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2018 is known as the winter year of the Internet. Companies, big and ...
Added by amar3d on Mon, 29 Jun 2020 09:51:49 +0300
Article Java AQS Queue Synchronizer and ReentrantLock Application This paper introduces the implementation of AQS exclusive acquisition of synchronization state, and illustrates how ReentrantLock customizes synchronizer mutually exclusive lock.
Article Java AQS Shared Obtain Synchronization Status and Semaphore Application Analysis In ...
Added by hank9481 on Wed, 24 Jun 2020 05:01:25 +0300
1, Problem description
2, Step by step analysis of problems
1, java.net.SocketException : how is the broken pipe exception generated? What's the impact?
2. Why is the database TCP connection broken?
3. The effect of firewall cutting off database connection
1. Adjust the cut-of ...
Added by Popcorn on Fri, 05 Jun 2020 10:51:02 +0300
In the Oracle database, the optimizer needs to rely on the collection of statistical information of related objects in order to generate the optimal execution plan. The database can automatically collect the execution plan or use the package DBMS_STATS is collected manually. This article does not explain the collection of general statistics. It ...
Added by libertyct on Wed, 27 May 2020 15:38:34 +0300
---------------------------------------------------------------Table building----------------Determine whether the student table exists
declare num number; --Declare parameters num type number
select count(1) into num from user_tables where table_name='student';
if num>0 then
execute immediate 'drop table st ...
Added by crinkle on Thu, 21 May 2020 18:21:15 +0300
In Oracle and SQL Server databases, you can set up some complex account password policies, such as locking an account more than N times after a failed login, so can you do the same in MySQL?The answer is that MySQL has similar capabilities, except in MySQL it delays the response time when its login fails beyond the threshold, instead of locking ...
Added by marco839 on Tue, 19 May 2020 20:23:28 +0300
Modifying and listening IP address of oracle
Reference and combine these two blogs Modifying and listening IP address of oracle Oracle modify listening IP address
In a very simple way, the problem of monitoring is solved.
Now let's combine and rearrange it
1. In cmd, enter hostname discovery hostname
2. Modify the ...
Added by ubunken on Tue, 05 May 2020 23:03:59 +0300
In the previous section, we talked about the configuration of haproxy's access control ACL. For a review, please refer to https://www.cnblogs.com/qiuhom-1874/p/12817773.html ; Today let's talk about the configuration of haproxy's https, tcp-based four-tier load balancing, and access control.
First let's look at the configuration of haproxy's ht ...
Added by amandas on Sun, 03 May 2020 09:12:33 +0300
select * from emp where rownum=1 or rownum=2;
select * from (select * from emp order by sal desc) where rownum<5;
select * from (select rownum no,e.* from(select * from emp order by sal desc) e where rownum<=5) where no>=3;
select * from (select rownum no,e.* from(select * from emp order by ...
Added by infid3l on Sat, 02 May 2020 23:53:05 +0300
OS: CentOS release 6.6
RAC: 22.214.171.124.0 dual node ASM Library
1. Cause of failure
Today, four data files are added in batches. add datafile '+ DATADG' in the second to fourth data file add SQL misses' + '. After oracle successfully adds the first data file, it is found that the second data fil ...
Added by grahamb314 on Fri, 01 May 2020 22:00:41 +0300