Database Administrator

Oracle table join Note the difference between left join on and where when connecting Oracle tables: Select * from dept; Select * from emp; Select * from emp a right outer join dept B on a. deptno = B. deptno where a. empno is null; Select

Oracle 11g maintenance partition (2) -- Coalescing Partitions Integrated Partition Converged partitioning is a method to reduce the number of partitions in a hash partition table or index. It can also be used to reduce the number of subpartitions in

Oracle checks the master database, physical and snapshot slave databases through views and alarm logs Oracle checks the master database, physical and snapshot slave databases through views and alarm logs Master database action Master

Stop using MongoDB! Sven Slootweg (joepie91) is a hacker and the creator of CrytoCC. It now provides the Node. js code review service. Recently, he posted a blog post on his personal blog titled why you should never use MongoDB forever, forever, and

Oracle creates databases and users In the past, mysql and SQL server were mostly used during development, while Oracle was rarely used and unfamiliar. mysql and SQL server were used in a similar way, the usage of Oracle is different from that of

What do you know about MySQL passwords? This article will introduce some MySQL user password-related knowledge and some security improvements in 5.6. How is the MySQL user password generated and saved? If you have been in touch with MySQL for a

Undo tablespace usage The undo tablespace is a very important tablespace in Oracle databases, and its usage is also the focus of DBAs. However, in busy production systems, it is easy to see that the undo tablespace usage is very high, or even 100%.

Oracle client Dedicated and Shared connection mode Dedicated (Dedicated mode)User processes and server processes are separated.Each user process has its own server process.User and server processes can run on different machines to take advantage of

MySQL function: group_concat () function GROUP_CONCAT (expr)This function combines non-null column values according to grouping conditions and returns the result. If a null value exists, null is returned. The complete syntax is as

Recovery database encountered a ORA-0600 fault Errors in file/u01/admin/UIDB/udump/uidb_ora_59394.trc:ORA-00600: internal error code, arguments: [krbrrd_bz2_ksfqrd_noblks], [/u01/test/tests], [576000], [], [], [], [], [], [], []Full restore complete

Using MySQL as a NoSQL, mysqlnosql FROM:Using MySQL as a NoSQL-A story for exceeding 750,000 qps on a commodity server Due to the limitations of MySQL, many sites adopt the MySQL + Memcached architecture. Some other sites use NoSQL instead of MySQL,

NUTCH2.3 hadoop2.7.1 hbase1.0.1.1 solr5.2.1 deployment (2), hadoop2.7 InstallationZookeeper Precondition:Hadoop 2.7.1Hbase 1.0.1.1/hbase 0.98.13 192.168.1.106-> master192.168.1.105-> slave/regionservers Hbase deployment Directly download the hbase

NUTCH2.3 hadoop2.7.1 hbase1.0.1.1 solr5.2.1 deployment (3), hadoop2.7 InstallationZookeeper Precondition: Hadoop 2.7.1Hbase 0.98.13Solr 5.2.1/Apache Solr 4.8.1Http://archive.apache.org/dist/lucene/solr/4.8.1/Gora 0.6.1 Gora compilation and Nutch

[MySQL] (4) operation data table records, mysql DATA 1. INSERT record Method 1: INSERT [INTO] tbl_name [(clo_name,...)] {VALUES | VALUE} ({expr | DEFAULT },...), (...),...; For example: Create table users (id smallint unsigned primary key

About how hibernate inserts Chinese data into the mysql database with garbled characters, I have been studying hibernate these days. When I used hibernate to insert data into the mysql database in the program, I found Chinese garbled characters and

SUSE Linux source code compilation and installation MySQL 5.6, susemysql This article mainly introduces how to install MySQL 5.6 in SUSE Linux Source Code compiling mode. This article uses SUSE Linux Enterprise Server 10 SP3 (x86_64) system. For

Install mysql in ubuntu 1204 and ubuntu Check whether mysql is installed on the local machine sudo netstat -tap | grep mysql After executing the preceding command, the mysq socket is in the listening status, indicating that the installation is

High-concurrency and high-traffic website architecture: simple ideas and concurrent traffic Architecture*******************************Front end*******************************1. Increase the necessary hardware and bandwidth, and reserve an

Left join, right join, and mysqljoin in mysql Left (outer) join: The left table is dominated by all rows in the left table. The right table lists the data that meets the requirements of the record. Right (outer) join: The right table is the

SQL Injection and prevention, SQL Injection preventionSQL Injection: SQL Injection refers to inserting SQL commands into Web forms to submit or enter query strings for domain names or page requests. In this way, the server can finally execute