Database Administrator

1. Composite data type-record type Ø syntax format Type name is record ( Field 1 Field 1 type [not null]: = expression 1; Field 2 Field 2 type [not null]: = expression 2; ... ) Description: records must be of the same type when values are assigned

Zookeeper QQ numbers are subject to privacy interference. Sorry. Many people think that in the company, if you have optimized dozens of SQL bosses, you will be given a higher salary, or if you have something special about bbed recovery, you will be

I went to an interview with two cool Internet companies a few days ago and encountered problems in SQL. Well, unfortunately, let's take a look at it. Score 1. Use group Group by Dimension For example: Calculate the total score of each

1. the following error is reported during Mysqldump: 2014-05-05 14:12:37 7f004a9a2700 InnoDB: Error: Table "mysql". "innodb_table_stats" not found. However, show tables indicates that it exists: But the show create table innodb_index_stats; error

ORA-01925: maximum of 80 enabled roles exceededMax_enabled_roles 9i parameter, 10 Gb or later. Specifies the maximum number of enabled roles for a user session.MAX_ENABLED_ROLES specifies the maximum number of database roles that users can enable,

This operation can be performed on the map or reduce side. The following is an example of a business scenario. Brief description: Assume that the key input by reduce is Text (String), the value is BytesWritable (byte []), there are 1 million

Top:Top-16:41:04 up 184 days, 2 users, load average: 19.97, 18.38, 18.36Task: 584 total, 1 running, 583 sleeping, 0 stopped, 0 zombieCpu (s): 0.0% us, 0.0% sy, 41.2% ni, 58.7% id, 0.0% wa, 0.0% hi, 0.0% si, 0.0% stMem: 65923008 k total, 34622724 k

 Exp/imp environment variable character set Conversion Note: ensure that the client encoding is the same as the database encoding to avoid character conversion. Other methods ensure that the exp client encoding is the same as the imp client

AlwaysOn has been released for a long time since SQL Server2012. Recently, When I consulted some customers, I was often asked if AlwaysOn should be used, from the customer's perspective, it seems that AlwaysOn is a cure for all diseases, but there

Issue: Cannot resolve the collation conflict between "Chinese_PRC_CI_AS" and "SQL _Latin1_General_CP1_CI_AS" in the equal to operation. Issue One day in a multinational company, DBA set up a database Server for testing in Beijing. This DB Server is

CUME_DIST and PERCENT_RANK functions in SQL SERVERCUME_DIST and PERCENT_RANK Functions CUME_DIST: calculates the cumulative distribution of a value in a group of values in SQL Server 2012. That is, CUME_DIST calculates the relative position of a

Yesterday, my colleague said that a test database could not be logged on. After logging on with PLSQL Developer, the following message is displayed: ERROR:ORA-00604: error occurred at recursive SQL level 1ORA-01653: unable to extend table SYS. AUD $

Zookeeper impdp fail with ora 31623 FYI: Data Pump import and export job use queues, streams and java objects. If we see any job component is invalid (e.g. dbms_java, queue dictionary scripts not run, rdbms/admin/utlrp. SQL not run) we may see the

The dbms_stats package can be used to collect statistics. The following syntax is usually used: exec dbms_stat.gather_table_stats (ownname => 'xxx', tabname => 'xxx', estimate_percent => xxx, method_opt => 'xxx', cascade => xxx ); Among them,

In the past, when using relational databases, we could not access data without a user name or password. However, in MongDB, you can access the database without the user name or password by default and perform various operations. This is not safe for

Connect to MongoDB using Java Package mymaven; import java.net. unknownHostException; import java. util. set; import com. mongodb. basicDBObject; import com. mongodb. DB; import com. mongodb. DBCollection; import com. mongodb. DBCursor; import com.

Range Step 1: Apply the correct index Make sure that each table has a primary key.   Step 2: create an appropriate overwriting Index SalesPersonID Sales ProductID 112 NCLIX_Sales_ProductID Use Database adjustment

I. PrefaceIn the past, because the table design was complex (multiple tables have direct master-slave relationships with tables), this was determined by the business logic. The insertion efficiency is simply intolerable and must be optimized. After

The sequence starts from 0 every morning after the Oracle stored procedure is updated. Create a stored procedure for Oracle first; For example, clearing a table Create or replace procedure pro_job_delete As Begin -- Dbms_output.put_line ('System

For more blog posts, please note: Children without umbrellas must keep running.(Www.xuchanggang.cn) I. Xtrabackup Overview:Xtrabackup is a mysql database backup tool provided by percona and supports online hot backup. according to the official