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(*) > 1; " > uid_double.txtawk'{print" delete from user_mapping where platform= "$ 1 "and uid=" "$"; "} ' uid_double.txt >-uusername-ppassword user_del Step4. Modify the User_mapping table to re-establish the UID as the primary keyAlter Table Add Primary Key (UID);Step4. Constructs a statement that queries the UID in the uid1202 table in the User_mapping tableMysql-uusername-ppassword user_del-e"select uid from uid1202" > uid.txt awk'{print ' Select Open_id,platform,serverid from user_mapping

|+----------+1 row in Set (0.16 sec)Now you can index it, explain the real SQL statement on the line.Mysql>explainselectpost_idfromtest.tbl_testwherepost_type Add indexMysql> ALTER TABLE Test.tbl_test Add index Idx_f (check_status,flag,post_type,post_time); Query OK, 0 rows affected (4.45 sec) records:0 duplicates:0 warnings:0One more explain, scan 500,000 lines to 2 lines.Mysql>explainselectpost_idfromtest.tbl_testwherepost_type After you have debugged the index, determine that you can optimiz

Environment: MyBatis + oracle11g R21. Use Direct path insertion ("/*+append_values */" in the following SQL statement) and use keyword "union ALL":2.dao layer implementation: Before a one-time commit, this will increase with the number of inserts, the speed of the operation is very slow, so should be inserted in batches:public void Save (list MyBatis BULK INSERT Oracle Massive data logging performance problem Resolution

Environment: MyBatis + oracle11g R21. Use Direct path insertion ("/*+append_values */" in the SQL statement below) and use the keyword "union ALL":2.dao layer implementation: Before a one-time commit, this will increase with the number of inserts, the execution speed is very slow, so should be inserted in batches:public void Save (listMyBatis BULK INSERT Oracle Massive data logging performance problem Resolution

lock read statement with the current read, read the original row, because the general read and write does not conflict, so InnoDB will not appear read-write starvation situation, Also because the use of the index is a row lock, the size of the lock is small, the situation of the same lock competition is less, the increase in concurrency processing, so the efficiency of concurrent reading and writing is very good, the problem is that the index after the query based on the primary key two search

minutes. Read here is a more than 7 million-line file, updated record about 300多万条.My $db _handle = Dbi->connect ("dbi:mysql:database= $database; host= $host", $db _user, $db _pass, {' RaiseError ' = + 1, autocommit = 0}) | | Die "Could not connect to database: $DBI:: Errstr"; eval {while (!eof ($FD)) { $CloudID = The first time to start is to execute SQL, so the speed is very slow! Set autocommit = 0, and then commit, the speed is greatly improved. Copyright NOTICE:

, if it is not the public method, it needs to setaccessible (true); Then invoke the value of the field in the instance and database. All code: Directly copy the past can be used, you change the IP definition of your entity class just fine, if you can't add me QQ468165108 Jar Package used: Ojdbc14.jar,mongo-2.5.3.jar Jar:http://pan.baidu.com/s/1ktgnvoj Password: 69FZ, public void Odbctomongo () throws Exception {Mongo Mongo = new Mongo ("192.168.1.3", 30000); DB db = Mongo.getdb ("test");

Operating System: Windows XP SP3 Symptom: the page is blank. Cause: Incorrect HTML character encoding Test reproduction: IE6/8 has no problems and is monopolized by IE7: source if you cannot see this text, note: IE7 does not

Copy codeThe Code is as follows:DEMO code: [Ctrl + A select all Note: If you need to introduce external Js, You need to refresh it to execute]Source: http://www.cnblogs.com/airy

Copy Code code as follows: Effect Demo Code: [Ctrl + A All SELECT Note: If the need to introduce external JS need to refresh to perform] Source: Http://www.cnblogs.com/airy

ExampleThere is a 1G size of a file, each line is a word, the size of the word does not exceed 16 bytes, memory limit size is 1M. Returns the highest frequency of 100 words.Ideas First, separate the files. For each file hash traversal, count

Code implementation c6> #include"stdafx.h"#include#includeusing namespacestd;inta[1000000];inttempa[1000000];#defineBegin_record \{clock_t ____temp_begin_time___; ____temp_begin_time___=clock ();#defineEnd_record (dtime) \Dtime=float(Clock ()-_

When it comes to sorting large data volumes (100W or more), the following three sorting methods are used: quick sort, merge sort, heap sort. At this level, other bubbles, selection, insertion sort, etc. have not been seen at all, the efficiency is

A recent project uses the Kafka client to receive messages, requiring that they be written to the file (in order). There are 2 ideas: 1. Use log4j to write the file, the advantage is stable and reliable, the file according to the setting,

1.SQLSERVER database to change the bit type to not Boolean (that is, to change true to False;false to true) Example: Update table set bit field =bit field-1 Recently a friend asked me, he said that he deleted millions of to tens of millions of data

To the users of Photoshop software to explain the detailed interpretation of the use of action to automatically handle a large amount of pictures of the tutorial. Tutorial Sharing: In this tutorial, we will create a PS action

"What is Bit-map?"The so-called bit-map is to use a bit bit to mark the corresponding value of an element, and key is that element. Because the bit is used to store the data, the storage space can be greatly saved. If there is so much to know about

II. Improving SQL statements Many people do not know how SQL statements are executed in SQL Server, fearing that their written SQL statements will be misunderstood by SQL Server. Like what: SELECT * FROM table1 where Name=zhangsan and TID >

1. ETS and Dets Introduction: ETS (Erlang term Storage) and Dets (Dist ETS) are system modules that Erlang uses to efficiently store large numbers of Erlang data entries. ETS vs. Dets: Same: Both ETS and Dets provide large "key-value" search tables.

Redis is a high-performance Key-value database.The emergence of Redis, to a large extent, compensates for the lack of memcached such keyvalue storage, in some cases can be a good complement to the relational database.Redis is essentially a key-value