retracement levels

asp.net| data Many database operations need to be transacted, and there are roughly 3 levels of transactions under ASP.net: (1) Transaction at the level of the stored procedure (2) Ado.net-level transactions (3) asp.net transaction at the page level Here are some examples: First create Trantest table, field ID (int), test (char) Set primary key for ID (use primary key is not allow duplicate attribute for transaction test) (1) CREATE PROCEDURE Tran1 A

Tablespace_name) Totalwhere free.tablespace_name = total. tablespace_name; Step four, insert data into the new table in parallel. Sql> alter session enable parallel DML; Insert/*+ Append Parallel (p,8) */into P_transaction_bak P select/*+ Parallel (n,8) */* from p_transaction Nwhere To_char (n.operationdate, ' yyyy-mm-dd ') =To_char (to_date (' 2016-07-05 ', ' yyyy-mm-dd '), ' yyyy-mm-dd '); Commit; Step five, back up the old table. sql> rename p_transaction to P_transaction_old; Step six, re

inconsistent results for 12 statistics of the thread, as in the case of hallucinations.Serializable because a range lock is obtained, and the transaction is executed serially one after the other, it guarantees that no phantom reads occur.Thus, the higher the isolation level, the less interference with other things, the worse the concurrency performance.Set syntaxOracle:SET TRANSACTION Isolation Level serializable| READ committed| READ uncommitted| Repeatable READ;Sybase:SQL Opreation at Isolati

"client angle" post-write read because there may be multiple clients running concurrently. When we design architecture for a business application, we look at the problem from the client's point of view. The isolation level , which is the visibility of data between transactions, is discussed in the "parallel write process, or some written (committed) and some that have not yet been actually written (uncommitted) in this process", while the consistency study is what happens when everyone writes,

will not lock the read to the row3. When the transaction isolation level is read Committed, the write data will only lock the corresponding row4, when the transaction isolation level is repeatable read, if there is an index (including the primary key index), the index as a condition to update the data, there will be a gap lock gap lock, Row lock, the next key lock problem, thereby locking some rows, if there is no index, the update data will lock the entire table. 5. When the transaction isolat

level is enabled, each time the row is updated, the SQL Server database engine stores a copy of the original row in tempdb and adds the transaction sequence number to the row. Snapshots and MVCC At present, most relational databases use 2PL protocol to ensure the serialization of concurrent transaction execution, which creates the problem of read-write mutex, that is, s lock and X-lock mutex. The multi-version concurrency control (multi-version Concurrency CONTROL,MVCC) solves this problem b

read and will not lock the read to the row3. When the transaction isolation level is read Committed, the write data will only lock the corresponding row4, when the transaction isolation level is repeatable read, if there is an index (including the primary key index), the index as a condition to update the data, there will be a gap lock gap lock, Row lock, the next key lock problem, thereby locking some rows, if there is no index, the update data will lock the entire table. 5. When the transacti

additional hidden values are added after each row of data to implement MVCC, which is a record of when this row of data is created and another record of the rowWhen the data expires (or is deleted) in the actual operation, the storage is not the time, but the version number of the transaction, each opening a new transaction, the version number of the transaction will beIncreasing. Under the REPEATABLE READ Transaction ISOLATION level:Select, read create version number is not greater than curren

repeatable read and will not lock the read to the row3. When the transaction isolation level is read Committed, the write data will only lock the corresponding row4, when the transaction isolation level is repeatable read, if there is an index (including the primary key index), the index as a condition to update the data, there will be a gap lock gap lock, Row lock, the next key lock problem, thereby locking some rows, if there is no index, the update data will lock the entire table. 5. When th

Tags: SQL DCL Create user authorization View permissionsDCL1. Create a user* CREATE user username @ip address identified by ' password ';> users can only log on to the specified IP address* CREATE user username @ '% ' identified by ' password ';> Users can log on at any IP address2. Authorization to the user* GRANT permissions 1, ..., Permissions n on database. * To user name @ip address> Assign the user the specified permissions on the specified database> For example, Grantcreate,alter,drop,ins

1 uncommitted read (READ UNCOMMITTED): Dirty data will appear because the table is not locked.2 Commit read (Read Committed): 1. Update in transaction 1 locks the table and can select to the latest data.Transaction 2select cannot find the data. Will always wait. Plus with (NOLOCK) you can read it.2.select is an unlocked table, so other transactions can modify the data. When there are two select,The second select will show dirty data. cannot be read repeatedly.3 REPEATABLE READ (REPEATABLE Read):

How to check the database schema version, patch levels, and general monitoring readiness for patches in SharePoint Central Administration: Make sure that you are a farm administrator with access to central administration. Start: 1. Open Central Administration-upgrade and migration. 2. Click "View product and patch installation status". 3. A drop-down list at the top allows you to choose whether to view the entire farm or just the parts on a particular

Tags: x11 body div State full graphics into Inux Linux systemThe Linux system has 7 runlevel (runlevel): RunLevel 0: System down state, system default RunLevel cannot be set to 0, otherwise it will not start normally RunLevel 1: Single User working status, root privilege, for system maintenance, remote login Forbidden RunLevel 2: Multi-User State (no NFS) RunLevel 3: Full multiuser State (with NFS), enter console command line mode after login Run Level 4: System not used, reser

|+------+------+3 Rows in Set (0.00 sec) B> commit;Query OK, 0 rows affected (0.01 sec) The modification of a here should be num=3, but because of the Phantom reading, the thing B is submitted, but the thing a reads the old record,Like Phantom, when thing a changes, it finds that the result is 30, not the desired result 3a> Update test set num=num*3 where id=1;Query OK, 1 row affected (0.03 sec)Rows matched:1 changed:1 warnings:0 A> select * from test;+------+------+| ID | num |+------+------+|

According to the parameter Display category (three levels of association, JSON data is required ), Scripts/Category. js Call method:$ (Function () {BindCategory (); // BindCategoryData ($ ("# txtCategoryId"). val () by default, BindCategory ());})View Code Binding three levels of linkage (see: http://www.cnblogs.com/haozhenjie819/p/3887279.html for details)Function BindCategory () {var $ txtCategory = $ ("#

Simple implementation of three levels of Ajax Product Classification Association (case study ), Train of Thought Analysis: Effect: When a page is loaded, ajax is used to asynchronously request data from the background to load the first-level commodity category. When the first-level commodity is selected, the second-level commodity is loaded and the second-level commodity is loaded. Implementation: 1. After obtaining the data, load the product with a p

point), for example:Assume that the following route matching rules are registered (the controller, the webapi of the action, and the character of the route) Config. Routes.maphttproute ( name: "Defaultareaapi", routetemplate: "Api/{area}/{controller}/{action}/{id}", defaults:new {id = routeparameter.optional} ); Config. Routes.maphttproute ( name: "Defaultapi", routetemplate: "Api/{control

Tags: HTTP Problem c html ef r management HTM TTIn an enterprise, listening is the basis for communication between managers and employees. However, in reality, many people do not really master the art of "listening. According to the analysis, there are different levels of listening.The lowest is "listen without hearing": As you have heard, you have never heard of it;The second is "perfunctory": Well ...... Oh ...... Good ...... Ah ...... A slight reac

In Android, citypickerview, an open-source framework, is used to achieve three levels of association between provinces, cities, and cities,1. Overview I remember that when I was working on a mall project, I needed to implement provincial/municipal linkages in the address selection to facilitate users to quickly enter the address. At that time, I used an open-source control called android-wheel, at that time, I felt very easy to use. The only trouble w

Test your understanding of MySQL transactions and isolation levels. I have written an article titled MySQL InnoDB Transaction isolation level and dirty read, Repeatable read, phantom read Http://blog.csdn.net/seven_3306/article/details/27085275 This is a question I have figured out about MySQL transaction and isolation level. Please fill in the question mark section: If you can correctly explain the following results, you should have a certain und