another session

In versions earlier than Oracle11, when a LOCKTABLE command is issued, if another session holds a lock on the table, it will wait for an indefinite period or wait directly. In versions earlier than Oracle 11, when a lock table command is issued, if

A long time ago, when I saw this section, I felt confused and semi-informed, because there were too many unfamiliar concepts. At that time, I also found some materials and blogs on the Internet. I felt that the help was not great, so I skipped it.

1) There are two rows in the statistics that are related to performance. 15 SQL*Net roundtrips to/from client 198 rows processed The first line indicates the number of rounds from buffer cache to PGA. The second row indicates the number of rows

If you 've ever gotten a phone call from an annoyed user whose transaction just won't go through, or from a developer who can't understand why her application sessions are blocking each other, you know how useful it can be to identify not just whose

Mysql timeout and mysqltimeoutMysql timeout ------ By bibimbap1. How much does the timeout variable know? Open mysql and useshow variables like '%timeout%'The command looks like I don't know, but I was shocked. The result is shown below. With so

The following is a description of the ORA-01555 from the online documentation Database Error Messages ORA-01555: snapshot too old: rollback segment number string with name "string" Too small Cause: rollback records needed by a reader for consistent

When sorting operations, re-indexing, and other large operations cannot be completed in the memory, the temporary tablespace will facilitate sorting. Generally, temporary tablespace is shared by multiple users and multiple sessions. The quota cannot

Oracle copy table, temporary table, and view, oracle copy table ViewCreate 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

Preface Currently, all applications that use Oracle as the database support platform have a large amount of data, that is, the data volume of tables is generally more than one million data volume. Of course, creating partitions in Oracle is a good

Temporaryqueue and temporarytopic can be seen literally as "temporary" destinations. You can create a session, for example:Temporaryqueue replyqueue = session. createtemporaryqueue ();Although they are created by sessions, their life cycle is indeed

It was interesting just now. First of all, when I invoice the customer. I have already set up. If the tax is collected, the money should be recorded in my ledger. The book says that the system should have several sales item tax rates for China's

Execute the dbms_redefinition.finish_redef_table stored procedure to relay the table online. . During this procedure operation, the original table will be locked in exclusive lock mode (Tm lmode = 6) exclusive lock mode. This is a very short period

Blog Source: http://www.cnblogs.com/kerrycode/p/3946268.htmlConcept 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

My understanding of the temporary table: Create a table in Oracle that doesn't need any other functionality, is used primarily for some specific features of its own software system, and is useless when you run out of data in a table. If you do not

(4th number Lock analysis of the unique key constraints) A previous customer suggested that when the insert was hang to live, the problem is likely to be locked. For such a question I usually think of a few common views:

In order to achieve maximum performance, the general database has concurrent mechanism, but the problem is the conflict of data access. To solve this problem, most databases use the method of data locking. Data locking is divided into two methods,

The using Backup controlfile is typically used to recover from a situation where the current control file is missing and the previously backed up control file is more than currently changed. Using Backup Controlfile Recover way once used, the

Reading notes db file scattered read DB, db file sequential read Db,free buffer waits,log buffer space,log file Switch,log file sync We can view the current waiting events in the system and the information about the resources corresponding to the

1. The temporary table's basic knowledge temporary table is supported only in oracle 8i  and above products. Oracle databases can also create temporary table temporary tables, in addition to saving permanent tables. These temporary tables are used

　Both logical and physical backups are strongly dependent on FTWRL (Flushtablewithreadlock) in order to obtain consistency sites. This lock is very lethal, because the whole database is essentially unable to provide write service to the time the