一、Oracle系统视图归纳总结
Oracle 19C有2067个系统视图，但只有部分常用视图在运维或查问题中会使用到，我们可以将注意力放在常用系统视图上。(实际上我们在接触任何数据库时，都需要学习常用系统视图)
Oracle系统视图主要分为4类：
1. DBA_* 表示DBA拥有的或可访问的所有对象
2. ALL_* 表示某用户拥有的或可访问的所有对象
3. USER_* 表示某用户拥有的所有对象
4. V$* 动态性能视图
1.1 常用系统视图
| 序号 | 视图 |
|---|---|
| 1 | *_TAB_COLUMNS |
| 2 | *_TAB_COLS |
| 3 | *_TAB_PARTITIONS |
| 4 | *_PART_TABLES |
| 5 | *_TAB_SUBPARYITIONS |
| 6 | *_TABLES |
| 7 | *_INDEXS |
| 8 | *_IND_PARTITIONS |
| 9 | *_IND_EXPRESSIONS |
| 10 | *_IND_COLUMNS |
| 11 | *_SOURCE |
| 12 | *_CONSTRAINTS |
| 13 | *_CONS_COLUMNS |
| 14 | *_COL_COMMENTS |
| 15 | *_TAB_COMMENTS |
| 16 | *_OBJECTS |
| 17 | *_DIRECTORIES |
| 18 | *_TABLESPACES |
| 19 | *_SCHEDULER_JOBS |
| 20 | *_PROCEDURES |
| 21 | *_SEQUENCES |
| 22 | *_JOBS |
| 23 | *_TYPE_ATTRS |
| 24 | *_USERS |
| 25 | *_TRIGGERS |
| 26 | *_IND_SUBPARTITIONS |
| 27 | *_SYNONYMS |
| 28 | *_ARGUMENTS |
| 29 | *_PART_INDEXS |
| 30 | *_VIEWS |
| 31 | *_LOBS |
| 32 | *_SEGMENTS |
| 33 | V$INSTANCE/GV$INSTANCE |
| 34 | V$SESSION |
| 35 | V$DATABASE |
| 36 | V$MYSTAT |
二、常用查询语句
2.1 查询表、表字段、视图、序列、存储过程、索引等数据库对象信息
select table_name from user_tables;
select * from user_sequences;
select * from user_synonyms;
select * from user_triggers;
select * from user_source;
查询数据库对象
select * from user_objects;
select object_name,procedure_name,object_type from user_procedures where object_type= 'PACKAGE' order by 1,2;
select object_name,procedure_name,object_type from user_procedures where object_type= 'PROCEDURE' order by 1,2;
select object_name,procedure_name,object_type from user_procedures where object_type= 'FUNCTION' order by 1,2;
select view_name from user_views;
查询索引信息
select table_owner,table_name,index_name,uniqueness,partitined,status from user_index where index_type <> 'LOB' order by table_name;
查询表字段信息
select table_name,column_name,data_type from user_tab_cols order by table_name,column_id;
查询视图字段信息
select table_name,column_name,data_type,data_length from user_tab_columns order by table_name,column_id;
查询分区表
select table_name,partition_name,high_value from user_tab_partitions order by table_name;
2.2 查询会话、动态性能视图
查询当前实例状态
select INSTANCE_NUMBER,INSTANCE_NAME,HOST_NAME,VERSION,STARTUP_TIME.STATUS FROM v$instance;
查询当前每个会话的会话信息
select $ADDR,SID,SERIAL#,AUDSID,USERNAME,OSUSER,MACHINE,PROHRAM,PREV_SQL_ADDR,PREV_HASH_VALUE from v$session where user='XXX';
查询当前会话的统计信息
select sid from V$MYSTAT where ROWNUM=1;