Introduction to SQL Tuning

1. Introduction to SQL Tuning
1. :
1. SQL ;
2. SQL ;
3. ;
2. SQL :
1. Stale or missing optimizer statistics: ;
2. Missing access structures: , ;
3. Suboptimal execution plan selection: ;
4. Poorly constructed SQL:SQL ;
5. , . ;
6. :
1. , ;
2. , ;
3. , oracle ;
4. UNION ALL UNION;
5. , , hash , CPU ;
3. ;
4. Oracle ;
5. :
1. Automatic Database Diagnostic Monitor (ADDM);
2. SQL Tuning Advisor;
3. SQL Tuning Sets;
4. SQL Access Advisor;
5. SQL Performance Analyzer;
6. SQL Monitoring;
7. SQL Plan Management: 11g , sql ;
6. SQL :
1. SQL ;
2. ;
3. ;
4. ;
5. ;
6. ;
7. CPU Wait Time
1. db_time=cpu_time+wait_time;
2. db_time ,cpu_time wait_time , , ;
3. db_time ,cpu_time wait_time , SQL , SQL ;
4. db_time ,cpu_time wait_time , IO ;
8. :
1. Bad connection management: ;
2. Bad use of cursors and the shared pool: SGA PGA, ;
3. Excess of resources consuming SQL statements:sql ;
4. Use of nonstandard initialization parameters: ;
5. Poor database disk configuration:IO ;
6. Redo log setup problems: , , 20 ;
7. Excessive serialization: , , , ;
8. Inappropriate full table scans: , ;
9. Large number of space-management or parse-related generated SQL statements:
SQL;
10. Deployment and migration errors: , ;
9. :
1. ;
2. :
1. ;
2. Oracle Designer, ;
3. OLTP DW ;
3. :
1. , , , ;
2. where , ;
3. ;, check, DML;
4. , ;
4. :
1. WHERE ;
2. DW , OLTP , ;
5. :
1. , ;
2. ;
10. Share Cursors
1. ;
2. cursor_sharing ;