Database Administrator

Oracle 10 Gb read-only table N methods Sometimes to improve data security, we need to set one or more tables to read-only, that is, no DML (Insert, Update, Delete) operations can be performed on them. It is very easy to implement read-only tables in

HBase quick data import-BulkLoad Apache HBase is a distributed, column-oriented open source database that allows us to access big data at random and in real time. But how can we effectively import data to HBase? HBase has multiple data import

Oracle 11g DataGuard usage Summary Compared with 10 Gb, Oracle's 11g replica uard has the most advantageous feature of active replica uard. This improvement has prompted users to upgrade the database from 10 Gb to 11 GB, read/write splitting is

ORA-12154 TNS cannot parse the specified identifier Report on using pl/SQL developer to access a remote Linux database in WinORA-12154 TNS cannot parse the identifier, but SQLPLUS is normal under WinC: \> tnsping lin_hjj TNS Ping Utility for 64-bit

Install MySQL 6.4 Binary Package in 64-bit CentOS 5.6 I do not like it because I want to install MySQL in Linux and it is very complicated to use the source code package: 1. You need to install the GCC compiler. While I installed linux with minimal

MySQL rolls back the insert statement, leading to a doubling of ibd files' MySQL rolls back the insert statement, which causes the ibd file to increase by a factor of one. A simple test: Start transaction;Insert into tb1 values (3, repeat ('A', 650

TOAST function in PostgreSQL The content of TOAST in PostgreSQL is stored in another object, which is different from the OID of the original table. Similar to the LOB type storage in Oracle (the out-of-line Storage is stored in lobsegment by default,

Percona MySQL5.6 semi-synchronous Replication Configure normal clone first Two servers, one master and one slave Master Server: 10.10.1.30 Slave: 10.10.1.200 Modify the my. cnf file of each machine and the server_id Master server server_id = 1,

Fastdb's Chinese Character truncation error In Fastdb C #, if the field type is defined as CLI. FieldType. cli_asciiz, garbled characters may occur when the Chinese character set is inserted, Tracing code found that during the CopyBufferData process

Error reported when the cli_autoincrement auto-Increment Variable is defined in Fastdb, fastdbcli I recently tried to use fastdb for development. The test in c ++ version is basically OK. Because the project team adopts C # development, I switched

Oracle table partition, oracle Partition The partition of the pivoel table can basically be divided into several categories:-Range Partition-Hash Partition-List partitions-Combined partitions: Range-Hash and Range-List.1. Create a partition table

SQL computing time difference execution stored procedures, SQL time difference stored procedures -- datediff (day, 'compare time', GETDATE ()) DECLARE @ ctime INTSELECT @ ctime = datediff (day, (select max (InDate) FROM OrderSettlement), GETDATE (

JPA cache and jpa CacheJPA Cache For JPA2.0, cache can be classified into Level 1 cache and level 2 cache (JPA1.0 only supports Level 1 cache ). The second-level cache is usually used to improve the performance of applications. It can avoid

SQL syntax, SQL SQL refers to the structured query language.The following is a table named "Persons": id auto-increment, no need to worry Basic SQL statements include addition, deletion, modification, and query.Add: The insert into statement is

Analysis of SQL statement execution time and resource consumption using profilessql Open profiling, which is disabled by default. mysql> set profiling=1; Execute the SQL statement to be analyzed mysql> select count(1) from wechat_employee,Employee;

Beckham _ redis string type learning, _ redisstring RedisString type 1. View string-type commands Ii. string operation example     1. View string-type commands 1. Open the redis client and enter help 127.0.0.1: 6379> help Redis-cli2.8.19 Type: "help

Beckham _ redis set/zset type learning, _ rediszset Redis set and zset types I. collection type 2. view set and zset set commands Iii. set and zset set instances     I. collection type 1. There are two types of redis collections: ordered and

Redis data type string, redis Data TypeRedis data type string redis string The redis string is not a C-language native string, but a self-built simple dynamic string (SDS), which is similar to a C-language native string, use '\ 0' as the end. In

Hive count distinct, hivedistinct Select count (distinct user_id) from dm_user where ds = 20150701; With the disticnt function, all data is shuffled to only one CER, causing serious data skew of reducer. After optimization Set mapred. reduce.

MySQL Common commands -- create command use, mysql -- create Create Database create database db_test;create database if not exists db_test;drop databases if exists db_test; Create Table create table if not exists t_user( uid varchar(50)