enq: SQ - contention

--每分钟执行情况

SQL> select  sql_id, mi, count(mi)

2    from (select event, sql_id, to_char(sample_time, ‘yyyymmdd hh24mi‘) mi --,

3          --session_id

4            from dba_hist_active_sess_history

5           where sql_id = ‘7wxfw53bsmgpq‘

6             and sample_time > to_date(‘20140717 0940‘, ‘yyyymmdd hh24mi‘)

7             and sample_time < to_date(‘20140717 0950‘, ‘yyyymmdd hh24mi‘))

8   group by  sql_id, mi

9    order by mi ;

SQL_ID        MI             COUNT(MI)

------------- ------------- ----------

7wxfw53bsmgpq 20140717 0942          1

7wxfw53bsmgpq 20140717 0943         23

7wxfw53bsmgpq 20140717 0944        125

7wxfw53bsmgpq 20140717 0946         96

7wxfw53bsmgpq 20140717 0947        114

7wxfw53bsmgpq 20140717 0949         44

通过图片，发现对 第一条获取序列的语句比较暂用性能

--等待事件以及语句情况

SQL> select  event,sql_id, mi, count(mi)

2    from (select substrb(event,1.30) event, sql_id, to_char(sample_time, ‘yyyymmdd hh24mi‘) mi --,

3          --session_id

4            from dba_hist_active_sess_history

5           where sql_id = ‘7wxfw53bsmgpq‘

6             and sample_time > to_date(‘20140717 0940‘, ‘yyyymmdd hh24mi‘)

7             and sample_time < to_date(‘20140717 0950‘, ‘yyyymmdd hh24mi‘))

8   group by  event,sql_id, mi

9    order by mi ;

EVENT                                                            SQL_ID        MI             COUNT(MI)

---------------------------------------------------------------- ------------- ------------- ----------

7wxfw53bsmgpq 20140717 0942          1

buffer busy waits                                                7wxfw53bsmgpq 20140717 0943          1

enq: SQ - contention                                             7wxfw53bsmgpq 20140717 0943         22

buffer busy waits                                                7wxfw53bsmgpq 20140717 0944          3

enq: SQ - contention                                             7wxfw53bsmgpq 20140717 0944        122

buffer busy waits                                                7wxfw53bsmgpq 20140717 0946          2

enq: SQ - contention                                             7wxfw53bsmgpq 20140717 0946         94

buffer busy waits                                                7wxfw53bsmgpq 20140717 0947          2

enq: SQ - contention                                             7wxfw53bsmgpq 20140717 0947        112

buffer busy waits                                                7wxfw53bsmgpq 20140717 0949          1

enq: SQ - contention                                             7wxfw53bsmgpq 20140717 0949         43

--大小获取查询

SQL> select sequence_name,cache_size from dba_sequences where sequence_name like upper(‘%qreque%‘);

SEQUENCE_NAME                  CACHE_SIZE

------------------------------ ----------

QREQUESTNO                             20 改成100  在测试

SQL>

--大小获取查询

SQL> select sequence_name,cache_size from dba_sequences where sequence_name like upper(‘%qreque%‘);

SEQUENCE_NAME                  CACHE_SIZE

------------------------------ ----------

QREQUESTNO                             20 改成100  在测试

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