统计等待事件：

BLOCKING_SESSION   COUNT(*)
---------------- ----------
             243          1
            9695          1
            8368          1
            1323          1
            1345         91
            9257       3626
             221          1
            4417          2
            4185          1
            8815          4
            1128          2

查询9257阻塞：

SESSION_ID SAMPLE_TIME
---------- ----------------------------------------
EVENT                          SQL_ID        BLOCKING_SESSION
------------------------------ ------------- ----------------
      9257 27-JUN-20 02.00.44.546 PM
gc current block 2-way         xxxxx

      9257 27-JUN-20 02.00.54.586 PM
row cache lock                 xxxxxx             1345

      9257 27-JUN-20 02.01.04.626 PM
row cache lock                 xxxxxx             1345


SESSION_ID SAMPLE_TIME
---------- ----------------------------------------
EVENT                          SQL_ID        BLOCKING_SESSION
------------------------------ ------------- ----------------
      9257 27-JUN-20 02.01.14.817 PM
row cache lock                 xxxxxx             1345

      9257 27-JUN-20 02.01.24.867 PM
row cache lock                 xxxxx             1345

      9257 27-JUN-20 02.01.34.907 PM
row cache lock                 xxxxxx             1345


SESSION_ID SAMPLE_TIME
---------- ----------------------------------------
EVENT                          SQL_ID        BLOCKING_SESSION
------------------------------ ------------- ----------------
      9257 27-JUN-20 02.01.44.957 PM
row cache lock                 xxxxxx             1345

      9257 27-JUN-20 02.01.55.007 PM
row cache lock                 xxxxxxx             1345

      9257 27-JUN-20 02.02.05.047 PM
row cache lock                 xxxxx             1345

查询1345阻塞：

SESSION_ID SAMPLE_TIME
---------- ----------------------------------------
EVENT                          SQL_ID        BLOCKING_SESSION
------------------------------ ------------- ----------------
      1345 27-JUN-20 02.00.34.496 PM
                               xxxxxx

      1345 27-JUN-20 02.00.54.586 PM
library cache lock             xxxxxx             9257

      1345 27-JUN-20 02.01.04.626 PM
library cache lock             xxxxx             9257

9257执行sql：call dbms_stats.gather_database_stats_job_proc ( )

1345执行sql：alter index “name”.“biao” modify partition “PPP” shrink space CHECK

我想查询一下alter index这个sql是由谁执行的。是收集统计信息的时候自动执行，还是其他？如何操作？