overview Oracle's cost-based optimizer (COB) uses statistics to calculate the selectivity (the fraction of rows in a table that the SQL statement's predicate chooses) of predicates and to estimate the "cost" of each execution plan. The COB will
照着书敲的.留作笔记吧. using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Runtime.InteropServices; namespace _18获取本机磁盘信息 { class Program { static void Main(string[] args) { GetDiskInfo(); Console.ReadKey(); } [Dl
Oracle重建所有表的索引的sql: SELECT 'alter index ' || INDEX_NAME || ' rebuild online nologging;' FROM USER_INDEXES WHERE TABLESPACE_NAME = 'xxx' AND STATUS = 'VALID' AND TEMPORARY = 'N' AND INDEX_TYPE = 'NORMAL' AND PARTITIONED = 'NO'; 然后把结果放到PLSQL命令容器执行即可. O
CREATE OR REPLACE PROCEDURE SchameB.PRC_GATHER_STATS AUTHID CURRENT_USER IS BEGIN SYS.DBMS_STATS.GATHER_TABLE_STATS('SchName', 'TableName', CASCADE => TRUE); END; / select owner,table_name,last_analyzed,num_rows from dba_tables where owner='SYSTEM' a
在11g中,默认自己主动收集统计信息的时间为晚上10点(周一到周五,4个小时),早上6点(周六,周日,20个小时),例如以下所看到的: select a.window_name, a.repeat_interval,a.duration from dba_scheduler_windows a, dba_scheduler_wingroup_members b where a.window_name = b.window_name and b.window_group_name = 'MAINT
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' >>文件: 磁盘信息.py >>作者: liu yang >>邮箱: liuyang0001@outlook.com ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''