The BATCHED access shown in Step 1 means that the database retrieves a few rowids from the index, and then attempts to access rows in block order to improve the clustering and reduce the number of times that the database must access a block. 这句话的意思是说,该操作是数据库为了从索引中...
Oracle 12c引入的“TABLE ACCESS BY INDEX ROWID BATCHED”操作，旨在优化SQL语句执行计划。此操作意味着数据库在索引中获取若干rowid，随后尝试按块顺序访问数据行，以提升数据聚集性并减少对同一数据块的访问次数。这样，避免了在不同rowid对应数据行存储于同一数据块时，多次重复读取同一数据块的情况。以往...
该特性通过隐藏参数“_optimizer_batch_table_access_by_rowid”控制,默认值为true,即为开启。
Oracle12c开始,我们在获取SQL语句的执行计划时,也会经常看到"TABLE ACCESS BY INDEX ROWID BATCHED"操作,那么,这个操作到底是什么意思呢?有什么作用呢?下面我们先看看有关该操作的官方解释: The BATCHED access shown in Step 1 means that the database retrieves a few rowids from the index, and then ...
Oracle12c开始,我们在获取SQL语句的执行计划时,也会经常看到"TABLE ACCESS BY INDEX ROWID BATCHED"操作,那么,这个操作到底是什么意思呢?有什么作用呢?下面我们先看看有关该操作的官方解释: The BATCHED access shown in Step 1 means that the database retrieves a few rowids from the index, and then attem...
Oracle12c开始，我们在获取SQL语句的执⾏计划时，也会经常看到"TABLE ACCESS BY INDEX ROWID BATCHED"操作，那么，这个操作到底是什么意思呢？有什么作⽤呢？下⾯我们先看看有关该操作的官⽅解释：The BATCHED access shown in Step 1 means that the database retrieves a few rowids from the index, ...
Oracle 12c中新增通过ROWID BATCHED访问数据块的方式,优化原来使用单个rowid进行数据块访问方式带来的资源消耗及对数据块的扫描次数,即TABLE ACCESS BY INDEX ROWID BATCHED特性。该特性通过隐藏参数“_optimizer_batch_table_access_by_rowid”控制,默认值为true,即默认开启。
TABLE ACCESS BY INDEX ROWID BATCHED执行计划 SQL> set autot traceonly exp stat; SQL> var b1 number; SQL> set lines 150 SQL> set pages 10000 SQL> exec :b1:=18868701138; PL/SQL procedure successfully completed. SQL> SELECT BRAND_ID FROM T_USERTYPE_FULLNO WHERE BILL_ID= LTRIM(:B1 ,'0...
1 -access("D1"."OBJECT_ID"="D2"."OBJECT_ID") 统计信息 --- 1 recursive calls 0 db block gets 6353 consistent gets 0 physical reads 0 redo size 3388939 bytes sent via SQL*Net toclient 53874 bytes received via SQL*Netfrom client...
--//看看那些参数可以控制取消TABLE ACCESS BY INDEX ROWID BATCHED特性. 2.测试: --//通过隐含参数_optimizer_batch_table_access_by_rowid可以改变执行计划. SYS@test> @ hide _optimizer_batch_table_access_by_rowid NAME DESCRIPTION DEFAULT_VALUE SESSION_VALUE SYSTEM_VALUE ...