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Go A, b two tables, find the ID field, there is a table, but there is no data in table B. A total of 13w data, after the deduplication of about 3W data, b table has 2W data, and B table ID field is indexed. Method OneUse not in, easy to understand, low efficiency ~ Execution Time: 1.395 seconds ~ (the first method of pro-test is available)1Selectdistinct a.id from A where a.id not in (select ID from B) Method TwoUse left Join...on ..., "b.id is

until it finally succeeds, and the user program consumes more CPU and performs poorly. In fact, the operating system provides a Select method to replace this repeated read polling for state judgment. Select internally determines whether the data is fully read by examining the event state on the file descriptor. But it is still only a synchronization for the application, because the application still needs to proactively determine the status of I/O, and it still spends a lot of CPU time waiting,

the bandwidth is w, then the Rtt*log 2W time can be full of bandwidth. Congestion avoidance: from a slow start, it can be seen that CWnd can grow quickly to maximize the use of network bandwidth resources, but CWnd cannot continue to grow indefinitely, certain restrictions are needed. TCP uses a variable called Slow-start threshold (ssthresh), and when CWnd exceeds that value, the Slow-start process ends and enters the congestion avoidance phase. For

1. Why encode because the CPU only knows the numbers2.ASCII A character is a total of 7 bits, expressed in one byte, a total of 128 characters3. So the ASCII wasted the highest bit much pity that appearediso-8859-1, a byte, 256 characters, the default encoding for many protocols4. Chinese encodingGB2132 two bytes, continental use, representing about 6k charactersBIG5 two bytes, traditional encoding standard, total 1.3w charactersGBK expands GB2132, can represent

transmission process, uses the 0V to represent the numeral 0,5v to represent the number 1, then each code element has two states 0 and 1. Each code element represents a binary number. at this point the number of yards per second and the number of binary code per second is the same, which is called two-phase modulation, the baud rate is equal to the bit rate. if 0V, 2V, 4V, and 6V represent 00, 01, 10, and 11 respectively in the digital transmission, then each code element has four states 00, 01

, Yi):Defining the Super Plane (w,b) The function interval for the training dataset T is the Super plane (w,b) minimum function interval for all sample points (xi, Yi) in t2. Disadvantages of function interval:|| The distance between the point x and the plane is inaccurate, as long as the proportional change is w,b. For example, change to 2w,2b. The hyper-plane does not change, but the function interval is twice times the original. Descriptio

in format "C S T". C is a letter indicating the initial running direction of Tom, and it can be ' W ', ' E ', ' N ' or ' S ' standing for West, east, N Orth or South. S is Tom's speed (1≤sSample input:4E 1 1W 1 124E 1 1W 2 154E 2 2W 3 150Sample output:2 23 32 12 43 14 1The main topic: (1), the first line of input is n (ending with n equals 0), indicating the range of a given n*n, initially placing two rabbits in (n,n) position. (2), the second

Brief introductionThis system resolves offsite disaster preparedness for 2w+ database instances (including MYSQL,REDIS,SSDB)About 40w+ a backup file per day (99% DB instance for hourly backup policy)40tb+ data volume per day for offsite transfersSupports any backup This system is only responsible for backup offsite transfer, not responsible for how to back up the specific backup script users write their own, as long as required to write the b

current training institutions, to change the resume of graduates to achieve high salaries. In the embedded industry is relatively small, but Andrid, iOS, these application layer development positions are more, most training institutions to change their graduates to a few years of work experience. The outcome is high expectations, and they can not independently undertake development tasks, resulting in the failure to pass the probationary period. This kind of fresh graduates high salary is obvio

Update Leetcode to solve Java answers on a regular basis.Choose a topic using pick one.The title means to find the length of the longest ordered continuous array, given an unordered array.The idea is to assume that the input array's number range is between -10000~10000, create an array of 2w space, assign a value of 0, traverse the given array, treat the array value as an array subscript, create an array corresponding to the value +1, and finally iter

Test-topickafkamirror,topic1,0-0 (Group,topic,brokerid-partitionid)Owner = kafkamirror_jkoshy-ld-1320972386342-beb4bfc9-0Consumer offset = 561154288= 561,154,288 (0.52G)Log size = 2231392259= 2,231,392,259 (2.08G)Consumer lag = 1670237971= 1,670,237,971 (1.56G)BROKER INFO0-127.0.0.1:9092Note that the –zkconnect parameter needs to be specified to the zookeeper of the source cluster. In addition, if the specified topic is not specified, all topic information under the current consumer group is pr

https://uva.onlinejudge.org/index.php?option=com_onlinejudgeItemid=8page=show_problemproblem= 2151Http://7xjob4.com1.z0.glb.clouddn.com/f1186ae9a93d903ab533e5fce524bac6Test instructions: Give you a hand, output all the cardsIdea: Enumerate all 34 kinds of cards, in order to determine whether to listen to this card, the first enumeration to select will, and then enumerate the CIS, inscribed, etc., recursive judgment.1#include 2 using namespacestd;3 4 Const Char*mahjong[]={5 "0",6 "1T","2T","3T","

, but it is people tired point. On the tools if you increase the risk, the cost of preventing the risk also needs to be considered. In the past, the wrong operation at most one, now I am afraid that all lost in the operation. Therefore, pragmatism is the most important.If not the boss, hundred will consider the business operations tools, at least the vendor support, if the boss chose the open source tools, simply to save money, but after the incident, blame is not the open source community, but

Kernel:TCP:time wait bucket table overflow problemRecently collected system logs with elk, found that some machines have many kernel errorsThe majority of the online version of the argument is to net.ipv4.tcp_max_tw_buckets this kernel parameter to increase. But not the principle.I thought about it, in fact the meaning of tw_buckets is that the time wait bucket table is full.Why is it full?netstat -an|moreSee Time_out's linkUsually 80 ports, that is, Web server caused, then it is natural to thin

next line of this column of the grid form a piece. So set this position 0, the corresponding position of the previous line is 1.In such a case, there will be no conflict of circumstances.The first line requires special consideration because there is no previous line before the first row, so there is only one case if you want to put it vertically.Reference to other people's code, is written with Dfs, very concise, learning.1#include 2#include 3#include 4#include string>5#include 6 using namespac

DescriptionWe all love recursion! Don ' t we?Consider a three-parameter recursive function w (A, B, c):If a 1If a > B > or C >, then W (A, B, c) returns:W (20, 20, 20)If a W (A, B, c-1) + W (A, b-1, C-1)-W (A, b-1, c)Otherwise it returns:W (A-1, B, c) + W (A-1, B-1, C) + W (A-1, B, C-1)-W (A-1, B-1, C-1)This is a easy function to implement. The problem is, if implemented directly, for moderate values of a, B and C (for example, a = d, B = d, c = All), the prog Ram takes hours to run because of t

, first high school to now more than six years of girlfriend away from me, and then his father because of long-term work pressure and irregular rest, diet, suffering from depression, and then many organs have different degrees of injury, poor health, can not be excited, an excited heartbeat, And then can't control where to cry, always said I am good hard, or worse than the death of such words, the first time to see the father onset, I know how terrible depression, when the sister still has two m

program occurred too many open files, but did not know. Lsof-p 6022 Java 6022 FS 1w REG nbsp 8,8 5006 3014678/home/xxx/log.log Java 6022 FS 2w nbsp REG 8,8 5006 3014678/home/xxx/log.log Need careful Check if the handle is having too many file code problems. I have had a handle leak before. Also code write problem (third-party software internal source code did not study thoroughly), constantly repeated open fileinputstre

1910 Recursive Functionstime limit: 1 sspace limit: 128000 KBtitle level: Golden GoldTitle DescriptionDescriptionFor a recursive function w (A, B, c).If a If a > B > or C > 20 returns W (20,20,20).If a In other cases, return W (a? 1, B, c) + W (a? 1, b? 1, C) + W (a? 1, B, c? 1)? W (a? 1, b-1, c-1)This is a simple recursive function, but it may be problematic to implement.Enter a descriptionInput DescriptionThere will be several lines. Three numbers per line, indicating a, B, C. and 1,? 1,? 1 en

Original: Redis Core interpretationRedis is a well-known key-value database that is widely used in caching systems. Information about Redis has not been introduced to me much. The Redis article of this system is mainly concerned from another angle, redis as an open source project, a short 2W line of code contains a robust server-side software required, we can learn the programming style of C language projects from Redis, Paradigm, learning Unix-like s