[bbk2341] 第46集 - Chapter 09-Optimizing Sore Perations(01)

When to Gather Statistics

在10g、11g里面，搜集statistics信息分自动和手工方式两种.

Table Statistics

  • Number of rows
  • Number of blocks and empty blocks
  • Average available free space
  • Number of chained or migrated rows
  • Average row length
  • Last analyze date and smaple size
  • Data dictionary view:dba_tables

查看表的统计信息，主要依据数据字典dba_tables

Index Statistics

  • Index level(height)
  • Number of leaf blocks and distinct keys
  • Average number of leaf blocks per key
  • Average number of data blocks per key
  • Number of index entries
  • Clustering factor:反应了表的排序程度.
  • Data dictionary view:dba_indexes

Index Tuning Wizard

 

posted @ 2013-05-07 13:27  ArcerZhang  阅读(121)  评论(0)  编辑  收藏  举报