another session

1. The difference between for update and for update nowait:First of all, if only select, Oracle will not add any lock, that is, Oracle to select read the data there is no limit, although it is possible that another process is modifying the data in

The cursor modification and deletion operations refer to modifying or deleting the specified data rows in the table under the cursor positioning. In this case, the FORUPDATE option must be used in the cursor query statement to lock all the columns

Oracle temporary tables can be said to be a good way to improve the performance of database processing, stored only in the Oracle temporary table space when there is no need to store them. Hope this article can be helpful to everyone. 1. Preface

A further step, for everyone to test, if manually the buffer header buffer pin memory bit set to 1, which is equivalent to adding a shared buffer pin lock, then another session, update this block, what will happen? 1, take T1 table of the first row

In the field of open source database, PostgreSQL is well-deserved for its superior performance, function and good stability, especially for high concurrency support. and superior performance and stability, it is nothing but a good infrastructure,

Concept IntroductionDevelopers like to use with (NOLOCK) in SQL scripts, with (NOLOCK) is actually one of the table hints (table_hint). It is equivalent to readuncommitted. The specific function functions are as follows (from MSDN):1: Specifies that

Concept IntroductionDevelopers like to use with (NOLOCK) in SQL scripts, with (NOLOCK) is actually one of the table hints (table_hint). It is equivalent to readuncommitted. The specific function functions are as follows (from MSDN):1: Specifies that

Buffer busy waits (Hot block contention)Website Explanation:This wait indicates that there is some buffers in the buffer cache that multiple processes is attempting to access C oncurrently. Query V$waitstat for the wait statistics for each class of

If you use a SET TRANSACTION statement, then it must is the first statement in your transaction. However, a transaction need not has a SET TRANSACTION statement.Syntaxset_transaction::=http://docs.oracle.com/cd/B28359_01/server.111/b28286/statements_

Concept IntroductionDevelopers like to use with (NOLOCK) in SQL scripts, with (NOLOCK) is actually one of the table hints (table_hint). It is equivalent to readuncommitted. The specific function functions are as follows (from MSDN):1: Specifies that

The following is primarily about Oracle 10g bitmap indexing, with a focus on Storage, other advantages and disadvantages, query mechanism is also introduced slightly, because the storage mechanism is the foundation of . The content is mainly

Concept IntroductionDevelopers like to use with (NOLOCK) in SQL scripts, with (NOLOCK) is actually one of the table hints (table_hint). It is equivalent to readuncommitted. The specific function functions are as follows (from MSDN):1: Specifies that

Here do not repeat the installation of the 5.7 steps, the main attention to the initialization method and configuration files, with a lot of changes, while the 5.7 enhanced security, the initialization will give a password, the first time to change

Online modification of table object structure: Before MySQL5.6 1. Create a temporary table with the same structure as the original table object (invisible to users in implicit operations) and structure the table Online modification of table object

The view v $ session_wait can be used to view the current wait events of the system and related information of resources corresponding to the wait events. The view v $ session_wait can be used to view the current wait events of the system and

The following articles mainly describe the practical experience of using temporary Oracle tables correctly. The proportion of temporary Oracle tables in practice is still the majority. If you use this technology, if you are curious, the following

Oracle copy tables, temporary tables, and viewsCreate a new_table table with the same structure as the old_table Table (no old_table Records) Create table new_table as select * from old_table where 1 = 0; Create a new_table table with the same

MySQL Stored Procedure Transaction Management and mysql Stored Procedure transaction  ACID: Atomic, Consistent, Isolated, Durable A storage program provides an excellent mechanism to define, encapsulate, and manage transactions. 1. MySQL

Mysql supports transaction processing starting from 41, but transaction operations are supported only for databases created by engines of the InnoDBBDB type. View the mysql database Creation Engine type: showcreatetabletable_name Mysql supports

In 10 Gb, enqueueTX waits for four types: 1.enq: TX In 10g, enqueue TX waits are divided into four categories: 1. enq: TX-row lock contention 2. enq: TX-index contention 3. enq: TX-ITL 4. enq: T In 10g, the enqueue TX wait is divided into four