cookqq博客的列表

cookqq ›博客列表

Replica Set Members 副本集成员介绍: Primary. 主副本 The primary receives all write operations. 提供所有写操作 Secondaries. 次副本 Secondaries replicate operations from the primary to maintain an identical data set. Secondaries may have additional configurations for special usage profiles. For example, secondaries may be non-voting orpriority 0. You can also maintain 保持 an arbiter as part of a replica set. Arbiters do not keep a copy of the data . However, arbiters play a role in the elections that select a primary if the current primary is unavailable. Arbiters 不保持数据，当主副本不能工作时候，Arbiters 作为选举（主副本）角色

Mongo Replication Introduction副本集介绍: Replication provides redundancy and increases data availability. With multiple copies of data on different database servers, replication protects a database from the loss of a single server. Replication also allows you to recover from hardware failure and service interruptions. With additional copies of the data, you can dedicate one to disaster recovery, reporting, or backup.随着数据的附加副本，您可以将一个灾难恢复

如何配置 MongoDB 副本集: 副本集的最常见配置需要一个主节点以及多个副节点。这之后启动的复制行为会从这个主节点到其他副节点。副本集不止可以针对意外的硬件故障和停机事件对数据库提供保护，同时也因为提供了更多的节点从而提高了数据库客户端数据读取的吞吐量。

Install MongoDB2.6.9 on Debian: Use this tutorial to install MongoDB from .deb packages on the current stable Debian release. While Debian includes its own MongoDB packages, the official MongoDB packages are more up to date.

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.: The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.，发现登陆用户、密码正确，连接池正确，mysql运行正确。最后把localhost修改成127.0.0.1即jdbc:mysql://127.0.0.1:3306/cookqq 为什么呢？？？看看下面分析

tomcat6解决too many open files: 网上普遍解决方法：（1）ulimit -n 2048 当前用户的最大允许打开文件数量设置为2048 （2）在 /etc/security/limits.conf 但是上面的方法设置open files失败，tomcat还是会报错too many open files 正确的方法是：（1）打开/etc/init.d/tomcat文件（2）在start命令后面增加

程序异常慢-撞见鬼了--too many open files: too many open files（1）远程备份的时候占用了大量open files，导致tomcat那边不够用了（2）备份占用了大量open files导致activeMQ生产者和消费者一直获取不到文件，导致一直释放不了锁，大量请求都堆积到一起（3）备份的文件量比较大，是局域网网络占满，导致外网请求堵塞。

nginx禁止某一个ip访问和非请请求: 什么.asp,php等请求，这些本系统都没有，明显是非法请求，查询漏洞的非法请求。解决办法：1、禁止掉183.60.244.30。（1）在/etc/nginx/conf.d创建blocksip.conf文件（2）在blocksip.conf文件中禁止掉183.60.244.30

Ubuntu 报too many open files错误解决方案(转): java.net.SocketException: Too many open files，这是因为网络请求过多，也就导致了系统打开的文件过多。每一个连接都会当成“文件”看待的。

mongodb分组group查询: 要实现MongoDB的分组查询，key（分组字段）、cond（分组条件）、refuce(分组计算方式)、initial(初始条件)是MongoDB分组查询比不可少的值。MongoVUE下如何实现MongoDB的分组查询功

mongodb开启慢查询日志: 　调用db.setProfilingLevel(级别) 命令来实时配置。可以通过db.getProfilingLevel()命令来获取当前的Profile级别。

ERROR: The partition with /var/lib/mysql is too full! failed!: ERROR: The partition with /var/lib/mysql is too full! failed!是分区的时候这个分区比较小，现在使用满了。那就修改mysql数据的存储路径吧

mongodb线程池解析和查询优化: mongodb查询query方法要慎用。如果想要查询一个表的所有数据请用cur.iterator()方法。慎用cur.toArray()，这个方法把所有的数据都放到内存中，如果数据量很大，你想想会出现什么情况。 cur.length()同样慎用，这个原因和cur.toArray()一样，也会把所有数据读到内存中，然后得到list大小。 cur.size()同样是获取cur这个游标大小，但是他的原理是再次执行一次查询数据库得到大小

hadoop 网站日志分析: PV(PageView): 页面访问量统计 IP: 页面独立IP的访问量统计 Time: 用户每小时PV的统计 Source: 用户来源域名的统计 Browser: 用户的访问设备统计

MongoDB Driver Quick Tour: To retrieve all the documents in the collection, we will use the find() method. The find() method returns a FindIterable instance that provides a fluent interface for chaining or controlling find operations. Use the iterator() method to get an iterator over the set of documents that matched the query and iterate. The following code retrieves all documents in the collection and prints them out (101 documents):

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