Database Administrator

Hive optimization tips-How to Write HQL I. Hive join Optimization 1. try to place the small table on the left of join. The hive-0.12.0 we use here is automatically converted. This means that the small table is automatically loaded into the memory

NoSQL series: Redis (1) Redis environment preparation rredis function library rredis basic Use Cases Each chapter is divided into "text description" and "code section" to ensure consistency between the text description and the code. Chapter 1

Oracle null value processing function /*********** NUL, NVL2, and NULLIF usage in Oracle ***************/ NULL indicates a NULL value or an invalid value. 1. NVL (expr1, expr2) Function If expr1 is NULL, expr2 is returned. If not NULL, expr1 is

How to obtain the variable value bound to an Oracle SQL statement When diagnosing SQL Performance problems, we sometimes need to obtain the actual value of the variable it binds, and then bring the actual value into the SQL statement, use the

Internal Management Mechanism of Oracle Share Pool The share pool is managed using HEAP memory management. It is physically composed of multiple memory zones (EXTENT) and consists of multiple chunks of different sizes. The CHUNK can be reused and

Oracle GoldenGate Install For Linux, oraclegoldengateDownLoad: Http://edelivery.oracle.com Prepare (Source And Target DB): Add Environment Variblevi/home/oracle /. bash_profileexport LD_LIBRARY_PATH = $ ORACLE_HOME/lib:/usr/lib:/opt/ogg Configure

In DBMS_METADATA, use SESSION_TRANSFORM to filter DDL and dbmsmetadata. When dbms_metadata.get_ddl is used to obtain the object ddl, other additional information is sometimes obtained. For example, when you want to obtain the table creation

Mysql research-MySQL built-in function ParsingZookeeper Note: 1) it can be used in SELECT/UPDATE/DELETE and where, orderby, and having. 2) use the field name as a parameter in the function. The value of the variable is the value of each row

The ehcache cluster uses the rmi method. There are several methods for ehcache clusters: rmi, jgroup, and jms. Here we will talk about the use of ehcache. The reason why ehcache uses rmi to copy the cache is as follows: 1. rmi is the default Remote

Several Methods to view the variation trend of scn headroom, scnheadroomMethods for viewing the variation trend of scn headroomThis article does not explain the scn headroom problem. This article summarizes the script from the oracle sr technical

OTL Chinese garbled OTL UTF8, otl Chinese garbled utf8 Character encoding is supported by odbc when unixODBC is used to connect to MySQL. It does not require any compilation conditions when compiling OTL in C ++. If your database uses UTF-8

Pay attention to designing system updates and patches.We usually develop a system that must be upgraded frequently. Upgrading means modifying the code or data structure. Of course, you should try to modify the data structure as little as possible in

Data source rejected establishment of connection, message from server: "Too many connections", establishmentDetailed error message: Severe: StandardWrapper. ThrowableOrg. springframework. transaction. CannotCreateTransactionException: cocould not

Install mysql on mac and macmysql Method 1: If you have installed homebrew, you can directly install it through homebrew. There are tutorials online. Method 2: Method 2: Download the mysql Installation File dmg on the official website and

Use of % TYPE and % ROWTYPE in ORACLE, % type % rowtype 1% TYPE description To make the data TYPE of a variable consistent with that of another defined variable (especially a column in a table), Oracle provides the % TYPE definition method. When

The standard script automatically started by osw in linux as the operating system starts. The standard script that osw starts with the startup of the operating system in linux. Osw refers to OS watcher, which is a shell script for monitoring various

Hive SQL optimization: distribute by, sort by, and hivedistributeHiveSQL has been optimized recently, The following is an SQL statement that sorts records from the first row of each group after grouping.

How to bypass the password settings of the oracle listener and use oraclelistenerZookeeper How to bypass the password settings for oracle listening: 1. Find the pid of the listening process and kill it.Ps-ef | grep tns [Oracle @ lixora admin] $

[Translated from mos] enabling dblink's oracle net trace/tracing and mosdblink Enable dblink's oracle net trace/tracing -- Method for tracking dblink. Reference Original:DBLINK: How to Enable Oracle Net Tracing for Database links (Doc ID

Deepen understanding of Oracle outer connections (left/right/full), inner connections (oracleinner), andOracle's left join, right join, and (+) Outer Join types are always confused. The experiment is used to deepen the understanding of the