NOTES on concepts ---schema objects
1. Object types
1) table: store data in row
2) index
3) partition: pieces of large tables and indexes
4) view
5) sequence
6) dimension:A dimension defines a parent-child relationship between pairs of column sets which must come from the same table.
7) synonym
8) PL/SQL subprograms and packages
9) users, roles, contexts, and directory objects
2. Object Storage
Some schema objects store data in logical storage structures called segments.
Other
schema objects, such as views and sequences, consist of metadata only.
3. SYS and SYSTEM schema
SYS account
- automatically created when a database is created
- can perform. all database administrative functions
- store the base tables and views for the data dictionary
- Tables in the SYS schema are manipulated only by the database and must never be modified by any user
- automatically created when a database is created
- store additional tables and views that display administrative information, and internal tables and views used by various Oracle Database options and tools
- Never use the SYSTEM schema to store tables of interest to nonadministrative users.
datafile_tablespace_segment.JPG来自 “ ITPUB博客 ” ，链接：https://blog.itpub.net/26679417/viewspace-750246/ ，如需转载，请注明出处，否则将追究法律责任。
请登录后发表评论
登录
全部评论
