解释输出和分布统计信息收集.docVIP

解释输出与分布统计信息收集 1. 首先我们运行如下的解释语句 D:\Program Files\IBM\SQLLIB\BINdb2expln -d sample -q select * from employee where empno=000010 -t -g -i 或者是： D:\Program Files\IBM\SQLLIB\BINdynexpln -d sample -q select * from employee where empno=000010 -t -g -i DB2 Universal Database Version 9.5, 5622-044 (c) Copyright IBM Corp. 1991, 2007 Licensed Material - Program Property of IBM IBM DB2 Universal Database SQL and XQUERY Explain Tool DB2 Universal Database Version 9.5, 5622-044 (c) Copyright IBM Corp. 1991, 2007 Licensed Material - Program Property of IBM IBM DB2 Universal Database SQL and XQUERY Explain Tool ******************** DYNAMIC *************************************** ==================== STATEMENT ========================================== Isolation Level = Cursor Stability Blocking = Block Unambiguous Cursors Query Optimization Class = 5 Partition Parallel = No Intra-Partition Parallel = No SQL Path = SYSIBM, SYSFUN, SYSPROC, SYSIBMADM, ZHANGRAN Statement: select * from employee where empno=000010 Section Code Page = 1208 Estimated Cost = 7.579099 Estimated Cardinality = 1.000000 ( 2) Access Table Name = ZHANGRAN.EMPLOYEE ID = 2,6 | Index Scan: Name = ZHANGRAN.PK_EMPLOYEE ID = 1 | | Regular Index (Not Clustered) | | Index Columns: | | | 1: EMPNO (Ascending) | #Columns = 13 | Single Record | Fully Qualified Unique Key | Avoid Locking Committed Data | #Key Columns = 1 | | Start Key: Inclusive Value | | | | 1: 000010 | | Stop Key: Inclusive Value | | | | 1: 000010 | Data Prefetch: Eligible 0 | Index Prefetch: None | Lock Intents | | Table: Intent Share | | Row : Next Key Share | Sargable Predicate(s) ( 2) | | Return Data to Application |