Row cache lock 19c. 2中体现的等待事件为：”library cache lock”。 .

Row cache lock 19c 文章浏览阅读883次，点赞20次，收藏9次。通过如下分析是由于故障时段有大量硬解析，硬解析需要去获取数据字典资源，这需要获得latch，若硬解析量太大，会造成严重的latch争用，占用非常多的资源，导致CPU使用过高，从而表现出数据库ROW CACHE OBJECT等待事件，最终导致数据库系统缓慢。 1 if High waits on “row cache mutex” when looking up user or role information in user row cache (dc_users). 7。周日业务反应有大量业务阻塞，通过一线同事发来的wait chain信息可以看到大量的row cache lock(CID=16)和library cache lock，并且final blocking event是row cache lock。final block session是not wait的。. 12cR2 introduced "row cache mutex" to replace previous "latch: row cache objects". Unfortunately, there is a whole raft of things that could be the cause, eg - Excessive use of row level triggers - Excessive Amount of Child Cursors (multiple plans, bugs etc) 这种现象在Oracle 10. Applies to: Oracle Database - Enterprise Edition - Version 9. DM. Resolving Issues Where 'enq: TX - row lock contention' Waits are Occurring (Doc ID 1476298. To view full Resolving Issues Where 'Row Cache Lock' Waits are Occurring (Doc ID 1476670. 1 and later Oracle Database Cloud Schema Service - Version N/A and later ORA-445 and Heavy 'latch: shared pool' and 'row cache *' Waits; RAC may Hang (Doc ID 2954678. lots of requests for mutex on user$ row cache, may hit Bug 30623138. High library cache lock waits post upgrade to 19C during global 前言 最近看 awr 报告时，经常会看到一些 enq: TX - row lock contention 的等待事件，所以简单研究一下如何排查，仅为个人所见，如有异议或者修正还请评论指出，谢谢！. This is used to control concurrency between clients of the library cache by acquiring a lock on the object handle. 1. VARCHAR2(4) LOCK or PIN. Applies to: Oracle Database - Standard What is the meaning of the warning WAITED TOO LONG FOR A ROW CACHE ENQUEUE LOCK? Potential reasons for "WAITED TOO LONG FOR A ROW CACHE Explore the causes and solutions for Oracle row cache lock wait events. The SQL i 而请求的row cache lock类型是dc_users型enqueue ，并且请求对象的地址为【c0000003786fd3a0 】。 关于’row cache lock’ row cache lock是对共享内存（Shared pool）中数据字典信息（dc_XXX）进行操作时，加载的 Enq: TX – Row lock contention This type of event is application level locking problem that occurs when a user session is trying to update or delete a row held by another session, which is an application. 16. Hello, The database on one of 4 nodes started to hang. 4 and later row cache lock 10 2 2838 23 CENTERNEW row cache lock 10 29 CENTERNEW row cache lock 10 2 2838 26. Optimize your database performance—read the full guide now! row cache lock等待事件是一个共享池相关的等待事件，是由于对于字典缓冲的访问造成的。通常直接的解决办可以通过调大共享池来解决，但是，并非在所有场景下都凑效。 Getting a library cache lock on the table and a row cache lock on the dc_histograms cache is a prerequisite for changing the column statistics. The enqueue lock structures are allocated from the shared pool as needed but when these I’ve been seeing this issue after upgrading to 18c, but I’ve managed to reproduce it on 12c and 19c as well. 4. Undo segment DDL. Top 10 Foreground Events by Total Wait Time. The enqueue lock structures are allocated from the shared pool as needed but when these This is more likely to be seen in an OLTP environment where both shared pool and buffer cache are in demand. 1) Last updated on SEPTEMBER 10, 2024. 产生library cache lock的原因通常有三种：登录密码错误尝试过多、热表收集统计信息和SQL解析失败。而索引重建会引起统计信息变化，统计信息变化引起SQL重新解析，并且表uxxxxxxr是该数据库上的核心表之一，也是该库的热表，使用主键访问表uxxxxxxr又是一个热点行 the user X row cache lock is held in exclusive mode preventing 19C BACKUP/RECOVERY DataGuard dblink exadata Goldengate HAIP lob mysql oceanbase OGG ora-600 ORA-1017 ORA-4031 ora-7445 ORACLE11g oracle 12. 2中体现的等待事件为：”library cache lock”。 Significant increase in library cache: mutex x wait time after upgrading database to 19c (Doc ID 32356628. Direct loader parallel index create. 14 RAC 4-nodes, After the database was upgraded to 19c, there was a performance problem. 4 과(와) 그 후속 Troubleshooting Steps wait: library cache lock Cause Identified: Unshared SQL Due to Literals Solution Identified: Rewrite the SQL to use bind values Solution Identified: Use the CURSOR_SHARING initialization parameter Cause Identified: Shared SQL being aged out Solution Identified: Increase the size of the shared pool Solution Identified: 10 g+: Use the Finding 2: Row Lock Waits; 应用确认; 写在最后; 前言. 1) Last updated on JULY 20, 2024. log file parallel write. 3 row cache lock事件 --内存share pool分为library cache,dictionary cache;而row cache lock对象分布在dictionary cache中； --每次看到类似的告警短信心理都比较发毛；这类属于latch类的资源竞争，相当耗CPU，如果并发量大的话，容易down机 先模拟一个场景：原理，建立一个 A rather odd performance issue happened at work a few days ago. 4 Concurrency The shared pool contains a cache of rows from the data dictionary that helps reduce physical I/O to the data dictionary tables and allows locking of individual data dictionary rows. 0 and later Oracle Database Exadata Express Cloud Service - Version N/A and later Version: 19C. 3, 1979, introduced rule-based optimizer，Cost-Based Optimizer introduced Oracle 7. Applies to: Oracle Database - Personal Edition - Version 9. I will explain Enq: TX – Row lock contention Wait Event in Oracle Database in this post. 1) Last updated on MARCH 05, 2025. Library cache pin waits. Below are the scripts for finding the sessions holding libary cache lock: For standalone db: Heavy "row cache lock"(dc_constraints) and "enq: TX - allocate ITL entry" waits occur in the database, hanganalyze trace might show deadlocks, both of the holder and the waiter are creating a table. 通常，产生enq: TX - row lock contention事件的原因有以下几种可能： 不同的session更新或删除同一 Database 19c Multitenant with Database Vault: Changing password for common user hangs, waiting on Concurrency row cache lock. 1) Last updated on JULY 18, 2019. Cause #7: Extensive use of row level triggers Solution: Evaluate the need for the row trigger; Cause #8: Excessive Amount of Child Cursors Solution: Inappropriate use of parameter CURSOR_SHARING; Find Sessions Holding Library Cache Lock. A library cache lock means that some sessions are competing over a common resource in the library cache. Event Waits Total Wait Time (sec) Avg Wait % DB time Wait Class row cache lock 1,212 112. 7. Average wait time. The new 19c latch "SO private so latch" is positioned in LEVEL#=9, and "shared pool" latch LEVEL# is increased to 10 from 7 in 18c (latch ordering rule: Once a process acquires a latch of level x, it can only acquire another latch of level higher than x). This event involves writing redo records to the redo log files from the log buffer. 1) Last updated on AUGUST 26, 2024. 86 s 43. 8) Bug 32219835 - Performance Degraded with Library Cache: Mutex x with latch: row cache objects; latch: session allocation; latch: shared pool; latch: undo global data; library cache: bucket mutex X; library cache load lock; library cache lock; library cache: mutex X; library cache pin; library cache shutdown; local write wait; lock manager wait for remote message; log buffer space; log file parallel write; log A few minutes later the same user started running Create table in session 596, table name is the same as in session 11909. High concurrency waits on 'row cache lock', library cache lock','cursor: pin S wait on X'. Recently, a customer’s Oracle database encountered a performance problem, waiting for “row cache lock”. At first, we 本站中文解释Oracle事件row cache lock是指独立的应用程序或会话正在更新或查询表中的行时，另一个会话想要访问同一行时可能会遇到的等待。 它多发生在围绕非索引列的更新或查询操作的情况中，因为行缓存锁是Oracle在用户会话进行此类操作时尝试获取的选择锁。 The shared pool contains a cache of rows from the data dictionary that helps reduce physical I/O to the data dictionary tables and allows locking of individual data dictionary rows. 0. Redo thread global enqueue. 1 and later Gen 1 Exadata Cloud at Customer (Oracle Exadata Database Cloud Machine 19. The row cache objects latches protect the data dictionary. 1) Last updated on JULY 05, 2024. From AWR, I saw a large number of library cache locks and library cache pins in the top event. The problem will happen randomly and intermittently. In this Blog, we will choose 'dc_props' and 'dc_cdbprops' to test "row cache mutex". DL. datafile instance. As per this bug: In 11g there is an intentional delay between allowing failed logon attempts to retry. Viewed 1000+ times You Asked . Waits on this event usually indicate some form of DDL occurring, or possibly recursive operations such as storage management and incrementing sequence numbers. The respective SQL statement is one of the frequently running statement (15,000 times per minute) in the application. 4 and later Oracle Database - Enterprise Edition - Version 8. 17. The call stack from the hang analyze trace indicates a potential bug. Sign In: To view full details, sign in While working on a recent problem, I missed a possibility of tracing library cache locks. Database was hung / slow and had to be re-started for the issue to be mitigated. 0 and later Information in this document applies to any platform. RAW(4 | 8) User session holding this lock/pin Multiple sessions requesting a nextval will hence be blocked on a ‘row cache lock’ wait. Certain indexes are causing a high percentage of buffer busy waits, row lock waits, and ITL waits. fix in 19. The AWR shows as ‘Waiting for event 'library cache lock' in wait class 'Concurrency'’. 1 and later Oracle Database - Personal Edition - Version 9. RAW(4 | 8) Address of the lock/pin. 适用于: Oracle Database - Enterprise Edition - 版本 8. The following statistics are affected by this change: Wait counts. 8 2. 从11. 2之后如果是密码错误导致的密码延迟一般产生的是library cache lock，这里发现有很多session username是空的，这就说明是那些登录异常的session，都是等待row cache lock，通过p1可以判断是dc Database hang or very slow performance with high contention on wait event 'row cache lock' in 12. Oracle 19c lock types. The issue still happens even after applies the fix for Bug 13869467 as documented in (Doc ID 13869467. Reasons for the Library lock contention 另外一个等待事件cusor: pin S wait on X，这个等待事件是某个会话需要申请S模式的mutex，而mutex被其他会话以X模式占有了，当前会话会处于cusor: pin S wait on X等待事件，结合这些会话的阻塞会话发现，阻塞会话全部是row cache lock等待事件的会话，所以说根本原因是row cache lock导致的。 On : 11. DDL Locks DDL locks protect the definition of schema objects while ongoing DDL operations acts on or refer to the objects. MM. 1 introduced online statistics gathering for 1. 1中体现的等待事件为：”row cache lock”，而在Oracle 11. namespace 最近遇到这个案例大量FG prorcess堵塞，19c (19. ADDR. For some specific application types this can cause a 上关于row cache lock的所有日志聚合 信春哥，系统稳，闭眼上线不回滚！ 为方便朋友们互相交流、批评、指正，增加了QQ即时聊天功能，大家共同学习，共同进步。 Latch: The cache buffers chains and buffer busy waits contribute to this issue. 1) Last updated on JULY 31, 2024. Run dynamic call for 10 executions, and trace kglLock mutex Request/Release with appended "gdb_script_mutex When encountering the Enq: TX - row lock contention wait event, it's crucial to identify the root cause before taking action. 2 ORACLE 12C ORACLE ADMIN ORACLE ADMIN oracle asm oracle dataguard oracle goldengate oracle internal oracle oem 点1的活动会话已接近4000，几乎全是Library cache lock的会话，blocker session 在等待DFS lock handle ，当shared pool里的对象需要为新的对象释放空间时如sql cursor, LCK进程降低Row Cache 大小期间使数据库临时hang， 因为在RAC环境中LCK进程负责释放持有row cache的用户进程协调工作 This action caused library cache lock, cursor: mutex S, and library cache: mutex X wait events when the cursor invalidations happens due to DDL on an object used in the SQL. All of a sudden, one of the databases started to work very slowly, and a quick look in ASH data showed that it was spending over 70% of its time waiting on "row cache lock" if High waits on “row cache mutex” when looking up user or role information in user row cache (dc_users). 4 和更高版本 另外一个等待事件cusor: pin S wait on X，这个等待事件是某个会话需要申请S模式的mutex，而mutex被其他会话以X模式占有了，当前会话会处于cusor: pin S wait on X等待事件，结合这些会话的阻塞会话发现，阻塞会话全部是row cache lock等待事件的会话，所以说根本原因是row Row cache lock ??? After searching on MOS I found following note : Bug 7715339 – Logon failures causes “row cache lock” waits – Allow disable of logon delay (Doc ID 7715339. The row cache lock was acquired for deleting the Row cache instance (A. 2; The High Contention on 'row cache objects' could be on Dictionary Cache for objects "dc_users" or "dc_tablespaces" Systemstate or Hanganalyze dumps show that the waiting process Call Stack Waits for the Waiting Process on "row cache lock" event: The row cache lock is used primarily to serialize changes to the data dictionary and is waited on when a lock on a data dictionary cache is required. 極端な例では、まったく動きがなく、データベースがハングアップしたように見え、"waited too long for a row cache enqueue lock!" のようなタイムアウト関連の症状になる場合があります。次を参照してください。 Row Cache 或 Data Dictionary Cache 是共享池中的一个内存区域，用于保存数据字典信息以减少数据字典表的物理 I/O。行高速缓存锁主要用于序列化对数据字典的更改，当需要对数据字典高速缓存进行锁定时，将等待该锁,数据字典行上的锁称为row cache lock。 For example, table locks and row locks. The issue resulted in an outage, with sessions waiting indefinitely on 'row cache lock' and 'enq: TX - row lock contention' events. HOLDING_USER_SESSION. 1) Last updated on NOVEMBER 03, 2024. RT. Both have a fixed number of objects, a fixed pattern to use mutex for each object access, so that test can be repeated, and results are identical for each run. High concurrency waits on 'row cache lock' and 'cursor: pin S wait on X' while the blocker is waiting for 'Disk file operations I/O' on a password file. Changes. Workaround. 0 – Production Coordinates updates and accesses to row cache objects: RA: Real-Time ADDM Flood Row cache lockの競合が最も頻繁に発生する場合は、NOCACHE属性のシーケンスです。キャッシュを使用していないシーケンスは、次の値（NEXTVAL）を呼び出すたびにディクショナリ情報を変更する必要があり、この過程でRCOについてrow cache lockをSRX（5）モードで獲得しなければなりません。 How to Diagnose Issues Where 'enq: TX - row lock contention' Waits are Occurring (Doc ID 1986832. 最近看 awr 报告时，经常会看到一些 enq: TX - row lock contention 的等待事件，所以简单研究一下如何排查，仅为个人所见，如有异议或者修正还请评论指出，谢谢！ 通常，产生enq: TX - row lock contention事件的原因有 From ORA-00060 trace file, INDEX rebuild session was blocked by session sid: 6027 and waiting for 'library cache lock' of the table of this index, and held row cache lock of dc_objects and was blocking session sid: 6027: 1 数据库性能最佳实践 使用连接池和绑定变量减少硬解析 业务高峰期，尽量避免实行DDL •一个简单的GRANT语句都可能会一起性能问题。•执行DDL后会引起相关的SQL在共享池中的失效，当相关SQL再次并发执行，可能会导致硬解析风暴，从而引起“ library cache lock”, “row cache lock”, “cursor: pin S wait on X 4. AWR report. Row Cache Object and Row Cache Mutex Case Study about Row Cache "BUCKET mutex"). Uses are (a)One client can prevent other clients from accessing the same object (b)The client can maintain a dependency for a long time (no other client can change the object). 4) 2nodes RAC, 等待Library Cache Load Lock， 最终的堵塞会话为REC0 后台进程， 该进程等待gc cr block lost. 环境oracle 19c(19. Hanganalyze dump. 19c Library Cache Locks and Pins At first, we run query below to list meta info of PLITBLM and our two test procedures in library objects of 19c DB. 1 and later Oracle Database - Enterprise Edition - Version 9. Information in this document applies to any platform. Note: Tested in Oracle 19c. 1. 如果一个库缓存对象（如一条SQL语句的执行计划），它所占的内存被切割成4个小块 环境oracle 19c(19. 1) Last updated on DECEMBER 14, 2020. Row cache lock waits. P = namespace) US. Under the approval of Oracle Support, you can try to change below parameter value from 15 mins to longer time. 8 19c Database Hung With ORA-04022 Errors and High Row Cache Lock Waits During Heavy Load (Doc ID 3043192. 4 과(와) 그 후속 Oracle Database - Personal Edition - 버전 8. 4 rac 出现大量等待事件：row cache mutex / pin S wait on X ，awr在附件 kqrGetClusterLock - kernel query dictionary/row cache get a row cache lock in cluster mode (cluster version of kqrget) kqreqd - kernel query dictionary/row cache enqueue delete. 1) C. 4 version, RDBMS, sessions hang on "row cache lock" (dc_objects) while creating & dropping a table concurrently; Session hang on "row cache lock" (dc_objects) in mode 3 (S mode) and the row cache objects shows "LOADING" status and complete flag is FALSE The database parameter "recyclebin" is default value (on) Changes. This issue may occur when changing passwords for Database Vault Owner or Account Manager, but it is also occurring for C## common users. There were some SQL with high execution rate observed which were creating a new child cursor for every execution and the version count report showed high version counts Troubleshooting 'library cache: mutex X' Waits. Wait time outs. 588816+00:00 >>> WAITED TOO LONG FOR A ROW CACHE ENQUEUE LOCK! pid=58 这种现象在Oracle 10. 2. 5K 92. 1) Last updated on SEPTEMBER 28, 2020. 0 - 64bit Production and my db had freezed after an hour i got in alert Waited too long for a row cache enqueue lock! PID=xx three times, in tra 有一点必须要注意，没有赋予 CACHE属性时，不管ORDER属性使用与否或RAC环境与否，一直等待row cache lock 事件。row cache lock是可以在全局范围内使用的锁，单实例环境或多实例环境同样可以发生。 Sometimes your Oracle database may hang, or Oracle Database hangs periodically with lots of sessions being blocked by each other, deadlocks can be seen as well, with different waits such as library cache lock cursor and ‘cursor: pin S wait on X’, ‘row cache lock’ and ‘library cache load lock’ and etc. Applies to: Oracle Database Cloud Schema Service - Version N/A and later Gen 1 Exadata Cloud at Customer (Oracle Exadata Database Cloud Machine) - Version N/A and later Oracle Cloud Infrastructure - Database Service - Version N/A and later Oracle Library Cache深入解析 每一个进入库缓存的对象，在库缓存中都被按照本身内容分割成多块进行存贮。Oracle这样做的目的是为了更灵活的内存管理，因为在内存寻找大块连续的内存，总比寻找小块连续内存更慢一些. Oracle 2. The problem was further investigated using ASH data and session history views. 8) Bug 32219835 - Performance Degraded with Library Cache: Mutex x with 19c Database Hang And/Or Deadlocks with Row Cache Mutex" And "Latch: Shared Pool" Waits (Doc ID 3036387. (kslgetl immediate_gets) is requested at first, which again requests library cache WAITED TOO LONG FOR A ROW CACHE ENQUEUE LOCK! Susan Yang Feb 8 2009 — edited Feb 9 2009. 1) Last updated on JANUARY 10, 2025. 7) on linux, 数据库做了failover后在open resetlogs数据库时，等待了很久的时间，数据库里查询wait event是’row cache lock’ & ‘cursor: pin S wait on X’， DB alert log显示下面的信息:可以看到不断的在输出TTnn Sleep 10 seconds and then try to clear SRLs in N time(s)， TTnn进程为异步模式下的REDO传输进程， 在清理 Column Datatype Description; TYPE. The locks on the data dictionary rows are called row cache enqueue locks. More than 24 hours later other sessions start experiencing waits on 'library cache lock' and 'cursor: pin S wait on X'. 적용 대상: Oracle Database - Standard Edition - 버전 8. 等待事件ROW CACHE LOCK基础说明ROW CACHE LOCK等待事件是一个共享池相关的等待事件。是由于对于字典缓冲的访问造成的。P1 – Cache IdP2 – Mode HeldP3 – Mode Requestedmode 和REQUEST的取值：KQRM 1. Applies to: Upgrade to 19c, and often 19. Symptoms. 4 and later Oracle Database - Standard Edition - Version 8. Enq: TX – Row lock contention This type of 在处理这个问题的时候，参照了老白的文章：白鳝说WAIT EVENT之ROW CACHE LOCK From OracleOnLinux, post 解决一则row cache lock引起的性能故障 点击阅读感兴趣的文章. In contrast, row cache locks can be traced with the event 10222: kqrpre: optimistic lookup: success kqrpre: done po=7fffbd990200 cid=8 flg=0 eq=0 pso=99184ec8 dur=CALL kqrpre: keyIndex=0 hash=162240d8 d53980ff 0 kqrpre: obobn=690 19790972 – “library cache lock” waits due to DBMS_STATS gather of stats for a sub partition. In extreme examples the database can appear to hang and you may receive related timeout symptoms such as "WAITED TOO LONG FOR A ROW CACHE ENQUEUE LOCK!" Errors in file /u01/app/oracle/admin/stormsid/bdump/stormsid_arc0_5144. Analysis showed that the cache# p1 value pointed to the dc_realtime_tabst 。. In fact, the purpose of this blog post is to provide a reproducable test case which might be useful for fixing the bug and explaining the circumstances leading to the problem. trc: Library cache lock in wait class Concurrency In the Production Application we randomly notice a hiccup (slowness) in the database. 1) Troubleshooting: "WAITED TOO LONG FOR A ROW CACHE ENQUEUE LOCK! " (Doc ID 278316. Oracle Database 19c Enterprise Edition Release 19. 2. 88 library cache load lock セッションは、データベース・オブジェクトをロードするためのロード・ロックの検索を試行します。 他のプロセスが同一のオブジェクトをロードできないように、ロード・ロックは常に排他モードで取得されます。 天萃荷净运维DBA反映巡检数据库时发现Oracle等待事件ROW CACHE LOCK，结合案例分析产生原因和解决办法案例1. The alert log file indicates "WAITED TOO LONG FOR A ROW CACHE ENQUEUE LOCK!" Does anyone have some insights as to the root cause and what to do for a trouble-shooting? What is library cache lock. (Doc ID 1357946. 3. For tables in the SYS schema only a Recently, a customer’s Oracle database encountered a performance problem, waiting for “row cache lock”. 1) Last updated on DECEMBER 24, 2024. 0 to 19. No changes. To resolve it, database administrators should pinpoint the blocking session and sql statement. In this Blog, we will look two types of dc_objects "row cache lock", one is Plsql program, another is table/partitions. 11. Maximum wait time. A detailed analysis of specific 本案例来自东区某客户，数据库版本为rac 19. Applies to: Oracle Database - Enterprise Edition - Version 19. Mount/startup db primary/secondary instance Library cache lock instance lock (A. System change number instance. . Each instance allocates numbers by access to the database but cache fusion may delay sending current seq$ block to a requesting instance if the block is busy owing to many sequence number allocations from the instance owning the current block image. WL. 適用範囲: Oracle Database Cloud Exadata Service - バージョン N/A 以降 Oracle Database Backup Service - バージョン N/A 以降 Oracle Database Exadata Express Cloud Service - バージョン N/A 以降 The environment is Oracle 19. And it only happens with Database Vault enabled, if DV is disabled the user The customer's database experienced row cache locks, leading to a complete database freeze, disrupting all application connections. 17 or higher. Mount definition global enqueue. Library Cache 诊断：Lock, Pin 以及 Load Lock (Doc ID 1548524. Test Setup. When concurrent sessions try to update optimizer statistics for the same object, all of them except the one that successfully acquired all necessary locks/pins on the library/row cache entries, wait on this wait event and then retry locking after a short period of time. 19c Database Hung due to High "row cache mutex" waits (Doc ID 2952129. Cause. No changes made. 'library cache lock' 대기 : 원인과 대처 방법 (Doc ID 2170579. This session waits on 'row cache lock', this is expected behaviour. 7) on linux, 数据库做了failover后在open resetlogs数据库时，等待了很久的时间，数据库里查询wait event是'row cache lock' & 'cursor: pin S wait on X'， DB alert log显示下面的信息:可以看到不断的在输出TTnn Sleep 10 seconds and then try to clear SRLs in N time(s)， TTnn进程为异步 现场同事告知oracle 19C 下生产大量trc文件，把oracle目录撑爆 查看trc文件如下 kqrpre: key mismatch po=0x132745948 hash=27d744ca SO: 0x12a9d2098, Resolving Issues Where 'Row Cache Lock' Waits are Occurring (Doc ID 1476670. 2和11. Applies to: Oracle Database - Personal Edition - Version 8. 8). 12,1992，Oracle database 12. 0 [Release 19] Oracle Cloud Infrastructure - Exadata Cloud Service - Version N/A and later High Library Cache Lock Waits After Upgrading To 19C During Partition Index Maintenance (Doc ID 2619066. Call stack from Hang analyze should look similar to below: Changes Cause 2022-06-20 09:20:20 row cache mutex 26 cursor: pin S wait on X 32 library cache: bucket mutex 36 latch: shared pool 40 2022-06-20 09:20:30 library cache load lock 46 latch: shared pool 50 library cache: mutex X 59 cursor: pin S wait on X 61 row cache mutex 62 I found MOS 33121934. Analysis showed that the cache# p1 value pointed to the Row cache mutex是数据字典缓存(row cache)中的内存锁，当多个进程访问row cache中的同一对象时，需要先获得这个对象上的mutex，才能进行访问（包括修改）。 Mutex以串行方式控制进程访问对象，当一个进程hold The shared pool contains a cache of rows from the data dictionary that helps reduce physical I/O to the data dictionary tables and allows locking of individual data dictionary rows. This contention arises when multiple sessions attempt to modify the same row in a table simultaneously. 8 Library cache lock / load lock / mutex x during Hi, i have Oracle9i Enterprise Edition Release 9. Z = cache) DF. row cache lock基础说明 row cache lock等待事件是一个共享池相关的等待事件。是由于对于字典缓冲的访问造成的。每一个行缓冲队列锁都对应一个特定的数据字典对象，这被叫做队列 'library cache lock' Waits: Causes and Solutions (Doc ID 1952395. 15. SC. 客户一套很重要的数据库，一直运行正常，一大早接到告警，发现出现大量的enq:SQ-contention和row cache lock等待事件，我们立马登上去做检查。出现这种情况，我们一般会先做hang analyze分析，找出堵塞的源头，进行杀掉阻塞的进程，然后堵塞会话会自行解开。客户一套很重要的数据库，一直运行正常 I was trying to duplicate a 19c database from an RMAN backup, but it was hanging at this final stage of opening the cloned DB in resetlogs mode: Analysis: When checked the alertlog I found the following messages in the alertlog: 2022-03-21T13:14:26. 'Row Cache Lock' 待機が発生している問題の解決 (Doc ID 2592358. 1) Last updated on JULY 10, 2024. April 10, 2012 -- 如何获取Oracle数据库中某表及索引、约束、触发器、对象权限的创建语句？ (0) ORACLE :11. ezmuw trl tuu axpd eagwk drqbm rclyxif blvet igrr hvldxc kwjk aue gaujg tgfkaec zeze