可以发现不添加任何参数建表时,其ITL事务槽默认有两个,也就是不论initrans参数是1或者是2,一个BLOCK的事务槽数量至少为2。观察其构成,XID对应回滚段中对应的事务xid,Uba对应回滚段地址,flag对应当前的事务状态,以及最后的事务SCN。 那什么原因会导致enq: TX - allocate ITL entry等待事件呢? INST_ID USERNAME SI...
Event Waits Time(s) Avg wait (ms) % DB time Wait Class enq: TX - allocate ITL entry 1,200 3,129 2607 85.22 Configuration DB CPU 323 8.79 gc buffer busy acquire 17,261 50 3 1.37 Cluster gc cr block 2-way 143,108 48 0 1.32 Cluster gc current block busy 10,631 46 4 1.24 Clust...
WHERE DBMS_ROWID.ROWID_BLOCK_NUMBER(ROWID)=94954 AND DBMS_ROWID.ROWID_ROW_NUMBER(ROWID)=3; 会话1出现了等待。 会话3: UPDATE T_ITL_LHR SET A=A WHERE DBMS_ROWID.ROWID_BLOCK_NUMBER(ROWID)=94953 AND DBMS_ROWID.ROWID_ROW_NUMBER(ROWID)=3; 会话3发现出现了等待。 我们查询阻塞的具体情况: SELECT...
1 255 TRANS_TEST In earlier releases, theMAXTRANSparameter determined the maximum number of concurrent update transactions allowed for each data block in the segment. This parameter has beendeprecated.Oracle now automatically allows up to 255 concurrent update transactions for any data block, depending...
TX - allocate ITL entry By default the INITRANS value for a table is one, and for an index is two. This defines an internal block structure called the Interested Transaction List (ITL). In order to modify data in a block, a process needs to use an empty ITL slot to record that the...
[20220228]enq TX - allocate ITL entry的测试3.txt --//上个星期的测试有点乱,重新规划测试. 1.环境: SCOTT@book> @ver1 PORT_STRING VERSION BANNER --- --- --- x86_64/Linux 2.4.xx 11.2.0.4.0 Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production create table t ...
注2:INITRANS不足的问题不会出现在索引数据块上,当发现没有足够空间分配ITL slot时,无论是枝点块还是叶子块,数据块会发生分裂(Index Block Split)。MAXTRANS不足。当受到MAXTRANS限制时,也会发生此类等待。MAXTRANS的默认值是255(10g以后则不能修改这一参数),但是其实际大小是受到块的大小的限制的。ITL Slot占用...
来看看是否有top的等待事件,对于其它的几个等待事件都很熟悉了。有些问题早已进行了建议,还在修改中,但是对于第3个等待事件"enq: TX - allocate ITL entry"还是比较陌生的。准备来做一个深入的分析。 因为得到的是最新的awr报告。所以就在sqllplus上简单排查了一把。可以看到有两个session都持有这个等待事件。
taken in the free space reserved in the block. If this runs out and too many concurrent DML transactions are competing for the same data block we observe contention against the following wait event - "enq: TX - allocate ITL entry".
theMAXTRANSparameter determined the maximum number of concurrent update transactions allowed for each data block in the segment. This parameter has beendeprecated.Oracle now automatically allows up to 255 concurrent update transactions for any data block, depending on the available space in the block....