Oracle alarm logs, dynamic performance views, and data dictionaries

1. Check the alarm log

/u01/app/oracle/diag/rdbms/orcl/orcl/trace/alert_orcl.log

Real-time logs: Tail-f/u01/app/oracle/diag/rdbms/orcl/orcl/trace/alert_orcl.log

Trace File ADR

2. Dynamic performance view (v$) saved in memory

Information used to access the changing state of the instance memory structure (control file + instance)

Session data

Wait events

Memory Allocations

Running SQL

Undo Usage

Open cursors

Redo Log Usage

....

Different moments can be viewed differently in the dynamic performance view:

Startup Nomount Stage:

Select status from V$instance;

Select Paddr,port from V$session;

Startup Mount Stage:

Select Open_mode from V$database;

Select name from V$datafile;

Select member from V$logfile;

Select addr from V$lock;

Select Paddr,port from V$session;

SELECT * from V$SGA;

Select COUNT (*) from V$sql;

Startup phase:

SELECT * from V$PGA;

Select COUNT (*) from v$fixed_table where name like ' v$% ';//view how many tables the dynamic performance view has

3. Data dictionary exists in table

Table indexes views users schemals procedures ...

Dba_: Access to all objects

All_: All objects that the user has permission to view

User_: User-owned objects

Select COUNT (*) from Dba_tables;

Select COUNT (*) from All_tables;

Example:::

Alter user Scott account unlock identified by Tiger;

Sql> Conn Scott/tiger;

Connected.

Sql> select * from tab;

Tname tabtypeClusterid

------------------------------ ------- ----------

BONUS TABLE

DEPT TABLE

EMP TABLE

Salgrade TABLE

See what tables Scott users can see, how many tables are in total

Sql> Select COUNT (*) from All_tables;

COUNT (*)

----------

103

Sql> Select COUNT (*) from User_tables;

COUNT (*)

----------

4

See which tables Scott users have:

Sql> Select table_name from User_tables;

table_name

------------------------------

DEPT

Emp

BONUS

Salgrade

########

View All Users

Select Username,account_status from Dba_users;

See what data dictionary tables are available

Select table_name from dictionary;

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Oracle alarm logs, dynamic performance views, and data dictionaries