正文
go语言访问mycat go语言访问map中struct的key
提示：扫一扫查出行【扫一扫了解最新限行尾号】
复制提示
英语短文50字my cat有翻译
nd lay around it every day. He climbed to the tree top, ate the apples, took a nap under the shadow... He loved the tree and the tree loved to play with him. 很久很久以前,有一棵又高又大go语言访问mycat的苹果树.一位小男孩,天天到树下来,他爬上去摘苹果吃,在树荫下睡觉.他爱苹果树,苹果树也爱和他一起玩耍. Time went by... the little boy had grown up and he no longer played around the tree every day. One day, the boy came back to the tree and he looked sad. “Come and play with me,” the tree asked the boy. “I am no longer a kid, I don’t play around trees anymore.” The boy replied, “I want toys. I need money to buy them.”“Sorry, but I don’t have money...but you can pick all my apples and sell them. So, you will have money.” The boy was so excited. He grabbed all the apples on the tree and left happily. The boy never came back after he picked the apples. The tree was sad. 后来,小男孩长大了,不再天天来玩耍.一天他又来到树下,很伤心go语言访问mycat的样子.苹果树要和他一起玩,男孩说：“不行,我不小了,不能再和你玩,我要玩具,可是没钱买.”苹果树说：“很遗憾,我也没钱,不过,把我所有go语言访问mycat的果子摘下来卖掉,你不就有钱了?”男孩十分激动,他摘下所有的苹果,高高兴兴地走了.然后,男孩好久都没有来.苹果树很伤心.
相关问答
Q1: c++能访问mycat的吗
可以，访问内容非常简单，仅需要我们将原MySQL的连接信息替换为MyCat的连接信息即可。
扩展：从定义和分类来看，它是一个开源的分布式数据库系统，是一个实现了MySQL协议的服务器，前端用户可以把它看作是一个数据库代理，用MySQL客户端工具和命令行访问，而其后端可以用MySQL原生协议与多个MySQL服务器通信，也可以用JDBC协议与大多数主流数据库服务器通信，其核心功能是分表分库，即将一个大表水平分割为N个小表，存储在后端MySQL服务器里或者其他数据库里。
Q2: 英语作文my cat
My Cat
I have a white cat. It is a present from my mother on my birthday. It’s very beautiful. I call it Mimi.
Mimi is very naughty. She likes to play with me. She often runs here and there and likes running after something. Mimi’s favourite game is playing with balls, ropes and stones. I love it very much. Sometimes, Mimi is very gentle. She likes to wash her face and doesn’t play with me. After lunch, Mimi often lies on the sofa to sleep. When I go home, Mimi often jumps onto my knees. I like to give a bath to Mimi.
Oh, my baby cat brings me much happiness. We are good friends. I love Mimi.
Q3: mycat常用后端管理命令
mycat常用后端管理命令
首先通过show @@helap; 就可以大致的了解Mycat 管理端口的常用命令(dbserver.xml配置)！
mysql show @@help;
+------------------------------------------+--------------------------------------------+
| STATEMENT | DESCRIPTION |
+------------------------------------------+--------------------------------------------+
| show @@time.current | Report current timestamp |
| show @@time.startup | Report startup timestamp |
| show @@version | Report Mycat Server version |
| show @@server | Report server status |
| show @@threadpool | Report threadPool status |
| show @@database | Report databases |
| show @@datanode | Report dataNodes |
| show @@datanode where schema = ? | ReportdataNodes |
| show @@datasource | Report dataSources |
| show @@datasource where dataNode = ? | Report dataSources |
| show @@datasource.synstatus |Report datasource data synchronous |
| show @@datasource.syndetail where name=? | Report datasource data synchronousdetail |
| show @@datasource.cluster | Report datasource galary cluster variables |
| show @@processor | Report processor status |
| show @@command | Report commands status |
| show @@connection | Report connection status |
| show @@cache | Report system cache usage |
| show @@backend | Report backend connection status |
| show @@session | Report front session details |
| show @@connection.sql | Report connection sql |
| show @@sql.execute | Report execute status |
| show @@sql.detail where id = ? | Reportexecute detail status |
| show @@sql | Report SQL list |
| show @@sql.high | Report Hight Frequency SQL |
| show @@sql.slow | Report slow SQL |
| show @@sql.resultset | Report BIG RESULTSET SQL |
| show @@sql.sum | Report User RW Stat |
| show @@sql.sum.user | Report User RW Stat |
| show @@sql.sum.table | Report Table RW Stat |
| show @@parser | Report parser status |
| show @@router | Report router status |
| show @@heartbeat | Report heartbeat status |
| show @@heartbeat.detail where name=? | Report heartbeat currentdetail |
| show @@slow where schema = ? |Report schema slow sql |
| show @@slow where datanode = ? | Reportdatanode slow sql |
| show @@sysparam | Report system param |
| show @@syslog limit=? | Report system mycat.log |
| show @@white | show mycat white host |
| show @@white.set=?,? | set mycat white host,[ip,user] |
| show @@directmemory=1 or 2 |show mycat direct memory usage |
| switch @@datasource name:index | SwitchdataSource |
| kill @@connection id1,id2,... | Killthe specified connections |
| stop @@heartbeat name:time |Pause dataNode heartbeat |
| reload @@config | Reload basic config from file |
| reload @@config_all | Reload all config from file |
| reload @@route | Reload route config from file |
| reload @@user | Reload user config from file |
| reload @@sqlslow= | Set Slow SQL Time(ms) |
| reload @@user_stat | Reset show @@sql @@sql.sum @@sql.slow |
| rollback @@config | Rollback all config from memory |
| rollback @@route | Rollback route config from memory |
| rollback @@user | Rollback user config from memory |
| reload @@sqlstat=open | Open real-time sql stat analyzer |
| reload @@sqlstat=close | Close real-time sql stat analyzer |
| offline | Change MyCat status to OFF |
| online | Change MyCat status to ON |
| clear @@slow where schema = ? |Clear slow sql by schema |
| clear @@slow where datanode = ? | Clearslow sql by datanode |
+------------------------------------------+--------------------------------------------+
58 rows in set (0.00 sec)
1、连接mycat 9066管理端口
命令：mysql -uusername -ppasswd -P9066 -hIP
-u:用户名
-p:密码
-P:端口
-h:ip地址例：linux路径切换到mycat安装路径的bin目录中：输入命令
显示如此则登录成功。
2、显示后端物理库连接信息，包括当前连接数，端口等信息。
命令：Show @@backend
3、显示当前前端客户端连接情况
命令：Show @@connection
4、当前线程池的执行情况，是否有积压(active_count)以及task_queue_size，后者为积压的待处理的SQL，若积压数目一直保值，
则说明后端物理连接可能不够或者SQL执行比较缓慢
命令：show @@threadpool;
5、当前后端物理库的心跳检测情况,RS_CODE为1表示心跳正常
命令：show @@heartbeat;
6、显示数据节点的访问情况，包括每个数据节点当前活动连接数(active),空闲连接数（idle）以及最大连接数(maxCon) size，EXECUTE参数表示从该节点获取连接的次数，
次数越多，说明访问该节点越多
命令：show @@datanode;
6、显示当前processors的处理情况，包括每个processor的IO吞吐量(NET_IN/NET_OUT)、IO队列的积压情况(R_QUEY/W_QUEUE)，Socket Buffer Pool的使用情况
BU_PERCENT为已使用的百分比、BU_WARNS为Socket Buffer Pool不够时，临时创建的新的BUFFER的次数，若百分比经常超过90%并且BU_WARNS0，则表明BUFFER
不够，需要增大，参见性能调优手册。
命令：show @@processor;
7、显示缓存的使用情况，对于性能监控和调优很有价值
命令：show @@cache;
MAX为缓存的最大值（记录个数），CUR为当前已经在缓存中的数量，ACESS为缓存读次数，HIT为缓存命中次数，PUT 为写缓存次数，LAST_XX为最后操作时间戳，比较重要的几个参数：CUR：若CUR接近MAX，而PUT大于MAX很多，则表明MAX需要增大，HIT/ACCESS为缓存命中率，这个值越高越好。
8、杀掉客户端的连接，参数为连接的ID值，通过show @@connection，可以展示当前连接到MyCAT的所有客户端进程，若某个进程异常，则可以通过该命令杀掉连接，如 KILL @@CONNECTION26907;
9、重新加载配置文件schema.xml
如果我们在原有的schema.xml中进行了修改，需要重新加载该文件使其生效。
命令：reload @@config;
Q4: go语言如何调用c函数
直接嵌入c源代码到go代码里面
package main
/*
#include stdio.h
void myhello(int i) {
printf("Hello C: %d\n", i);
}
*/
import "C"
import "fmt"
func main() {
C.myhello(C.int(12))
fmt.Println("Hello Go");
}
需要注意的是C代码必须放在注释里面
import "C"语句和前面的C代码之间不能有空行
运行结果
$ go build main.go ./main
Hello C: 12
Hello Go
分开c代码到单独文件
嵌在一起代码结构不是很好看，很多人包括我，还是喜欢把两个分开，放在不同的文件里面，显得干净，go源文件里面是go的源代码，c源文件里面是c的源代码。
$ ls
hello.c hello.h main.go
$ cat hello.h
void hello(int);
$ cat hello.c
#include stdio.h
void hello(int i) {
printf("Hello C: %d\n", i);
}
$ cat main.go
package main
// #include "hello.h"
import "C"
import "fmt"
func main() {
C.hello(C.int(12))
fmt.Println("Hello Go");
}
编译运行
$ go build ./main
Hello C: 12
Hello Go
编译成库文件
如果c文件比较多，最好还是能够编译成一个独立的库文件，然后go来调用库。
$ find mylib main
mylib
mylib/hello.h
mylib/hello.c
main
main/main.go
编译库文件
$ cd mylib
# gcc -fPIC -shared -o libhello.so hello.c
编译go程序
$ cd main
$ cat main.go
package main
// #cgo CFLAGS: -I../mylib
// #cgo LDFLAGS: -L../mylib -lhello
// #include "hello.h"
import "C"
import "fmt"
func main() {
C.hello(C.int(12))
fmt.Println("Hello Go");
}
$ go build main.go
运行
$ export LD_LIBRARY_PATH=../mylib
$ ./main
Hello C: 12
Hello Go
在我们的例子中，库文件是编译成动态库的，main程序链接的时候也是采用的动态库
$ ldd main
linux-vdso.so.1 = (0x00007fffc7968000)
libhello.so = ../mylib/libhello.so (0x00007f513684c000)
libpthread.so.0 = /lib64/libpthread.so.0 (0x00007f5136614000)
libc.so.6 = /lib64/libc.so.6 (0x00007f5136253000)
/lib64/ld-linux-x86-64.so.2 (0x000055d819227000)
理论上讲也是可以编译成整个一静态链接的可执行程序，由于我的机器上缺少静态链接的系统库，比如libc.a，所以只能编译成动态链接。
关于go语言访问mycat和go语言访问map中struct的key的介绍到此就结束了，不知道你从中找到你需要的信息了吗 ？如果你还想了解更多这方面的信息，记得收藏关注本站。
