2015-08-17 veryyoung
前几天做一个需求用到了sql in 子查询, 大概sql如下 SELECT * FROM table_a WHERE id IN (SELECT id FROM table_id_list) 执行时间150m,完全没法忍受 单独执行 SELECT id FROM table_id_list 秒查,只有七八行结果。 把查询结果写死在sql中 SELECT * FROM table_a WHERE id IN (1,2,3,4,5) 依然秒查 解决方案 再把ID列表select一次 SELECT * FROM table_a WHERE id IN (SELECT id from(SELECT id FROM table 继续阅读 »
2014-03-15 Kun Ren
In R, function may not be as special as it is in other programming languages; it is regarded as one of the many types and can be passed as an argument to some other function. The way we deal with other objects such list and data.frame definitely applies to function. Here is a simple example in which we define two funct 继续阅读 »
2016-11-07 Lingxian Kong
In 'Project'->'Compute'->'Overview' pannel of Horizon, a common user can see some OpenStack resources usage information in 'Limit Summary' table in pie chart. By default, that includes 'Instances', 'VCPUs', 'RAM', 'Floating IPs', 'Security Groups', 'Volumes' and 'Volume Storage'. Horizon will get usage of those resourc 继续阅读 »
2012-12-30 Klaus Ma
In a large cluster, some un-expected long running task hold back the job’s runtime sometimes. And those long running tasks are hard to locate in such a large cluster. Some ideas are shown here to help to locate those long running tasks. One of them will be implemented in the coming released of OGL. 继续阅读 »
2014-02-20 Kun Ren
People love dealing with well-structured data. It costs much less efforts than working with disorganized raw texts. In economic and financial research, we typically download data from open-access websites or authentication-required databases. These sources may provide data in multiple formats. For example, almost all 继续阅读 »
2015-01-30 derekchan
IE8在上傳圖片時會莫名其妙多出個框, [][1] 继续阅读 »
2011-06-01 Robert Zhang
What's OOP on earth? How to do it in Lua? And what's Lua Class Lib? Let's have an interesting tour to OOP in Lua. 继续阅读 »
2016-05-14 王财勇
我是个幸运的家伙,我一直在暗暗跟自己说,每一段人生的过往我都和一批快乐的小伙伴一起度过。临到毕业季,我还抓住了毕业的尾巴,来到杭州实习,在in这个温暖的大家庭一起和大家度过了最充实最美好的时光。 我还清楚地记得我刚来实习的那几天。自去年收到in的offer,我就准备抽时间来实习,本来想要在1月1日来实习,可是由于毕业论文的因素一直拖到了2月22日,到了要走的那一天,我挑了一些和图像处理相关的书以及一些衣服就坐上了到杭州的无座火车,当时没买到票,就凑合着和人家挤着坐着混混沌沌地来到了杭州。 来到杭州就联系了我的大学同学邹浩,我们叫“耗子”。耗子帮着我一起找了房子,找了一天的时间,累成狗了,主要我预计实习三个月,所以短租不好找,经过 继续阅读 »
2013-06-02 Klaus Ma
For the performance tuning, the simplest way is to record how many time is elapsed in a function. The only difficulty we’re facing is that: there maybe many exit for a function. Thanks to C++’s constructor/deconstructor feature, it’s easy for developer to record the elsaped time. 继续阅读 »
2015-12-14 Klaus Ma
Volumes in Docker The following command mounts volumes from host with uid/gid: docker run -i -t -v $HOME/test:/opt/test -u=10:10 ubuntu 继续阅读 »