BloomFilter can be used to quickly determine duplicate values from big data
MySQL Working With Dates
The most difficult part when working with dates is to be sure that the format of the date you are trying to insert, matches the format of the date column in the database. As long as your data contains only the date portion, your queries will work as expected. However, if a time portion is […]
MySql AUTO INCREMENT Field
If you accidentally lose the primary key and need to modify the id column of the table as the primary key, you can use the following SQL statement
JSTL format timestamp
JSTL format timestamp, for example, how can 1444226313 be displayed as 2015/10/7 21:58:33?
How to solve tomcat exception error:Invalid character found in the request target
How to solve tomcat exception error:
java.lang.IllegalArgumentException: Invalid character found in the request target. The valid characters are defined in RFC 7230 and RFC 3986
Distributed system unique id generation algorithm Twitter Snowflake
In a distributed system, how to solve the unique sequence problem, how to solve the duplication id problem, there are currently many algorithms can be solved, today we introduce a classic solution: Twitter SnowFlake
About the English association football league
The Premier League, often referred to as the English Premier League or the EPL outside England, is the top level of the English football league system. Contested by 20 clubs, it operates on a system of promotion and relegation with the English Football League (EFL). Seasons run from August to May with each team playing […]
JVM performance tuning monitoring tool hprof use detailed
Ⅰ Problem In real-world enterprise Java development, sometimes we encounter the following problems: OutOfMemoryError Memory leak Thread deadlock Lock Contention Java process consumes too much CPU …… These problems may be overlooked by many people in daily development (for example, some people encounter the above problems just restart the server or increase the memory, but […]
Ali Open Source Java Diagnostic Tool-Arthas
Arthas is an open source tool for Java developed by Alibaba recently. It mainly for diagnosing the problems of java. I. Overview This tool can help you do the following things: Which jar package loaded this class from? Why do you code throws various kinds of Exceptions? If you encounter problems on product environment , […]
Mysql delete duplicate records and only keep one row
Recently, I have been working for a subject storehouse system. Since duplicate subject are added to the storehouse, it is necessary to query the duplicate subject, and delete all duplicate subject leave only one, so that the duplicate subject cannot be taken when the test is taken. First wrote a small example: Single field operation […]