Channel 4 China blog: InfoQ database framework draft revised text interview

by:dbanotes@gmail.com(Fenng)

Author:Fenngpublished in thedbanotes.net.

inInfoQto myinterviewafter it is published, I can see that site has been reproduced in the text. In fact, things switch to oral text, his speech is not so inevitably some of the local Dayi, InfoQ Thailand to seek the views of stability, I am here for questions and answers on the part of the amendment, so as not to mislead.

Following is the text:

Jason: As a senior DBA, but large-hui in his BLOG to write a lot of the top structure on the site of some articles in this area, can not talk about the DBA with the site structure in this area relations »

Fenng: Many friends and I joked that I do a DBA, but the structure related to write some things, "is not the cooks do not see recipes, see the Art of War» "In fact, this I think it is between some relations. Like database maintenance, and even design, architecture-related work, to a certain extent still have to walk a few steps forward: that is to say we should structure some things related to the integration come. Of course it was not necessary as a DBA must be relevant as the architect of our case, to do something like the actual coding work, but some of the DB compared with the close of the things we must look at, and this is what I wrote in BLOG A lot of structure and the related article, one of the main reasons.

Jason: in general to enhance the performance site, What are the major bottleneck, to address these bottlenecks, there is what best practices?

Fenng: In the past, most likely will be the bottleneck in the database, which means that the final bottleneck will fall on IO above. But now with some Web2.0 emerged in the development of related technology solutions, the current site can really cope with the large flow, with high, the main problem lies in Cache full, flexible and proper use, it is very important . [Added that because this is the basic topic-oriented aspects of Web 2.0, said here Cache is the main problem, as you know, e-commerce sites, transaction processing capacity is relatively difficult things:

Jason: to withstand a large-scale, high with the visit of the success of Web2.0 test site in the design of the structure necessary to pay attention to what things do?

Fenng: this early in the planning is certainly needs to be done in a number of preventive measures, for example, choose the appropriate technology infrastructure. This is the first step should be to consider the matter. There are also in product design, it will also need a lot of attention, now many of our Web 2.0 site, including domestic some of these new Web 2.0 site, more or less, there are someexcessive designof Phenomenon. These designs may have inadvertently brought devastating impact on the background, which will be developers, architects and even maintenance personnel have brought great pressure.

On the other hand, it refer to some of the current industry has been relatively mature technology DIY framework structures still very critical. We do a site like making cars, like Mercedes-Benz do not have to create such top-level luxury (the cost will be very high), we just made a runs, ran a very good car, which may have been To the success of the half.

Jason: It said in the website performance and tuning in this area, you have just mentioned, the cache is a very important role, then how is it in the end an important position like this » How to optimize the cache to improve performance?

Fenng: In my previous experience, based on the Oracle environment some practice, on the one hand is complicated by the application of high-design some of the issues important to note, the other is how well Oracle use their own memory, the last of its essence is whether full use of their own Cache mechanism. The Web 2.0 site, may have little use Oracle database (more than is MySQL), but in MySQL on the one hand, MySQL have their own Cache mechanism, it should be said also done quite well, then one would consider the use of the vast majority of sites likeMemcachedsuch external components in, and then in this place, in fact, we consider that the last shot, to measure the level of shooting, We must pay attention to the scalability, performance indicators.

loss hit the I/O in fact the final pressure to our database, to the database of I/O to hit the loss may be pressure to the bottom of the disk, this disk storage [or] must be able to support living Our current minimum requirements. For the most simple example, the application of Memcached, may be in front of the I/O hit rate is 80 percent, then have the remaining 20%will be pressure to the back of the DB, the DB's shooting may have reached 95 percent, while the remaining 5 percent, multiplied by 20%in front of that, in general I/O volume x 20%x 5%, the I/O volume will reach the final end of the hard drive or storage [on]. The hard disk storage [and] the overall response capacity is limited ... perhaps we are doing RAID, also may even drive a single application support such a situation. Pushed forward from this basis, we will be able to calculate the current system can carry Cache bottlenecks, and further that the overall I/O processing power. In the design of the time, we must take into account this situation, otherwise the pressure suddenly increased when we can not afford the time to do some temporary expansion of the means, may be relatively trouble.

Jason: You just mentioned Cache hit rate, for a more successful this site, Cache hit rate will generally be in how many?

with Oracle, its own shooting to 90 percent or even 99.99 this is the case, the MySQL environment may do so, Memcached As far as I know, probably 70 percent to 80 percent have a pretty good [Different from the performance of different applications, such as watercress friend told me that they hit rate is 97%!]. Of course, shooting is only a superficial phenomenon, we really depends on the actual application in the end is what may be different types of Web applications to load the frequency of visits do not like, so there is no fixed ratio here can only be based on Some experience. Overall, the higher the rate must be hit, some of the better.

first part of a first here. Tomorrow time that the remaining part.

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