Database Administrator

Http://www.infoq.com/cn/news/2014/01/neo4j-2 Recently, Neo Technology released Neo4j 2.0 GA with a brand new graph browser, node label, an optional mode, and improved Cypher. The most noteworthy improvement of Neo4j 2.0 is the brand new browser UI,

 1. Memory Management, add at the end of the file /Etc/sysctl. conffs. aio-max-nr = 1048576 fs. file-max = 6815744 kernel. shmall = 2097152 kernel. shmmax = 536870912 kernel. shmmni = 4096 kernel. sem = 250 32000 100 128 net. ipv4.ip _

Use cursor) 1. Declare a cursor Cursor for select_statementThis statement declares a cursor. You can also define multiple cursors in a subroutine, but each cursor in a block must have a unique name. A single operation is performed after the cursor

Both PostgreSQL and Oracle provide statements such as row_number () over () to rank corresponding fields, which is very convenient. MySQL does not provide such a syntax.Recently, due to the increasing demand for migrating data from Oracle to MySQL,

After twists and turns, we finally successfully configured Oracle11GR2 ASM when the vmwarevm Redhat Enterprise Linux 6 has installed a single-node Oracle database 11G R2. The record process is as follows: Environment: VMWare Player 5.0.2 build-103176

1 using () is used for join queries on two tables. The column specified by using () must exist in both tables and is used as the join condition. Example: select. *, B. * from a left join B using (colA); equivalent to: select. *, B. * from a left

MySQL does not support online table redefinition like Oracle itself, but we can use the open-source software percona-toolkit tool pt-online-schema-change for online redefinition. Official documents:

2.3.2. Store JavaScript. Developers can access JavaScript Functions and values on the server side without using stored procedures in relational databases.2.3.3. aggregation. MongoDB supports MapReduce and other aggregation tools, which provide

Simple Application of triggers A trigger is a special stored procedure. The difference is that the stored procedure needs to be called, and the trigger does not need to be called. During certain operations, the trigger will automatically execute.

How can I transfer data in Ubuntu 12.04? This discussion gives the general direction: Http://askubuntu.com/questions/224/how-to-i-move-mysql-data-files-onto-different-partition The default data file path is the/var/lib/mysql directory, but the disk

Let's explain with Lao Guo:Step 1: store the changed data to PGA Step 2: copy the old data in the buffer cache to the private IMU buffer in the sharing pool. Step 3: store the modified data in PGA to private redo Step 4: modify data in the buffre

Sp. param_value nvarchar2 (200 );     Select sp. param_code, to_number (sp. param_value), sp. param_value, length (param_value)From sys_service_param spWhere sp. param_type_code = 'bank'And sp. param_value = to_char (0.78, '0. 00 ') Why does to_char

The statement to be executed was not found. Later, the function was completed. It was originally run once every minute, but it was not run for a long time. It was normal to run it manually. Why did it suddenly stop working? In addition, it is

Alter session set events '10231 trace name context off '; Segment_name = sys_lob2017119493c00006 $Segment_type = LOBSEGMENT Column_name = WORD Set serveroutput onDeclareN number;Error_code number;Bad_rows number: = 0;Ora1578

While (rs. next ()){Count ++;String ip = rs. getString ("ip ");Int port = rs. getInt ("port ");String type = rs. getString ("type ");LOG. debug (count + "get" + type + "proxy:" + ip + ":" + port );Try {CheckSocksProxy (ip, port, type );} Catch

Http://blog.csdn.net/chszsI. OverviewApache CouchDB and CouchBase NoSQL databases are both open-source and free NoSQL document-type databases, and JSON is used as the document format. The similarities between Apache CouchDB and CouchBase are

A database is a collection of large amounts of data that can be shared and organized in a computer that has been stored for a long time.1. database data features P4Permanent storage, organized, and shared.2. Data independence and how to ensure P10

Simple Application of Stored Procedures Stored Procedure: executes a task that contains a series of pl SQL statements stored in the database and becomes an object of the database. The efficiency is relatively high, but when you create a stored

1. -- case sensitiveSelect * from a where a = 'abcde' collate Chinese_PRC_CS_AI -- case sensitiveSelect * from a where a = 'abcde' collate Chinese_PRC_CI_AI -- case insensitive2. If you want to make all the storage tables on the server case

When adjusting Data Guard to maximum protection in the max PROTECTION mode), you encountered the following problem: end-of-file on communication channel. The execution process is as follows:   SQL> alter database set standby database to maximize