` file. The code call path is:
+
+```
+PostmasterMain()-->SetCaseGucOption()-->GetCaseSwitchModeFromControl()
+```
+
+After reading the parameter value, the `SetConfigOption()` function is called to assign the value.
+
+When each new backend process starts, since it is forked from the `postmaster` process, it automatically has the same `ivorysql.identifier_case_switch` parameter value. First, it processes the `startup` packet, and if it contains `database` or `user` parameters, the parameter values are processed accordingly based on `identifier_case_switch`.
+
+The source code is:
+
+```
+BackendMain()->BackendInitialize()-->ProcessStartupPacket()
+```
+
+Additionally, when processing user SQL statements, if they contain identifiers, the same processing is performed. The code is distributed in:
+SplitIdentifierString(), quoteOneName() and SplitGUCList() functions.
+
+
+