增加新建column family操作-demo01

README.md

@@ -17,65 +17,65 @@ This extension is developed and maintained by the VidarDB team. Feel free to rep
 We test this foreign data wrapper on Ubuntu Server 18.04 using PostgreSQL-11 together with RocksDB-6.2.4 (built with GCC-7.4.0).
 
 - Install PostgreSQL and the dev library which is required by extensions:
-
+  
   ```sh
   # add the repository
   sudo tee /etc/apt/sources.list.d/pgdg.list << END
   deb http://apt.postgresql.org/pub/repos/apt/ bionic-pgdg main
   END
-
+  
   # get the signing key and import it
   wget https://www.postgresql.org/media/keys/ACCC4CF8.asc
   sudo apt-key add ACCC4CF8.asc
-
+  
   # fetch the metadata from the new repo
   sudo apt-get update
-
+  
   # install postgresql and the dev library
   sudo apt-get install postgresql-11
   sudo apt-get install postgresql-server-dev-11
   ```
 
 - Install [RocksDB](https://github.com/facebook/rocksdb) from source code:
-
+  
   ```sh
   git clone -b v6.2.4 https://github.com/facebook/rocksdb.git
-
+  
   cd rocksdb
-
+  
   sudo DEBUG_LEVEL=0 make shared_lib install-shared
 
   sudo sh -c "echo /usr/local/lib >> /etc/ld.so.conf"  
-
+  
   sudo ldconfig
   ```
 
 - Build this foreign data wrapper:
-
+  
   ```sh
   git clone git@github.com:postgrespro/lsm.git
-
+  
   cd lsm
-
+  
   make
-
+  
   sudo make install
   ```
 
 - Before using this foreign data wrapper, we need to add it to `shared_preload_libraries` in the `postgresql.conf`:
-
+  
   ```sh
   echo "shared_preload_libraries = 'lsm'" >> postgresql.conf
   ```
-
+  
   and restart PostgreSQL:
-
+  
   ```sh
   sudo service postgresql restart
   ```
 
 - When uninstall this extension, first issue the following commands, and then delete the data by locating PostgreSQL data folder via `show data_directory;` in PostgreSQL terminal.
-
+  
   ```sh
   cd PostgresForeignDataWrapper
 
@@ -98,7 +98,6 @@ This extension does not have any parameter. After creating the extension and cor
 
 A simple example is as follows (*you can run '`sudo -u postgres psql -U postgres`' to connect the local postgresql server*):
 
-
 ```
     CREATE DATABASE example;  
     \c example  
@@ -124,17 +123,15 @@ A simple example is as follows (*you can run '`sudo -u postgres psql -U postgres
 
     DROP SERVER lsm_server;  
     DROP EXTENSION lsm_fdw;  
-  
+
     \c postgres  
     DROP DATABASE example;  
-
-``` 
+```
 
 # Testing
 
 We have tested certain typical SQL statements and will add more test cases later. The test scripts are in the test/sql folder which are recommended to be placed in a non-root directory. The corresponding results can be found in the test/expected folder. You can run the tests in the following way:
 
-
 ```sh
     sudo service postgresql restart  
 
@@ -147,16 +144,15 @@ We have tested certain typical SQL statements and will add more test cases later
     sudo -u postgres psql -U postgres -d lsmtest -a -f test/sql/clear.sql  
 ```
 
-# Debug 
+# Debug
 
 If you want to debug the source code, you may need to start PostgreSQL in the debug mode:
 
-
 ```sh
     sudo service postgresql stop  
 
     sudo -u postgres /usr/lib/postgresql/11/bin/postgres -d 0 -D /var/lib/postgresql/11/main -c config_file=/etc/postgresql/11/main/postgresql.conf
-```  
+```
 
 # Docker
 

lsm_api.h

@@ -2,26 +2,27 @@
  * This file represents API between client working with Postgres API and C++ server working with RocksDB API.
  * To avoid collision between C/C++ headers they are sharing just this one header file.
  */
-#ifndef __LSM_API_H__
-#define __LSM_API_H__
+#ifndef __LSM_API_H__	// 如果没有定义这个宏
+#define __LSM_API_H__	// 就定义下面的宏
 
 #include <stddef.h>
 #include <stdint.h>
 #include <stdbool.h>
 
 #ifdef __cplusplus
-extern "C" {
+extern "C" {	//加上extern "C"后，会指示编译器这部分代码按C语言的进行编译，而不是C++的。
 #endif
 
 /*
  * Maximal size of record which can be transfered through client-server protocol and read batch size as well
  */
-#define LSM_MAX_RECORD_SIZE (64*1024)
+// 定义client 和 server之间传送的数据的最大数据量
+#define LSM_MAX_RECORD_SIZE (64*1024)	//64KB
 
 /*
  * Name of the directory in $PGDATA
  */
-#define LSM_FDW_NAME        "lsm"
+#define LSM_FDW_NAME        "lsm"	//定义fdw的名称为lsm
 
 extern int  LsmQueueSize;
 extern bool LsmSync;
@@ -42,6 +43,7 @@ typedef enum
 	LsmOpLookup
 } LsmOperation;
 
+// 定义client和server之间的各种操作
 extern void     LsmError(char const* message);
 extern size_t   LsmShmemSize(int maxClients);
 extern void     LsmInitialize(void* ctl, int maxClients);

lsm_client.cpp

@@ -57,15 +57,17 @@ LsmDelete(LsmQueueId qid, LsmRelationId rid, char *key, size_t keyLen)
 	return true;
 }
 
+
+// 将传入的数据以LsmMessage进行传输
 bool
 LsmInsert(LsmQueueId qid, LsmRelationId rid, char *key, size_t keyLen, char *val, size_t valLen)
 {
 	LsmMessage msg;
 	LsmQueue* queue = queues[qid];
 	msg.hdr.op = LsmOpInsert;
-	msg.hdr.rid = rid;
-	msg.hdr.keySize = keyLen;
-	msg.hdr.valueSize = valLen;
+	msg.hdr.rid = rid;	//外部表oid
+	msg.hdr.keySize = keyLen;	//key的长度
+	msg.hdr.valueSize = valLen;	//value的长度
 	msg.key = key;
 	msg.value = val;
 	queue->put(msg);
@@ -77,6 +79,8 @@ LsmInsert(LsmQueueId qid, LsmRelationId rid, char *key, size_t keyLen, char *val
 	return true;
 }
 
+
+
 uint64_t
 LsmCount(LsmQueueId qid, LsmRelationId rid)
 {

lsm_db.h

@@ -8,8 +8,13 @@
 
 using namespace rocksdb;
 
+/**
+ * 对Rocksdb的封装
+ * 
+ * /
+
 /*
- * Wrapper for RocksSB
+ * Wrapper for RocksDB
  */
 struct LsmConnection
 {
@@ -44,6 +49,7 @@ struct LsmMessageHeader
 /*
  * Protocol message
  */
+// 用于包装传输的数据
 struct LsmMessage
 {
 	LsmMessageHeader hdr;
@@ -54,8 +60,10 @@ struct LsmMessage
 /*
  * Queue for tranferring data between backend and LSM worker thread.
  */
+// 用于将数据传送到rocksdb中
 struct LsmQueue
 {
+	// ring buffer 环状缓冲区
 	volatile int   getPos;   // get position in ring buffer (updated only by consumer)
 	volatile int   putPos;   // put position in ring buffer (updated only by producer)
 	volatile int   respSize; // response size
@@ -84,11 +92,13 @@ struct LsmCursor
 
 struct LsmServer;
 
+
+// 主要封装了对lsm的操作，也就是lsmServer中的一个工作进程
 struct LsmWorker
 {
 	std::map<LsmCursorId, LsmCursor> cursors;
-	LsmServer* server;
-	LsmQueue*  queue;
+	LsmServer* server;	// 一个server有很多的worker
+	LsmQueue*  queue;	//一个worker对应一个queue
 	pthread_t  thread;
 
 	LsmWorker(LsmServer* s, LsmQueue* q) : server(s), queue(q) {}
@@ -150,6 +160,8 @@ class CriticalSection
 	}
 };
 
+
+// 此结构体包含了很多对rocksdb的操作，非常重要，是一个对于rocksdb封装的最大对象，包含了很多的LsmWorker
 struct LsmServer
 {
 	LsmWorker** workers;