emphasize proxy_heart_beat creation

doc/cetus-mysql-prepare.md

@@ -68,12 +68,14 @@ create database if not exists proxy_heart_beat;
 use proxy_heart_beat;       
 CREATE TABLE if not exists `tb_heartbeat` (
   `p_id` varchar(128) NOT NULL ,
-  `p_ts` timestamp(3) NOT NULL DEFAULT CURRENT_TIMESTAMP(3),
+  `p_ts` timestamp(6) NOT NULL DEFAULT CURRENT_TIMESTAMP(6),
   PRIMARY KEY (`p_id`)
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8;
 
 GRANT ALL ON `proxy_heart_beat`.* TO 'cetus_app'@'192.0.0.1';
 
+**注意：创建心跳表时p_ts精度必须到小数点后，否则会影响主从延迟检测的准确度**
+
 ## sharding版MySQL环境准备
 
 若使用sharding功能，则需要根据业务创建业务表，并进行分库设计,若开启主从延迟检测，请参考读写分离版本配置心跳库和心跳表。

doc/cetus-rw.md

@@ -20,7 +20,7 @@ Cetus 读写分离版将前端发来的读请求和写请求分别发送到不
 
     CREATE TABLE tb_heartbeat (
     p_id varchar(128) NOT NULL,
-    p_ts timestamp(3) NOT NULL DEFAULT CURRENT_TIMESTAMP(3),
+    p_ts timestamp(6) NOT NULL DEFAULT CURRENT_TIMESTAMP(6),
     PRIMARY KEY (p_id)
     ) ENGINE = InnoDB DEFAULT CHARSET = utf8;
 

scripts/sql/proxy_heart_beat.sql

@@ -7,7 +7,7 @@ SET FOREIGN_KEY_CHECKS = 0;
 DROP TABLE IF EXISTS `tb_heartbeat`;
 CREATE TABLE `tb_heartbeat` (
   `p_id` varchar(128) NOT NULL,
-  `p_ts` timestamp(3) NOT NULL DEFAULT CURRENT_TIMESTAMP(3),
+  `p_ts` timestamp(6) NOT NULL DEFAULT CURRENT_TIMESTAMP(6),
   PRIMARY KEY (`p_id`)
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8;
 

src/cetus-monitor.c

@@ -487,9 +487,9 @@ update_master_timestamp(int fd, short what, void *arg)
 
     /* Catch RW time 
      * Need a table to write from master and read from slave.
-     * CREATE TABLE `tb_heartbeat` (
+     * CREATE TABLE if not exists `tb_heartbeat` (
      *   `p_id` varchar(128) NOT NULL,
-     *   `p_ts` timestamp(3) NOT NULL DEFAULT CURRENT_TIMESTAMP(3),
+     *   `p_ts` timestamp(6) NOT NULL DEFAULT CURRENT_TIMESTAMP(6),
      *   PRIMARY KEY (`p_id`)
      * ) ENGINE = InnoDB DEFAULT CHARSET = utf8;
      */