Database Administrator

PostgreSQL recursive query for Tree Structure Query A very interesting feature found during PostgreSQL's use is that recursive queries can be used for results that require a tree-like structure. For example, the data structure of common company

About MySQL database optimization from the O & M perspective A mature database architecture is not designed with high availability, high scaling, and other features at the beginning. It is gradually improved with the increase in the number of users.

Test the Online DDL function of MySQL 5.6. The predecessor of online DDL is innodb fast index creation (5.1 and 5.5). This function is extended in 5.6: Many alter table operations bypass table copying and support concurrent DML operations. 1.

HBase learning Summary (5): HBase table design, hbase table I. How to start Pattern Design When talking about schema, consider the following:(1) How many columnfamily should this table have?(2) what data does the column family use?(3) How many

One of the primary MongoDB series: MongoDB installation and recommended configuration; Primary mongodb Analysis The first time I heard about apsaradb for MongoDB, I must have heard a lot about it before I decided to learn about it. No matter what

Beckham _ mysql trigger and Beckham _ mysql triggerTriggerBrief1. Basic concepts of triggers2. Trigger syntax and practical examples3. Differences between before and after   I. Basic concepts of triggers 1. Instant Transmission 2. Role: monitor a

Mongodb introduction, mongodb Brief description: MongoDB is a distributed file storage-based database. Written in C ++. It is designed to provide scalable, high-performance data storage solutions for WEB applications. MongoDB isRelational

Vertica database operations, vertica Database Delete a primary key (the primary key value of the Vertica database is not unique ):SELECT ANALYZE_CONSTRAINTS ('fb _ s. c_log ');Find the key name, and then:Alter table fb_s.c_log drop constraint

Mongodb distributed cluster (1. Master-slave replication), mongodb master-slaveUnderstanding of distributed Clusters There are many explanations on the concept of distributed clusters. I prefer "distributed clusters" as two concepts, that is,

Statistical analysis table of stored procedures in case of ORA-00600 error analysis and processing, stored procedures ora-00600 1. Part of the stored procedure of the statistical analysis table Createor replace procedure SEA. sp_analyze_XXX_

Group function and group statistics, group function statistics Grouping Functions Grouping functions commonly used in SQL Count (): Count Max (): calculates the maximum value. Min (): Minimum value Avg (): calculates the average value. Sum (): Sum

Mysql load data command parses and processes error 29 (ErrCode: 13) (In ubuntu environment), errcodeubuntu On the mysql server, run the following command: load data infile 'file_name' into table table_name; Store all data in a text file in a

Record the troubleshooting and resolution of a deadlock, and record the troubleshootingThis is a sad reminder. I remember last week's busy schedule. The goal is to modify some bugs in the code left by another team. This project is used for OLAP

Causes of slow night dimension execution: Execution inquiry Let's take a look at the key release today. Two days ago, I worked with my colleagues to check whether the execution of the overnight program was abnormal and slow. This was a typical

Locate an interesting error in selecting the Execution Plan (involving SYS_OP_C2) and execute the plan sys_op_c2. These two days and guangfen's brother read a question, which is interesting and the process is tortuous... Symptom: 1. 11g library,

Primary Key and unique constraint of 14-SQLite, primary key of 14-sqliteI. Primary Key Uniquely identifies a row (one table can only have one primary key) Primary keys should be meaningless to users (often used for indexing) Never

Mysql study Note 3 (INDEX), mysql study note IndexIndex Database Object Index: A combination of data. By indexing objects, you can quickly query specific records in the database object table. It is the most common way to improve performance. An

Expdp export encountered ORA-39064: unable to write log file, expdpora-39064 Expdp export encountered ORA-39064: unable to write Log File .. Exported "USER_XXXX". "TAB_YYYY" 0 KB 0-line ORA-39064: unable to write Log File ORA-29285: file write error

MySQL Study Notes _ 7_MySQL common built-in functions and Study Notes _ 7_mysql MySQL common built-in functions 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.

Mysql 5.6 installation-free configuration in win7 64-bit system, win7mysql 1. Download the official zip package and decompress it to the local directory. 2. Modify the my. ini file copy default. ini and [Client] port = 3306default-character-set =