Database Administrator

An error is reported during data migration between Hive and MySQL databases using Sqoop. Run./sqoop create-hive-table -- connect jdbc: mysql: // 192.168.1.10: 3306/ekp_11 -- table job_log -- username root -- password 123456 -- hive-table

Use MySQL-Proxy for MySQL database read/write splitting Experimental System: CentOS 6.6 _ x86_64Prerequisites: Firewall and selinux are both disabled.Tutorial Description: In this experiment, there are a total of four hosts, with IP addresses

ORA-00382 and DB_nK_CACHE_SIZE parameter settings Recently, I tried to optimize a query that contains the blob field table and considered using a non-standard block cache. However, an error occurred while trying to set the DB_32K_CACHE_SIZE

MySQL stored procedures and program calls in Java A stored procedure is a program stored in a database (just like a subroutine in a regular language). To be precise, MySQL supports two types of "routines (routines: one is the stored procedure, and

Four full recovery scenarios in archive Mode In data backup and recovery, rman is basically used, but from the internal principle of the database, for media recovery, there are actually two things to do: restore and recover.Restore is a copy similar

Learning notes on five types of Redis objects When using Redis, we directly access String, List, Hash, and Set objects ), sortedSet. Basic commands include String (get set) List (lpush rpush lpop rpop lrange) Hash (hget hset hlen hgetall) set (sadd

MySQL primary key constraints and uniqueness constraints MySQL primary key constraints and uniqueness constraints are both indexes. The differences between them are: The primary key field can be unique, but the primary key field cannot be NULL.

Redis command details Redis command details 1. set setnx setex Set associates the value of the string value with the key. If the key already exists, it overwrites the original one. If it does not exist, it is created. Setnx sets the key value as

Redis Command Execution Process This problem is simple and simple. The client sends a command request, the server reads the command request, and then the command executor searches for the command implementation, executes the Preparatory operation,

Mysql database batch quick insert, mysql database Recently, when processing a batch of data, you need to process the fields in the database table and then export them to a new table. However, this table has nearly million data records. The problem

Usage of select distinct in mysql, mysqldistinctWhen using mysql, you sometimes need to query records with unique fields. Although mysql provides the keyword distinct to filter out redundant duplicate records, only one record is retained, but it is

Using excel for data mining (7) ---- filling data from examples, excel Data Mining After configuring the environment, you can use excel for data mining. For environment configuration problems, see:

The size of the datafile recorded in the Oracle database datafile header, datafileheader   Environment: Oracle Databae 12.1.0.2, rhel5.9 x86-64bit   [Oracle @ rhel59 orcl] $ pwd/u01/app/oracle/oradata/orcl [oracle @ rhel59 orcl] $ ls-lrttotal 2104544

Hash index and BTree index, and Hash index BTree Index An index is a data structure that helps mysql obtain data. The most common indexes are Btree indexes and Hash indexes. Different engines have different support for indexes: Innodb and MyISAM

Mysql compilation and installation tutorial in Linux (centos), centosmysql How to compile and install mysql in Linux # Viewing the linux release version Cat/etc/issue # View the Linux kernel version Uname-r Test Environment centOS6.6   I.

Mongodb addition, deletion, modification, and query * ******************************** 1. insert ******************************** use tblorders; -- Method 1db. tblorders. insert ({orderno: "A2014089901", pname: "tblorders", scity: "beijing"}); db.

Innodb change buffer passive merge, innodbbuffermergePassive merge scenario 1: insufficient secondary index page space: ibuf0ibuf. cc: ibuf_insert_low 1. When a cache insert operation is attempted, if the estimated space of the secondary index page

Use of JDBC Package com. jack. jdbc; import java. SQL. connection; import java. SQL. driverManager; import java. SQL. preparedStatement; import java. SQL. resultSet; import java. SQL. SQLException; // JDBC case public class JDBCTest {// use JDBC //

Database isolation level, database isolation level There are four database transaction isolation levels, from low to high: Read uncommitted, Read committed, Repeatable read, Serializable, these four levels can solve dirty reads, non-repeated reads,

Joint server test (2) and Joint server test I haven't written it here for a long time, and I moved my own data from other places. Here we will mainly introduce the business layer. After these tests, we will simply complete the combined Server test.