TRACE 분석 관련 질문 - STATSPACK 레벨 확인 등

Question

TRACE 분석을 해보면 실행계획은 빠져나와서 DBA분에게 LEVEL 6로 요청을 할 예정입니다.
1.
그런데.. 현재 STATSPACK LEVEL 을 직접 확인할 방법이 없나 궁금하네요
2.
Row Source Operation 부분을 보면
TABLE ACCESS FULL ....... (cr=7425 pr=0 pw=0 time=3638239 us)
이렇게 되어있는데
CR, PR, PW, TIME, US 의 의미, 단위가 궁금합니다.
글보시는 분들 모두 연휴 잘 보내세요~

Answer 1

1. 아래처럼 statspack report를 보면 나오지요.
Snap Snap
Instance DB Name Id Snap Started Level Comment
2 18 Dec 2006 15:33 5
3 22 Dec 2006 17:27 10
4 22 Dec 2006 18:00 10
5 22 Dec 2006 19:00 10
6 22 Dec 2006 20:00 10
perfstat우저에서 $ORACLE_HOME/rdbms/admin/spreport.sql 을 수행하면
Level부분이 있습니다. 이 부분을 보면 되겠구요.
아래 쿼리로도 확인할 수 있습니다.
select snap_id, to_char(startup_time, 'YYYY-MON-DD:HH24:MI:SS') insert_fmt,
     to_char(snap_time, 'YYYY-MON-DD:HH24:MI:SS') snapdat,
          snap_level "level"
from stats$snapshot
order by snap_id;
SNAP_ID INSERT_FMT SNAPDAT level
52 2006-DEC-23:02:31:48 2006-DEC-23:08:44:10 5
62 2006-DEC-23:02:31:26 2006-DEC-23:08:44:31 5
그리고 statspack level에서 level 6으로 설정하는 방법은..
아래를 crontab에 sqlplus로 들어가서 수행하는 쉘로 등록해두면 되겠죠.
execute statspack.snap(I_SNAP_LEVEL=>6);
참고로 statspack level별로 수집할 수 있는 정보는 아래와
같습니다.
Levels = 0 General performance statistics
Statistics gathered:
This level and any level greater than 0 collects general
performance statistics, such as: wait statistics, system events,
system statistics, rollback segment data, row cache, SGA,
background events, session events, lock statistics,
buffer pool statistics, parent latch statistics.
Levels = 5 Additional data: SQL Statements
This level includes all statistics gathered in the lower level(s),
and additionally gathers the performance data on high resource
usage SQL statements.
SQL 'Thresholds'
The SQL statements gathered by Statspack are those which exceed one of
four predefined threshold parameters:
- number of executions of the SQL statement (default 100)
- number of disk reads performed by the SQL statement (default 1,000)
- number of parse calls performed by the SQL statement (default 1,000)
- number of buffer gets performed by the SQL statement (default 10,000)
The values of each of these threshold parameters are used when
deciding which SQL statements to collect - if a SQL statement's
resource usage exceeds any one of the above threshold values, it
is captured during the snapshot.
The SQL threshold levels used are either those stored in the table
stats$statspack_parameter, or by the thresholds specified when
the snapshot is taken.
Levels = 6
This level includes all statistics gathered in the lower level(s).
Additionally, it gathers SQL plans and plan usage data for each of the
high resource usage SQL statements captured. Therefore, level 6 snapshots
should be used whenever there is the possibility that a plan may change.
To gather the plan for a SQL statement, the statement must be in the shared
pool at the time the snapshot is taken, and it must exceed one of the SQL
thresholds. To gather plans for all statements in the shared pool, specify
the executions threshold to be zero (0) for those snapshots.
Levels = 10 Additional statistics: Child latches
This level includes all statistics gathered in the lower levels, and
additionally gathers high Child Latch information. Data gathered at
this level can sometimes cause the snapshot to take longer to complete
i.e. this level can be resource intensive, and should only be used
when advised by Oracle personnel.
2. Resource Source Operation 에서의 단위는 아래와 같습니다.
cr= : Consistent Read 총블록수
r= (Oracle Database 10g는 pr=) : Physical Read 총블록수
w= (Oracle Database 10g는 pw=): Physical Write 총블록수
time= : 전체 처리시간(마이크로초(1/1000000초) 단위)
그리고 cs us ms는 time의 단위를 말합니다.
-> s - second
-> cs - centisecond - 100th of a second
-> ms - millisecond - 1000th of a second
-> us - microsecond - 1000000th of a second