SEARCH KEYWORD -- Key-base cache


  What is cache penetration, cache breakdown and cache avalanche?

When designing and developing highly available system, cache is an very important consideration. It is useful to cache some frequently accessed data so that they can be accessed quickly and also cache can protect the downstream system like DB from being hit too often.  To provide better cache design in large systems, some problems may need to be considered first. In this post, we will talk about some frequently discussed cache problems and mitigation plans. Cache penetration Cache penetrati...

   SYSTEM DESIGN,CACHE PENETRATION,CACHE BREAKDOWN,CACHE AVALANCHE     2020-04-10 08:43:00

  Why MySQL 8 drops support of query cache

Many of you may have heard or used MySQL's query cache, because it used to be a popular way to improve MySQL's performance. As an important feature for improving MySQL's performance, the query cache was often recommended as a solution for slow queries. However, why has MySQL 8 abandoned the query cache? Today, we will analyze and explore this decision. What is query cache? According to official document: The query cache stores the text of a SELECT statement together with the correspon...

   MYSQL 8,QUERY CACHE     2023-03-11 09:05:17

  How Kafka achieves high throughput low latency

Kafka is a message streaming system with high throughput and low latency. It is widely adopted in lots of big companies. A well configured Kafka cluster can achieve super high throughput with millions of concurrent writes. How Kafka can achieve this? This post will try to explain some technologies used by Kafka. Page cache + Disk sequential write Every time when Kafka receives a record, it will write it to disk file eventually. But if it writes to disk every time it receives a record, it would ...

   BIG DATA,KAFKA     2019-03-08 09:42:57

  How long does the heuristic cache of the browser actually cache?

Heuristic cache Heuristic caching is the default behavior of browser caching (i.e., for responses without Cache-Control), which is not simply "not caching", but implicitly caching based on the so-called "heuristic cache". HTTP is designed to cache as much as possible, so even if Cache-Control is not specified, the response will be stored and reused if certain conditions are met. This is called heuristic caching. HTTP/1.1 200 OK Content-Type: text/html Content-Length: 1024 Date: Tue, 22 Feb 2022 ...

   HEURISTIC CACHE,WEB DESIGN     2023-05-26 08:40:13

  Content based HTTP Cache

Browsers may cache the webpages we visited, when user types a URL on the address bar, the browser may cache the webpage returned from server while displaying it. If there is no update on the webpage, then next time when the browser requests the same page, it will not download the page again, instead it will load the cached page. If the website explicitly specify that the page is updated, then the browser will download the page again from the server. What's HTTP Cache? You may be familiar with th...

   HTTP Cache,Web crawler     2013-05-24 05:12:59

  Meta tag in HTML header

In server response, we can use response.setHeader() to set the meta information in header of a HTML page. The usage is response.setHeader(name,context); meta is used to simulate the response header of HTTP protocol in HTML page. It should be put between the <head> and </head> tag. 1. <meta name="Generator" content="" > <!--This is to specify the tool which generates this page such as Microsoft FrontPage 4.0 etc --> 2. <meta name="keywords" content=""> <!-- To tel...

   HTTP,meta,HTML,head     2013-05-22 11:34:08

  Be careful when running knife vault command

While using Chef, one would frequently use knife commands which are used to manage resources on the Chef server. One can list all nodes, data bags, vault items and many other stuff on the Chef server. In this post, we would cover one command which may need your attention when using it -- knife vault. On Chef server, one can store data to data bags which can be accessed by registered clients. These data bags usually store the data in plain text format. In some cases, one would need to store data ...

   KNIFE VAULT,KNIFE DATA BAG,CHEF-VAULT,CHEF     2017-08-19 00:26:54

  What will the value of Integer.valueOf(127) == Integer.valueOf(127) be in Java?

Do you really understand how Java does the integer comparison? OK, ignore the statements in the post title. What we are interested in is another set of comparison statements. Let's first see below code snippet. public class IntegerComparison { public static void main(String[] args) { Integer a = 127, b = 127; Integer c = 128, d = 128; System.out.println(a == b); System.out.println(c == d); } } What do you think the output will be? Are they both displaying true? You will find out t...

   JAVA,==,EQUALSTO     2018-01-13 22:18:15

  Differences among Enter,F5 and Ctrl+F5 in webpage refresh

When we press Enter, F5 or Ctrl+F5 to refresh a webpage, is there any difference among them? Actually it's yes, we can find the difference from the request header and response header information. There are two cases about pressing Enter in the address bar. First if the page requested is cached and not expired in the browser, we can find the header information sent by the browser is : Host 192.168.3.174:8080 User-Agent Mozilla/5.0 (Windows NT 5.1; rv:5.0) Gecko/20100101 Firefox/5.0 Accept ...

   Refresh,F5,Ctrl+F5     2013-06-13 22:03:35

  Redis Cluster and Common Partition Techniques in Distributed Cache

In this post, I will discuss a few common partition techniques in distributed cache. Especially, I will elaborate on my understanding on the use of Redis Cluster. Please understand that at the time of writing, the latest version of Redis is 4.0.10. Many articles on the same topic have a different idea from this post. This is mainly because, those articles are probably outdated. In particular, they may refer to the Redis Cluster implementation in Redis 3. Redis Cluster has been improved...

   REDIS,DISTRIBUTED CACHE,CLOUD COMPUTING     2019-01-17 08:10:37

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