lifelock guarantee

blown up (generally to make the maximum space limit for auto-expanded tablespace)Sql>create undo tablespace undotbs2 DataFile '/u01/oradata/timran11g/undotbs02.dbf ' size 100m autoextend on;The original undotbs01.dbf is in the active state, and the newly added undotbs02.dbf is standby:Sql>select tablespace_name,status,contents from Dba_tablespace;To toggle the Undo table Space:Sql>alter system set undo_tablespace= ' UNDOTBS2 ';To delete the Undo table space:The Undo table space in the active st

Kafka in versions prior to 0.8, the high availablity mechanism was not provided, and once one or more broker outages, all partition on the outage were unable to continue serving. If the broker can never recover, or a disk fails, the data on it will be lost. One of Kafka's design goals is to provide data persistence, and for distributed systems, especially when the cluster scale rises to a certain extent, the likelihood of one or more machines going down is greatly increased, and the failover req

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and load operations sequentially, and execute the store and write operations sequentially if you want to synchronize the variables from the working memory back to the main memory. These two operations must be executed sequentially, but there is no guarantee of continuous execution, that is, between read and load, and between store and write, other instructions can be inserted. In addition, the Java memory model also stipulates that the following rule

: For reordering that alters the execution of the program, JMM requires that the compiler and processor must disallow this reordering. For reordering that does not change the results of the program execution, JMM requires that the compiler and processor do not require that this reordering be allowed. the definition and rules of Happens-beforeJSR-133 uses the concept of Happens-before to specify the order of execution between two operations, since both operations can be within a

, the result may be 0 or 6 or 3 because two threads cross execution.Shared variables are not visible primarily for the following reasons:A. Cross-execution of threadsB. Re-orderingC. Shared variables not updated in a timely mannerBy using synchronized, you can guarantee atomicity (synchronized code block content is either not executed, execution is guaranteed to complete) and visibility, and the modified code adds synchronized keywords to the write an

The volatile variable provides the visibility of the thread and does not guarantee thread security and atomicity. What is the visibility of a thread: Locks provide two main features: mutexes (mutual exclusion) and visibility (visibility). Mutual exclusion allows only one thread to hold a particular lock at a time, so you can use this attribute to implement a coordinated access protocol to shared data so that only one thread at a time can use the sha

deleted, causing the data phantom. that is, "abnormal security" requires us to meet the following two requirements: 1 do not disclose any resources, 2 do not allow data corruption. So what's our solution? It is easy to solve the problem by using the Object Explorer mentioned earlier, lock resource management class can guarantee the resources will not leak, can refer to "clause 11" to deal with the solution of the self assignment problem. The resolut

-before B, and B happens-before C, then a Happens-before c.5. Thread Start rule: the Start () method of the thread object Happens-before every action on this thread. Volatile and synchronized four different points:1 granularity is different, the former is for variables, the latter locks objects and classes2 syn Blocking, volatile threads not blocking3 SYN guarantees three major characteristics, volatile does not guarantee atomicity4 syn compiler optim

. ： 　　 This guarantee says so if a sequence of writes happens in a certain order, then anyone reading those writes would see the M appear in the same order.One solution is to make sure this any writes that's causally related to all other be written to the same partition , this problem does not occur in a single copy set (single partition), only in partitioned (sharded) environments. Workaround: (1) A causal operation routed to the sam

deployments (in order to ensure availability, must be deployed multiple), the same data read and write, at the database level concurrent read and write does not guarantee the completion sequence, This means that the subsequent read request is likely to be completed first (read dirty data): (a) The first step in the write request A,a eliminated the cache (e.g. 1 in) (b) Step two of a to write the database, issue a modification request (e.g. 2 in) (c)

ensure availability, must be deployed multiple), the same data read and write, at the database level concurrent read and write does not guarantee the completion sequence, This means that the subsequent read request is likely to be completed first (read dirty data): (a) The first step in the write request A,a eliminated the cache (e.g. 1 in) (b) Step two of a to write the database, issue a modification request (e.g. 2 in) (c) The first step in the rea

to ensure availability, must be deployed multiple), the same data read and write, at the database level concurrent read and write does not guarantee the completion sequence, This means that the subsequent read request is likely to be completed first (read dirty data): (a) The first step in the write request A,a eliminated the cache (e.g. 1 in) (b) Step two of a to write the database, issue a modification request (e.g. 2 in) (c) The first step in the

ensure availability, must be deployed multiple), the same data read and write, at the database level concurrent read and write does not guarantee the completion sequence, This means that the subsequent read request is likely to be completed first (read dirty data): (a) The first step in the write request A,a eliminated the cache (e.g. 1 in) (b) Step two of a to write the database, issue a modification request (e.g. 2 in) (c) The first step in the rea

by the Undo_retention parameter is valid, this is the new function of 10g.sql> ALTER tablespace undotbs1 RETENTION GUARANTEE;sql> ALTER tablespace undotbs1 RETENTION noguarantee;Without guarantee, Oracle does not guarantee that the undo information can be stored for 900 seconds, and if the undo table space is insufficient, Oracle ignores the Undo_retention setti