SEARCH KEYWORD -- ORACLE DATABASE


  How to optimize MySQL insert statement

For a big data system, one problem is the data access efficiency, one more problem is that the data insertion is very slow. We had a service system, the data loading process would take 4-5 hours. This time consuming operation is risky since if the program is interrupted during the loading process, it might be rerun, this will be troublesome. So it's necessary to improve the insertion efficiency for big data systems. Here we provide two optimization suggestions. 1. Combine multiple insert stateme...

   MySQL,insert,optimization     2012-10-24 22:03:13

  Select top 3 values from each group in a table with SQL

Yesterday, my friend Liu Bing asked me a question about how to select top 3 values for each person in a database table using SQL. I think this question is interesting and it deserves some thoughts. Here I record down how to solve this issue. Assume we have a table which has two columns, one column contains the names of some people and the other column contains some values related to each person. One person can have more than one value. Each value has a numeric type. The question is we want to se...

   SQL,Correlated query,top 3     2013-05-23 03:21:25

  Set file permission in Java

Prior to Java 6,  there is no good solution at the Java level to provide file permission management. You need to implement your own native methods or call the Runtime.exec() to invoke the system routine such as chmod in LInux. Since Java 6, Java introduces a set of methods which can be used to set the file permission at Java level. These methods include: File.setReadable(boolean); File.setWritable(boolean); FIle.setExecutable(boolean); File.setReadable(boolean, boolean); File.setWritable(bo...

   JAVA, FILE PERMISSION, POSIX,learnjava     2015-08-29 03:37:37

  Tips for a better first-time hackathon experience

Here are a few things you can consider. These are by no means the only way to go about hackathons, just what's worked for me.ProjectI strongly strongly recommend doing something you haven't done before. Even if you're going into a hackathon with the intention of winning, trying something new is always fun and will keep you engaged throughout the event. Jump into mobile development, try hardware hacking, write a compiler, whatever; it's always fun to try out new things.Sticking to things you're c...

   hackathon     2014-03-31 07:25:09

  Why cannot compare double values directly for equality?

A question in PHP: Get some value from the database and use floatval() to convert it to floatint point value, then compare it with another value which is also converted to floating point value with floatval(). These two values are the same when using var_dump() to output, the two outputs are float(8.87), they are the same. But when comparing them for equality, the result is weird., they are not equal. Why?To analyze this question, we need to start with PHP data types. PHP uses weak types. In PHP...

   PHP,floating, precision,compare,equality     2012-06-27 09:01:36

  Why is single threaded Redis so fast

Redis is a high-performance, in-memory key-value database. According to official test reports, it can support around 100,000 QPS (queries per second) on a single machine. However, Redis uses a single-threaded architecture in its design. Why does Redis still have such high performance with a single-threaded design? Wouldn't it be better to use multiple threads for concurrent request processing? In this article, let's explore why Redis has a single-threaded architecture and still maintains its spe...

   REDIS,SINGLE-THREADED,MULTI-THREADING     2023-02-28 05:16:22

  Java Interview Questions

Currently there are many articles online which summarize the list of Java interview questions. Some cover lots of basic questions and some cover some specific questions in specific area such as multithreading. In this post, we will not cover the really basic questions, we will cover something different. For basic question, you can read Java Interview Questions。 Basic What is primitive data type? How many primitive data types in Java? What are they? -- A primitive type is prede...

   JAVA,SECURITY,INTERVIEW,CAREER,MULTITHREADING,QUESTION,JAVA INTERVIEW,JAVA CORE     2019-01-21 07:07:08

  Use of Erlang in WhatsApp

After many years, people are still discussing whether Erlang is a small language. People have all sorts of doubt about it, but with the appearance of WhatsApp, we may change our mind. What is WhatsApp, from its official website: WhatsApp Messenger is a cross-platform mobile messaging app which allows you to exchange messages without having to pay for SMS. The more funny thing is the main developer of WhatsApp Rick Reed worked in Yahoo and SGI before he joined WhatsApp and he didn't have any know...

   Erlang,WhatsApp,Architecture     2013-06-16 03:03:46

  All I Know About Certificates -- Websites

In last article, we know the role of clients and their responsibilities for certificate verification. Finally, let's talk about websites. We've discussed many potential issues between CAs and clients concerning certificates, but the most frequent issue is with websites—many websites have faced this problem: certificate expiration. Websites need to ensure two things: Ensure their certificate does not expire. Protect their private key from being leaked. If someone else obtains the priv...

   CLIENTS,WEBSITES,SSL CERTIFICATE,CERTIFICATE AUTHORITY,CA     2024-07-26 22:33:29

  Beauty of code : How to write graceful PHP code

Writing good code is an art. In order to achieve this, it is necessary to develop good programming habits at the beginning. Good programming habits not only contributes to the early project design (modular),but also allows you to the code easier to understand, so that the maintenance of the code is easier. Bad programming habits will result in more code bugs, and will make future maintenance work difficult. We introduce some good programming habits taking PHP as example. Hope this will help you....

   PHP,Good code     2012-08-26 12:23:03

RECENT