Database Administrator

V $ database: database information, such as the database name and creation time. V $ instance information, such as instance name and start time. V $ parameter information, select * from v $ parameter where name like '% name' ----> show parameter

Flashback version query is not a new feature of Oracle, but the 10g and 11g functions are enhanced on the basis of 9i, which may be used in some occasions. The following example shows his concept;   ConnectedToOracleDatabase11g

A properly configured Mongodb sharding cluster does not have a single point of failure.This article describes several potential node failure scenarios in a sharded cluster and how Mongodb handles these node faults. 1. Mongos node downA Mongos

After installing the database, I found that em could not log on. I thought that I didn't notice this before creating the data. I reconfigured it. Oracle @ linux: ~> Sqlplus/as sysdba SQL * Plus: Release 11.2.0.1.0 Production on Thu Jan 5 09:44:14 201

Oracle uses the table () function to replace the result set returned by PL/SQL. 1. table () combined with Arrays: Create or replace type t_test as object (Id integer,Rq date,Mc varchar2 (60)); Create or replace type t_test_table as table of

Oracle indexes are organized and stored in the form of a Balance Tree: stores the value of the index column, a part of the rowid (file number, block number, row number) The following is an example: 1, create table test (id int, name varchar2 (20

Now there is a table (mt) with at least million data every day, and we plan to build a partition table in the form of monthly partitions. When partitioning, let Oracle run faster 2, said p21. [SQL] SQL>AlterSystemSetDb_create_file_dest ='F: \

1. Mongo objectA connection pool is implemented internally. Mongo objects are thread-safe. Therefore, you can create only one Mongo object and use it safely in a multi-threaded environment. Therefore, we can use the Mongo variable as a member

MongoDB is a scalable, high-performance, open-source, free-mode, document-oriented database. It is not a commonly used RDBMS and belongs to the database category of the popular NoSql database. It is not the same as a general key-value-based db

Database Version:SQL> select * from v $ version;BANNER----------------------------------------------------------------Oracle9i Enterprise Edition Release 9.2.0.1.0-ProductionPL/SQL Release 9.2.0.1.0-ProductionCORE 9.2.0.1.0 ProductionTNS for 32-bit

The process of a Delete operation in OracleDELETE)1. Oracle reads the Block to the Buffer Cache (if the Block does not exist in the Buffer)2. record the details of the delete operation in the redo log buffer.3. Create an undo entry in the

Select grouping (vsaltype) as sq, Vsaltype | 'subtotal 'vsaltype, Sum (amount) as amount, ''Vvin, ''Vpropertywh, ''Vpropertywhdesc FromSPTW90_INVENTORY_NCS_TMP Group by rollup (vsaltype) The result is as follows: : Analysis conclusion: Grouping: If

You do not need to add content in server. xml or web. xml.First:Create a file context. xml under the project META-INFJava code "Jdbc/myOracle"Auth ="Container" Type ="Oracle. jdbc. pool. OracleDataSource"Factory ="Oracle. jdbc. pool.

There are four functions that support regular expressions in Oracle: 1. REGEXP_LIKE: similar to LIKE 2. REGEXP_INSTR: similar to INSTR 3, REGEXP_SUBSTR: similar to SUBSTR 4. REGEXP_REPLACE: similar to REPLACE They are used in the same way as Oracle

I encountered some trouble. Although it was not solved, it was a reminder. Today, the username created with Grant is "DanielW", and the logon password is incorrect. Create a new one. The username is "Daniel @ localhost", that is, add the host name,

Continue with the previously installed Oracle11g R2 (see). Here we use putty to log on to the linux system. The advantage of putty is that it can be copied and pasted on linux and windows at will, it is also very convenient to copy files to each

There are already many articles about NoSQL selection. Factors that affect your database include read/write throughput, persistence, consistency, and latency. The document "Visual Guide to NoSQL System" by Nathan urst summarizes this

If the SQL statement contains fields not in the table, the following error occurs: Android 2.3.3 Eclipse Version: 3.7.0 Console LogCat error message: 02-23 11:20:41.360: ERROR/AndroidRuntime (4366): Android. database. sqlite.

When I read the Mysql manual again today, I see a function concatenation field that is ignored at ordinary times. In fact, it is simple to use mysql functions to process strings. The calculated field is usually used, but the spliced field is ignored.

1. Perform the delete operation.SQL> drop table t;Table dropped.SQL> select * from tab;TNAME TABTYPE CLUSTERID-----------------------------------------------BIN $ wWGJJd0UCrDgRAAMKRcWyg = $0 TABLETTS SYNONYMTTSS SYNONYMSQL> purge table t;Table