V$INSTANCE

V$INSTANCE displays the state of the current instance.

Column	Datatype	Description
INSTANCE_NUMBER	NUMBER	Instance number used for instance registration (corresponds to the INSTANCE_NUMBER initialization parameter)
INSTANCE_NAME	VARCHAR2(16)	Name of the instance
HOST_NAME	VARCHAR2(64)	Name of the host machine
VERSION	VARCHAR2(17)	Database version
STARTUP_TIME	DATE	Time when the instance was started
STATUS	VARCHAR2(12)	Status of the instance: ·         STARTED - After STARTUP NOMOUNT ·         MOUNTED - After STARTUP MOUNT or ALTER DATABASE CLOSE ·         OPEN - After STARTUP or ALTER DATABASE OPEN ·         OPEN MIGRATE - After ALTER DATABASE OPEN { UPGRADE | DOWNGRADE }
PARALLEL	VARCHAR2(3)	Indicates whether the instance is mounted in cluster database mode (YES) or not (NO)
THREAD#	NUMBER	Redo thread opened by the instance
ARCHIVER	VARCHAR2(7)	Automatic archiving status: ·         STOPPED ·         STARTED ·         FAILED - Archiver failed to archive a log last time but will try again within 5 minutes
LOG_SWITCH_WAIT	VARCHAR2(15)	Event that log switching is waiting for: ·         ARCHIVE LOG ·         CLEAR LOG ·         CHECKPOINT ·         NULL - ALTER SYSTEM SWITCH LOGFILE is hung but there is room in the current online redo log
LOGINS	VARCHAR2(10)	Indicates whether the instance is in unrestricted mode, allowing logins by all users (ALLOWED, or in restricted mode, allowing logins by database administrators only (RESTRICTED)
SHUTDOWN_PENDING	VARCHAR2(3)	Indicates whether a shutdown is pending (YES) or not (NO)
DATABASE_STATUS	VARCHAR2(17)	Status of the database: ·         ACTIVE ·         SUSPENDED ·         INSTANCE RECOVERY
INSTANCE_ROLE	VARCHAR2(18)	Indicates whether the instance is an active instance (PRIMARY_INSTANCE) or an inactive secondary instance (SECONDARY_INSTANCE), or UNKNOWN if the instance has been started but not mounted
ACTIVE_STATE	VARCHAR2(9)	Quiesce state of the instance: ·         NORMAL - Database is in a normal state. ·         QUIESCING - ALTER SYSTEM QUIESCE RESTRICTED has been issued: no new user transactions, queries, or PL/SQL statements are processed in this instance. User transactions, queries, or PL/SQL statements issued before the ALTER SYSTEM QUIESCE RESTRICTED statement are unaffected. DBA transactions, queries, or PL/SQL statements are also unaffected. ·         QUIESCED - ALTER SYSTEM QUIESCE RESTRICTED has been issued: no user transactions, queries, or PL/SQL statements are processed. DBA transactions, queries, or PL/SQL statements are unaffected. User transactions, queries, or PL/ SQL statements issued after the ALTER SYSTEM QUIESCE RESTRICTED statement are not processed. A single ALTER SYSTEM QUIESCE RESTRICTED statement quiesces all instances in an Oracle RAC environment. After this statement has been issued, some instances may enter into a quiesced state before other instances; the system is quiesced when all instances enter the quiesced state.
BLOCKED	VARCHAR2(3)	Indicates whether all services are blocked (YES) or not (NO)

Note:

1. Querying ACTIVE_STATE column of V$INSTANCE view reveals the current state of an instance. Its values are:

·         NORMAL: normal unquiesced state.

·         QUIESCING: being quiesced, but some non-DBA sessions (username not as SYSTEM or SYS) are still active.

·         QUIESCED: Quiesced; no non-DBA sessions are active or allowed.

2. After issuing ALTER SYSTEM SUSPEND / RESUME statement, query DATABASE_STATUS confirms the database status: SUSPENDED / ACTIVE.
3. Script using V$INSTANCE

-- to find the uptime of an instance SELECT (SYSDATE - STARTUP_TIME) FROM V$INSTANCE;

-- to show PGA statistics for each session and background process SELECT   to_char(ssn.sid, '9999') || ' - ' || nvl(ssn.username, nvl(bgp.name, 'background'))          || nvl(lower(ssn.machine), ins.host_name) "SESSION",          to_char(prc.spid, '999999999') "PID/THREAD",          to_char((se1.value/1024)/1024, '999G999G990D00') || ' MB' "      CURRENT SIZE",          to_char((se2.value/1024)/1024, '999G999G990D00') || ' MB' "      MAXIMUM SIZE"  FROM     v$sesstat se1, v$sesstat se2, v$session ssn, v$bgprocess bgp, v$process prc,           v$instance ins,  v$statname stat1, v$statname stat2  WHERE    se1.statistic# = stat1.statistic# and stat1.name = 'session pga memory'  AND      se2.statistic#  = stat2.statistic# and stat2.name = 'session pga memory max'  AND      se1.sid        = ssn.sid  AND      se2.sid        = ssn.sid  AND      ssn.paddr      = bgp.paddr (+)  AND      ssn.paddr      = prc.addr  (+)

-- to show database license usage SELECT rpad(c.name||':',11) || rpad(' current logons=' ||        (to_number(b.sessions_current)),20) || 'cumulative logons=' ||        rpad(substr(a.value,1,10),10) || 'highwater mark=' || b.sessions_highwater ||        '   startup time=' || to_char(d.startup_time,'YYYY/MM/DD HH24:MI:SS') Information FROM   V$SYSSTAT a, V$LICENSE b, V$DATABASE c, V$INSTANCE d WHERE  a.name = 'logons cumulative';

-- to check if a database is in restricted mode SQL> select logins from v$instance; LOGINS ---------- RESTRICTED

-- to check the database version select version from v$instance;

-- check that the instance status is good for upgrading select instance_name, status, logins, ACTIVE_STATE, DATABASE_STATUS from V$instance; INSTANCE_NAME    STATUS       LOGINS     ACTIVE_ST DATABASE_STATUS ---------------- ------------ ---------- --------- ----------------- Mydb             OPEN MIGRATE RESTRICTED NORMAL    ACTIVE

-- query startup time select to_char(startup_time, 'HH24:MI DD-MON-YY') "Startup time" from   v$instance;

-- calculate instance uptime select 'Hostname : ' || host_name        , 'Instance Name : ' || instance_name        , 'Started At : ' || to_char(startup_time,'DD-MON-YYYY HH24:MI:SS') stime        , 'Uptime : ' || floor(sysdate - startup_time) || ' days(s) ' ||        trunc( 24*((sysdate-startup_time) -        trunc(sysdate-startup_time))) || ' hour(s) ' ||           mod(trunc(1440*((sysdate-startup_time) -           trunc(sysdate-startup_time))), 60) ||' minute(s) ' ||           mod(trunc(86400*((sysdate-startup_time) -           trunc(sysdate-startup_time))), 60) ||' seconds' uptime from   v$instance;

Oracle data dictionary views

Oracle dynamic performance views

Last updated: October 6 2009 Tuesday