Interpreting Execution Plans

1. Interpreting Execution Plans
1. :
1. ;
2. ;
3. ;
2. :
1. SQL ;
2. , ;
3. :
1. PLAN_TABLE: EXPLAIN PLAN SQL/PLUS autotrace , ;
2. v$sql_plan: Shared Pool Library Cache ;
3. v$sql_plan_monitor:11g ;
4. dba_hist_sql_plan: AWR ;
5. stats$sql_plan: Statspack ;
6. SQL Management Base: SQL Plan Management Baselines ;
7. SQL tuning set;
8. DBMS_MONITOR trace : 10046 ;
9. 10053 trace ;
10. 10gR2 dump ;
4. :
1. , , SQL , DBMS_XPLAN
;
2. DBMS_XPLAN.DISPLAY(): plan_table ;
3. DBMS_XPLAN.DISPLAY_CURSOR(): v$sql_plan ;
4. DBMS_XPLAN.DISPLAY_AWR(): AWR ;
5. DBMS_XPLAN.DISPLAY_SQLSET(): SQL tuning set ;
6. DBMS_XPLAN.DISPLAY_SQL_PLAN_BASELINE(): SQL Plan Management Baselines
;
5. EXPLAIN TABLE :
1. , PLAN_TABLE , SQL ;
2. :EXPLAIN PLAN [SET STATEMENT_ID = 'text'] [INTO plan_table] FOR statement;
PLAN_TABLE ;
3. PLAN_TABLE:
1. EXPLAN_PLAN PLAN_TABLE, , sys.plan_table$
;SELECT * FROM dba_synonyms WHERE synonym_name = 'PLAN_TABLE';SELECT
table_name, TEMPORARY, duration FROM dba_tables WHERE table_name =
'PLAN_TABLE$';
2. $ORACLE_HOME/rdbms/admin/utlxplan.sql , ,
session , ;
3. SQL ; , ,
;
4. , ID PAREANT_ID ;
4. DBMS_XPLAN.DISPLAY :DBMS_XPLAN.DISPLAY(table_name, statement_id, format,
filter_preds):
1. table_name: PLAN_TABLE ;
2. statement_id: , ;
3. format: TYPICAL , , ;
4. ;
5. statement_id ;
6. ;
6. AUTOTRACE:
1. AUTOTRACE sql*plus , oracle7.3 , PLAN_TABLE ;
2. PLUSTRACE v$ , $ORACLE_HOME/sqlplus/admin/plustrce.sql
;
3. , ;
4. EXPLAIN PLAN , ;
5. :SET AUTOT[RACE] {OFF | ON | TRACE[ONLY]} [EXP[LAIN]] [STAT[ISTICS]];
1. ON: trace ;
2. TRACEONLY: ;
6. :show autotrace;
7. :
1. recursive calls: , , , . , ;
, , ; shared_pool :alter system flush
shared_pool;
2. db block gets: block . DML db block gets ,
,SELECT , REDO CR ;
3. consistent gets: ( BLOCK), , arraysize ;
1. arraysize: , show arraysize ;
2. :consistent gets=rows processed/arraysize, ;
3. arraysize , ;
4. physical reads: , BLOCK ,BUFFER CACHE , BUFFER
CACHE :alter system flush buffer_cache;
5. redo size: , DML ;
6. bytes sent via SQL*Net to client: ;
7. bytes received via SQL*Net from client: ;
8. SQL*Net roundtrips to/from client:SQL , arraysize ;
9. sorts (memory): , PGA;
10. sorts (disk): , ;
11. rows processed: ;
8. v$sql_plan:
1. v$sql_plan: library cahce ;PLAN_TABLE ;
2. sql_id v$sql , address hash_value ;
3. :
1. HASH_VALUE: library cache ;
2. ADDRESS: SQL , ;
3. CHILD_NUMBER: CURSOR ;
4. POSITION: PARENT_ID ;
5. PARENT_ID: ID, , , ;
6. ID: ;
7. PLAN_HASH_VALUE: ;
4. :SELECT * FROM table(DBMS_XPLAN.DISPLAY_CURSOR('sql_id'));
5. v$sql_plan_statistics:
1. STATISTICS_LEVEL ALL ;
2. GATHER_PLAN_STATISTICS hint;
3. v$sql_plan_statistics_all: ;
6. v$sql_workarea: SQL CURSOR ;
9. AWR:
1. AWR , , ;
2. :
1. ;
2. ;
3. session ;
4. ASH(Active Session History) ;
3. ;
4. AWR :
1. V$ACTIVE_SESSION_HISTORY;
2. V$metric views;
3. DBA_HIST views:
1. DBA_HIST_ACTIVE_SESS_HISTORY;
2. DBA_HIST_BASELINE;
3. DBA_HIST_DATABASE_INSTANCE;
4. DBA_HIST_SNAPSHOT;
5. DBA_HIST_SQL_PLAN;
6. DBA_HIST_WR_CONTROL;
5. sql_id AWR sql : SELECT plan_table_output FROM
TABLE(DBMS_XPLAN.DISPLAY_AWR('g22czkqq3pxmb'));
6. AWR SQL :@$ORACLE_HOME/rdbms/admin/awrsqrpt;
10. SQL Monitoring:11g;
11. :
1. :
1. , ;
2. ;
3. ;
2. :
1. : , , , ;
2. : , , , ;
3. : , , , ;
3. :
1. :356421;
2. :43652871;
3. :325410;
4. :
1. , ;
2. ;
3. , , ;
4. ;
12. , SQL Tuning Advisor ;