oracle commit wait

When a blocking txn id for DDL wait event occurs on Oracle 11gR2, 11gr2txn This article is the original article, reproduced please indicate the source: http://blog.csdn.net/msdnchina/article/details/44726875 In a recent case (oracle db of version 11.2.0.4), we encountered the blocking txn id for DDL wait event. The cu

Tags: Oracle local write waitNote 1:TYPICALLYDBWR have to free up some buffers when you want to read something from the disk. During This process there is chances that you'll be a waiting for your local buffer (i.e blocks dirtied/invalidated by R session) to is written to disk. Duringthis time the waits is shown as local write waits.when you want to read the data from this disk, DBDW had to empty some buffer. During this process, you may experience wa

following is the location of the hot block: ① table Block ② index block, segment header block (free list), undo block, etc. (2) when a session needs to read a buffer while the buffer is being read from disk to memory by another session. read by other session naming wait events. buffer busy waits wait events are common when hot blocks exist in the database, This

Oracle finds the SQL statement that causes the wait according to v $ wait_chains Oracle finds the SQL statement that causes the wait according to v $ wait_chains Functions of several views, from official documentsV $ sqltextV $ SQLTEXTDisplays the text of SQL statements belonging to shared SQL cursors in the SGA.V

How to quickly find the lock wait in the Oracle database In a large database system, to ensure data consistency, the system locks data when operating the data in the database. These locks include read-only locks, exclusive locks, shared exclusive locks, and other types, and each type has row-level locks (one record is locked at a time ), "Page-level locks" (one page is locked at a time, that is, the minimum

Repeat the library cache lock wait event in Oracle 11 GB, 11 glibrary From the example below, we can see that re-Compilation of objects in the production database will lead to library cache lock, so we should try to avoid compiling objects during business peaks. If a package or complex dependency exists in the process, it can easily lead to library cache lock. Therefore, you should also pay attention to thi

, SUBSTR (terminal,1,7), v$session.sid,v$session.serial#, V$session.machine from V$locked_object,all_objects,v$session WHERE v$locked_obje CT.OBJECT_ID=ALL_OBJECTS.OBJECT_ID and V$locked_object. Session_id=v$session. SID----ERP----------------------------------ERP /* If there is a lock waiting, you need to find out who caused the wait */ SELECT/*+ Rule */Lpad (", Decode (L.xidusn, 0,3,0)) | | L.oracle_username user_name,

Tags: db file sequential read for Oracle wait eventDB file Sequential read:Website Explanation:This event signifies, the user process is reading a buffer to the SGA buffer cache and is waiting for a physical I/Ocall to return. A sequential read is a single-block read.The single block I/Os is usually the result of the using indexes. Rarely, full table scan calls could get truncated to a single block call bec

. According to the event name, this is a wait event related to the resource management area. After querying metalink, it is found that if the system resource management area is set to the status of INTERNAL_QUIESCE, all users other than SYS and SYSTEM will be in this waiting event and cannot perform any operations. The Metalink Document ID 396970.1 describes this phenomenon. However, there are several differences with the problem description. First, t

, then examine the session waits for DBWR to see whether there is anything delaying DBWR. If this event occurs frequently, check whether the session waits for DBWR to see if there is any delay DBWR. Explain:When a session reads chunks of data from disk into memory, it needs to find free memory space to hold the blocks.This wait occurs when there is no free space in the memory;When a session is doing a consistent read, it needs to construct a pre-image

In a RAC environment, logging into an instance can result in a GC global wait generation when the data being processed is completely unrelated to the data in the other instance's memory. This article describes the performance impact. The previous article describes the phenomenon of GC wait, and this article verifies whether the resulting global wait can adverse

Tags: Oracle wait EventInstance-level monitoring, open and low overhead:To create a base table:Createtablesys.sesstat_historytablespaceeolas SELECTc.username, c.osuser, a.sid, c.serial#, NBSP;NBSP;NBSP;NBSP;NBSP;NBSP;NBSP;C.PADDR, c.process, c.logon_time, a.statistic#, b.name, a.value, sysdateaslogoff_timestamp fromv$sesstata,v$statnameb,v$sessionc WHERE1= 2 Createtablesys.session_event_historytablesp

DB file Parallel readWebsite Explanation:This happens during recovery. It can also happen during buffer prefetching, as an optimization (rather than performing multiple single-block reads). Database blocks, need to being changed as part of recovery is read in parallel from the database.Wait Time: Wait until all of the I/Os is completed650) this.width=650; "src=" Https://s1.51cto.com/wyfs02/M01/8F/82/wKioL1jjQhXA72qRAAAfXjFTnto826.png "title=" 1.png "a

Ext.://http://blog.chinaunix.net/uid-23177306-id-2531235.htmlFirst, direct path read1. Wait events associated with direct read. When Oracle reads data blocks directly into the PGA (Process Global Zone) of the session, it bypasses the SGA (System global Zone). Data in the PGA is not shared with other sessions. That is, this part of the data read is used on its own, not in the shared SGA.2, when the sort oper

DB file Scattered read For frequently accessed tables, if an index is not indexed or an appropriate index is not established, Oracle can only scan it for a full table, resulting in a large number of waiting events. When a full table scan, the data read is generally contiguous on disk, but is not contiguous when read to memory, so the event is named discrete read (scattered read), and be careful not to be fooled by its name. The number of multiple-b

be greater than 1) On a healthy system, physical read waits should is the biggest waits after the idle waits. However, also consider whether there is direct read waits (signifying full table scans with parallel query) or DB file sc Attered read waits on a operational (OLTP) system that should be doing small indexed accesses.Other things this could indicate excessive I/O load on the system include the following: Poor Buffer Cache Hit ratio These

Tags: select from AST STR index operation ext ATT statement1. Cause of production This wait event typically occurs when the database is read in chunks, indicating that there is a wait associated with a full table scan and a quick index scan . This usually means too many full-table scans, or insufficient I/O capabilities, or I/O competition. 2. Determine the method of generating the problem object A) The SQL

1. The function and influence of the lock Locks are one of the core mechanisms for Oracle to manage concurrent access to shared database resources and to prevent "mutual interference" between concurrent database transactions. When the application system is complex and the volume of traffic is large, the lock wait phenomenon before the application process often occurs, which affects the normal operation of

In a RAC environment, logging into an instance can result in a GC global wait generation when the data being processed is completely unrelated to the data in the other instance's memory. This article describes a phenomenon. The environment is as follows: Sql> Conn YANGTK/YANGTK is connected. Sql> select * from V$version; BANNER ---------------------------------------------------------------- Oracle