wait event

The story of Ash and awr1.1 About AshAs we all know, when a user performs an operation in an Oracle database, it is necessary to create the appropriate connection and session, where all current session information is saved in the dynamic performance

Vernacular once, simple can be divided into two steps to find 1. Select Kgllkses saddr,kgllkhdl handle,kgllkmod mod,kglnaobj ObjectFrom X$kgllk lock_awhere Kgllkmod > 0and exists (select 1 from X$kgllk lock_bwhere Kgllkses in (select Saddr from

The SCN propagation mode of BOC is only propagated when the SCN of a node changes, and the LGWR process works in conjunction with the LMS process to synchronize the SCN,LGWR between nodes to write redo information to the Redo log file and send the

Oracle has a parameter when creating a sequence (sequence) you can choose either cache or NoCache, and here's the difference:First look at the statement that creates the sequence:Create sequence seq_idMinValue 1MaxValue 99999999Start with 1Increment

One: SQL tuning class1: List Several table connection methodsHash Join/merge join/nest Loop (cluster join)/index join2: How to view SQL execution plan without third-party toolsSet Autot onExplain plan set statement_id = &item_id for &sql;SELECT *

The basic Oracle performance optimization methods include the following steps: 1) set up a reasonable Oracle performance optimization goal. 2) measure and record the current Oracle performance. 3) determine the current Oracle performance bottleneck (

Oracle server processIn the process of completing a user process request, the following seven tasks are completed: 0. SQL statement parsing; 1. the data block is read into the database buffer and written to the data cache); 2. logs; 3.Create

Usage conditions: For Linux or Solaris machines, doulebuffercache is recommended in AWR. dbfilesequentialread is topwaitevent. The size is 2-10 times the bufferc size. Usage conditions: For Linux or Solaris machines, we recommend doule buffer cache

At that time, the customer asked for help, the database status is not normal, connected to the database can not operate normally, and sometimes error ORA-12537 error. ORA-12537: TNS: connectionclosedCau At that time, the customer asked for help, the

When the data block in buffercache is modified, the server process generates redo data and writes it to redologbuffer. When the following conditions are met, LGWR will When the data block in the buffer cache is modified, the server process generates

I recently read several pages of books, take notes, and copy a paragraph from the official oracle documents. Of course, BufferCache is far more than that, but reading English is really slow. Now I want I have read several pages of books recently,

How does an Oracle service process a user process? the server process completes the following seven tasks during the process of completing a user process request: 0. SQL statement parsing 1. Data Block How does an Oracle service process a user

Ucos ii event control block learning time: Source: Author: Mike Zhong CLICK: 1940 I. Data Structure of the Event Control Block ECB: Typedef struct{Int8u oseventtype; // event typeInt8u oseventgrp; // the group in which the waiting task is locatedInt1

C: \ Users \ Administrator> impdp boss/boss directory = dir dumpfile = out-% u. dmp remap_schema = BOSS: Boss remap_tablespace = nnc_data01: Users remap_tablespace = nnc_data02: UsersRemap_tablespace = nnc_data0 3: usersremap_tablespace = nnc_data04:

In many cases, you can use SQL tracking to diagnose the performance of a database and record some information in the trace file for further analysis. In general, we can set SQL tracking by initializing the parameter SQL _trace = true. We can also

There are three common cases of slow Database1. Slow down2. Sudden slowdown3. Slow down from time to timeIn the first case, a long-term monitoring mechanism should be established to "gradually slow down. For example, when writing a shell script

-- Obtain the current session ID under PL/SQL delover command Select sys_context ('userenv', 'sid') Sid from dual; -- start the 10046 trail Alter session set events '2014 trace name context forever, level 12'; -- declare Type type_owner is table of

How to diagnose cursor pin s wait on x Series 1, cursorpinFirst, clarify one thing: cursor pin s wait on x is the symptom (result), not the root cause.Mutex related wait event "cursor: pin S wait on X"General cause:Frequent and hard parsing (High

About Oracle 10 Gb performance, the most talked about is the new automatic workload repository (AWR) features and proactive performance monitoring through automatic database Diagnostic Monitoring (ADDM. They are widely reported as an alternative to

poll mechanism function: the equivalent of a timer, the time has not yet the resources to wake up the process.The main purpose is: The process is set up for a period of time to wait for resources, if the time to the resource has not arrived, the