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Tags: style io color using SP strong data on 2014Clear Oralce cache: Alter system flush Buffer_cache;Environment: Oracle 10g, 4 million data, frequency 5 minutes1. Application scenario: Find the latest data for all sites. The SQL statements are as follows:——————————————————————————————————————————————————With AA as (Select T1. EQP_ID, Max (measure_time) Maxtm from Plu_water_data t1 where

1. Delete from T1 where condition 2, delete t1 from T1 where condition 3, delete t1 from T1,t2 where condition 4, delete t1,t2 from t1,t2 where condition The first 3 are feasible, a

column1 column2 column1 column2 td> column3 column1 key1 td> key2 Key3 td> As shown in the figure above, Key1,key2,key3 is the only row key value for three records, Column-family1,column-family2,column-family3 is a three-column family, and several columns are included under each column fami

operations, the Operation Sequence of transactions A and B is scheduled randomly. If the preceding scheduling sequence is used, the modification of transaction a is lost. Cause: in step 1, transaction B modifies transaction A and writes it back, which overwrites the data inconsistency (inaccuracy) caused by concurrent modification operations of transaction A (Lost Update) non-repeatable Read: reads Dirty data (Dirty Read) Mark R (x): Read data xW (x ): write Data x two transactions

This article mainly introduces the MySQLreplaceinto statement analysis (2). This article focuses on several special case studies. For more information, see 1. Introduction The previous article introduced the basic principles of replace. This chapter uses an example to describe the potential data quality risks caused by replace into. when a table involved in the replace into operation contains an auto-incrementing primary key, after the master-slave switchover, data overwrites and other inconsis

MySQL replace into Statement Analysis (2), mysqlreplace 1. Introduction The previous article introduced the basic principles of replace. This chapter uses an example to describe the potential data quality risks caused by replace into. When a table involved in the replace into operation contains an auto-incrementing primary key, after the master-slave switchover, data overwrites and other inconsistencies may occur. Case Study Operate on the master databaseCopy codeThe Code is as follows:Root @ te

follows:n= no matter what kind of running environment you run the above command, you will get the same result: n=1000. This is a good indication that each of these threads must have been executed, so n must be equal to.The join method of the multi-thread join method is not used much, and when a thread executes to the join () method of the B thread, a waits for the B thread to run, and the A thread executes. When you use the Join () method, an exception is generated.Use a small program to illus

This article mainly introduces the MySQL replace into the sentence analysis (ii), this article focuses on a number of special case analysis, the need for friends can refer to the An introduction The basic principle of replace into is introduced in the previous article. This chapter provides an example of the potential data quality risk associated with the replace into, and when a table involving a replace into operation contains a self-added primary key, the primary switch causes inconsistenci

program.Of course, the update work is handed over to the Adapter. The main technology is to synchronize the changes to the able read from the two databases.DataTable is used here.EventResponse, I use:Add: DataTable. TableNewRow; DataTable. RowChanged;Delete: DataTable. RowDeleting; DataTable. RowDeleted;Change: DataTable. ColumnChangedThe following uses table T1 T2 as an example to describe theseEventHow to be triggered and how to handle the trigger.

With the release of Hive0.10, GROUPINGSETS emerged and provide clauses in the ROLLUP and CUBE special scenarios. With the release of Hive 0.10, grouping sets have emerged, and the clauses of roll up and CUBE are available. With the release of Hive 0.10, grouping sets have emerged, and the sub-statements for roll up and CUBE are very popular. However, when I recently wrote two HQL query scripts, I found that when GROUPING expressions BY and using GROUPING SETS to customize the GROUPING methods o

Oracle rman database backup and recovery in non-archive mode, mongolerman1. database Backup SQL> archive log list in non-archive mode; automatic archiving in non-archive mode in Database Log mode disable the archiving end point USE_DB_RECOVERY_FILE_DEST the earliest online log sequence 3244 the current log sequence 3246 RMAN> run 2> {3> allocate channel t1 type disk; 4> backup database format 'e: \ rman_bak \ 20111103 \ df _ % t _ % s _ % p. bak '; 5

Object permission test: in the Initial State, neither user2 nor user3 has the object permission of user1.t1. Object permission test: in the Initial State, neither user2 nor user3 has the object permission of user1.t1. Object permission test:In the initial state, neither user2 nor user3 has the object permission of user1.t1.Table

cascade operation and sets all data in the foreign key table to a null value.--set default: Similar to set NULL, the data in the Foreign key table is set to the default value.--primary key table and foreign key table: T1.id is the foreign key of table T2, and is the primary key of table T1, then for t1.id, table T1 is

Continue to look at the second case of the query, including the table connection: SQL> Create Table T as select * From dba_users; The table has been created. SQL> Create Table T1 as select * From dba_source; The table has been created. SQL> ALTER TABLE t add constraint pk_t primary key (username ); The table has been changed. SQL> ALTER TABLE T1 add constraint fk_t1_owner foreign key (owner)2

In Oracle, if the table data volume is large (M-level or larger), updating a field is very slow (for example, updating the historical business process table in my HIS project, 1.6 million records, use CURSOR to update, 1000 COMMIT once, it took four days to complete the update), and later tried to improve: 1. Cancel LOGGING on the table 2. Cancel the INDEX of the table But it is still very slow, but you can find this: Http://asktom.oracle.com/pls/asktom/f? P = 100: 11: 0: P11_QUESTION_ID: 640799

in a parallel manner.2)-W--width Specifies the width of the column when using the-y parameter.3)-C display all the text, and mark the difference.4)-u-u--unified displays the different contents of the file in a merged manner.5)-R--recursive comparing files in subdirectories6)-N--rcs Displays the comparison results in RCS format.(4) Example:1) [[Email protected] document]# diff t1.txt T2.txt compare two document differences[email protected] document]#

relational database that is in compliance with the specification (SQL specification). However, there are some differences between MySQL and Oracle , because the implementations of each vendor may be different. Sql99 is intended to standardize the general syntax of multiple relational databases .1.5.Basic syntax for multi-table joinssyntax for Sql99:syntax for Oracle:SQL Statement optimization:Plus the prefix: High efficiency!1.6.Internal Connection1.6.1.Intra-equivalence connectionEquivalent co

undolog inside write. Of course, this write must not be casually written in, in the writing, it is sure to check whether the previous transaction is completed.This time there is a problem, because the database is always running, that is, the transaction is constantly started, and there may be n transactions are already in the start state. When the checkpoint is written, there may be a new transaction started, and if the checkpoint waits until there is no new transaction to start and all the pre

From the very beginning, when I got started with js, I felt flexible. Everyone's writing methods were different. For example, a function has N types of writing: 1. function From the very beginning, when I got started with JavaScript, I felt flexible. Everyone's writing methods were different. For example, a function had N writing methods. For example: function showMsg () {}, var showMsg = function () {}, showMsg = function (){} There seems to be no difference. They are all the same. Is it true?

){document.write(s+"");}Function From the very beginning, when I got started with JavaScript, I felt flexible. Everyone's writing methods were different. For example, a function had N writing methods, such: function showMsg(){}var showMsg = function(){}showMsg = function(){} There seems to be no difference. They are all the same. Is it true? Let's take a look at the example below: /// Functions // function Definition: Name function (declarative), anonymous function (referenced) // declarative