Resizing Undo Tablespaces
Author
Ural Ural
Oracle DBA
How do you resize undo tablepaces ? This is how I do it in an Oracle 9i database.
Problem is the undo tablespace has grown up to the limit of its maxsize
and we need to compact it or just we want to make it smaller due to a space problem
--Find undo info
SELECT NAME, VALUE
FROM v$parameter
WHERE LOWER (NAME) LIKE '%undo%';
NAME|VALUE
undo_management|AUTO
undo_tablespace|UNDOTBS1
--Find undo tablespace datafile info
SELECT file_name, BYTES / 1024 / 1024 mb
FROM dba_data_files
WHERE tablespace_name = 'UNDOTBS1'
ORDER BY file_name;
/*
FILE_NAME|MB
/datac3/oradata/andlp2/undotbs1_01.dbf|1793
/datac6/oradata/andlp2/undotbs1_02.dbf|235
/datac7/oradata/andlp2/undotbs1_03.dbf|1679
*/
--Execute the following query to determine who is using a particular UNDO or Rollback Segment:
SELECT TO_CHAR (s.SID) || ',' || TO_CHAR (s.serial#) sid_serial,
NVL (s.username, 'None') orauser, s.program, r.NAME undoseg,
t.used_ublk * TO_NUMBER (x.VALUE) / 1024 || 'K' "Undo"
FROM SYS.v_$rollname r,
SYS.v_$session s,
SYS.v_$transaction t,
SYS.v_$parameter x
WHERE s.taddr = t.addr
AND r.usn = t.xidusn(+)
AND x.NAME = 'db_block_size'
--No rows returned
--Create a second temporary undo tablespace
CREATE UNDO TABLESPACE UNDOTBS2 DATAFILE
'/datac7/oradata/andlp2/undotbs2_01.dbf' SIZE 500M AUTOEXTEND ON NEXT 16M MAXSIZE 5000M
ONLINE
BLOCKSIZE 8K;
--Set this new undo tablespace as undo tablespace of the database
ALTER SYSTEM SET undo_tablespace = UNDOTBS2;
--You can monitor the undo extents of all the undo tablespaces by using the following query
SELECT tablespace_name, segment_name, SUM (blocks), SUM (BYTES) / 1024
FROM dba_undo_extents
GROUP BY tablespace_name, segment_name;
--Since we are going to drop the old undo tablespace we need to know if any session is
--using any undo extent of this undo tablespace
SELECT TO_CHAR (s.SID) || ',' || TO_CHAR (s.serial#) sid_serial,
NVL (s.username, 'None') orauser, s.program, r.NAME undoseg,
t.used_ublk * TO_NUMBER (x.VALUE) / 1024 || 'K' "Undo",
t1.tablespace_name
FROM SYS.v_$rollname r,
SYS.v_$session s,
SYS.v_$transaction t,
SYS.v_$parameter x,
dba_rollback_segs t1
WHERE s.taddr = t.addr
AND r.usn = t.xidusn(+)
AND x.NAME = 'db_block_size'
AND t1.segment_id = r.usn
AND t1.tablespace_name = 'UNDOTBS1'
/*
SID_SERIAL|ORAUSER|PROGRAM|UNDOSEG|Undo|TABLESPACE_NAME
615,998|USER1|runform30x@host1 (TNS interface)|_SYSSMU102$|8K|UNDOTBS1
*/
--You can get more info about the undo extent that is online (used)
SELECT *
FROM dba_rollback_segs
WHERE status = 'ONLINE'
AND tablespace_name = 'UNDOTBS1'
ORDER BY tablespace_name, segment_name
/*
SEGMENT_NAME|OWNER|TABLESPACE_NAME|SEGMENT_ID|FILE_ID|BLOCK_ID|INITIAL_EXTENT|NEXT_EXTENT|MIN_EXTENTS|MAX_EXTENTS|PCT_INCREASE|STATUS|INSTANCE_NUM|RELATIVE_FNO
_SYSSMU102$|PUBLIC|UNDOTBS1|102|33|4473|131072||2|32765||ONLINE||33
*/
--Monitor the status of online undo extents
SELECT segment_name, xacts, v.status
FROM v$rollstat v, dba_rollback_segs
WHERE tablespace_name = 'UNDOTBS1'
AND segment_id = usn;
/*
SEGMENT_NAME|XACTS|STATUS
_SYSSMU102$|1|PENDING OFFLINE
*/
--See it is in "PENDING OFFLINE" status until the transaction that is using it ends.
--See all the rollback info
SELECT n.NAME, s.status, s.extents, s.rssize, s.hwmsize, s.xacts
FROM v$rollname n, v$rollstat s
WHERE n.usn = s.usn;
/*
NAME|STATUS|EXTENTS|RSSIZE|HWMSIZE|XACTS
SYSTEM|ONLINE|6|385024|385024|0
_SYSSMU102$|PENDING OFFLINE|42|42065920|42065920|1
_SYSSMU262$|ONLINE|4|253952|253952|0
_SYSSMU263$|ONLINE|2|122880|122880|0
_SYSSMU264$|ONLINE|3|188416|188416|0
_SYSSMU265$|ONLINE|3|188416|188416|0
_SYSSMU266$|ONLINE|4|253952|253952|0
_SYSSMU267$|ONLINE|2|122880|122880|0
_SYSSMU268$|ONLINE|2|122880|122880|0
_SYSSMU269$|ONLINE|2|122880|122880|0
_SYSSMU270$|ONLINE|2|122880|122880|0
_SYSSMU271$|ONLINE|2|122880|122880|0
*/
--Find the active transactions using undo extents
SELECT s.username, t.xidusn, t.ubafil, t.ubablk, t.used_ublk
FROM v$session s, v$transaction t
WHERE s.saddr = t.ses_addr;
/*
USERNAME|XIDUSN|UBAFIL|UBABLK|USED_UBLK
MARDATA|102|30|153176|1
*/
/*
After all active transactions are committed, the status of Undo segment
_SYSSMU102$ is automatically switched from PENDING OFFLINE mode to OFFLINE mode.
PENDING OFFLINE mode does not allow any deletion process of tablespace.
You can delete the tablespace in OFFLINE mode.
If no segment is selected after you execute the SQL statement below,
it means the segment is already switched to OFFLINE mode.
SQL> SELECT SEGMENT_NAME, XACTS, V.STATUS
FROM V$ROLLSTAT V, DBA_ROLLBACK_SEGS
WHERE TABLESPACE_NAME = 'UNDOTBS_02'
AND SEGMENT_ID = USN;
If the segment is selected and XACTS points to zero (0), rollback segment
does not contain any pending transactions, and therefore,
the segment is switched to OFFLINE mode immediately
*/
--Wait for the active transaction to finish then monitor again
SELECT n.NAME, s.status, s.extents, s.rssize, s.hwmsize, s.xacts
FROM v$rollname n, v$rollstat s
WHERE n.usn = s.usn;
NAME|STATUS|EXTENTS|RSSIZE|HWMSIZE|XACTS
SYSTEM|ONLINE|6|385024|385024|0
_SYSSMU262$|ONLINE|5|319488|319488|0
_SYSSMU263$|ONLINE|2|122880|122880|0
_SYSSMU264$|ONLINE|3|188416|188416|0
_SYSSMU265$|ONLINE|3|188416|188416|0
_SYSSMU266$|ONLINE|4|253952|253952|0
_SYSSMU267$|ONLINE|2|122880|122880|0
_SYSSMU268$|ONLINE|2|122880|122880|0
_SYSSMU269$|ONLINE|2|122880|122880|0
_SYSSMU270$|ONLINE|3|188416|188416|0
--As you can see all undo extents of the old undo tablespace UNDOTBS1 are dropped already
--now we can drop the tablespace
DROP TABLESPACE undotbs1 INCLUDING CONTENTS AND DATAFILES ;
Recreate the original configuration :
After that we can create again the original configuration, so recreate the old undo again
and switch to it
ALTER SYSTEM SET undo_tablespace = UNDOTBS1;
--See if there are any active undo extents of UNDOTBS2
SELECT n.NAME, s.status, s.extents, s.rssize, s.hwmsize, s.xacts
FROM v$rollname n, v$rollstat s
WHERE n.usn = s.usn;
NAME|STATUS|EXTENTS|RSSIZE|HWMSIZE|XACTS
SYSTEM|ONLINE|6|385024|385024|0
_SYSSMU1$|ONLINE|2|122880|122880|0
_SYSSMU2$|ONLINE|2|122880|122880|0
_SYSSMU3$|ONLINE|2|122880|122880|0
_SYSSMU4$|ONLINE|2|122880|122880|0
_SYSSMU5$|ONLINE|2|122880|122880|0
_SYSSMU6$|ONLINE|2|122880|122880|0
_SYSSMU7$|ONLINE|2|122880|122880|0
_SYSSMU8$|ONLINE|2|122880|122880|0
_SYSSMU9$|ONLINE|2|122880|122880|0
_SYSSMU10$|ONLINE|2|122880|122880|0
--See if there is any rollback segments of UNDOTBS2
SELECT segment_name, xacts, v.status
FROM v$rollstat v, dba_rollback_segs
WHERE tablespace_name = 'UNDOTBS2'
AND segment_id = usn;
--No rows returned
DROP TABLESPACE undotbs2 INCLUDING CONTENTS AND DATAFILES ;
Friday, January 16, 2009
Saturday, January 3, 2009
Oracle 9, 10g, 11g - Each active session
Oracle 9, 10g, 11g - Each active session
Last updated 04 September 2008 with Streams monitoring
select STATUS, wait_event, QC_SLAVE, PARALLEL_SESS, QC_SID,
SID, USERNAME, OSUSER, MACHINE, TERMINAL,
PROGRAM, LOGON_TIME, SERVER, SPID, PROCESS, SERIAL#,
TYPE, MODULE, ACTION, SCHEMANAME,
CURRENT_USER, TEMP_MB_USED, locks_blocking, locks_not_blocking, waiting_count, holding_count,
IO_block_gets, IO_consistent_gets, IO_physical_reads, IO_block_changes,
IO_consistent_changes,
to_char(PGA_USED_MEM_MB, 'FM99990.09') PGA_USED_MEM_MB,
to_char(PGA_ALLOC_MEM_MB, 'FM99990.09') PGA_ALLOC_MEM_MB,
to_char(PGA_MAX_MEM_MB, 'FM99990.09') PGA_MAX_MEM_MB,
INACTIVITY_DAYS, OPEN_CURSORS, PARAM_OPEN_CURSORS, Param_sess_cached_cursors,
to_char(PERC_OPEN_CURSORS, 'FM99990.09') PERC_OPEN_CURSORS,
to_char(open_cursors_and_cache_closed, 'FM99990.09') open_cursors_and_cache_closed,
PLAN_VARIATIONS,
SQL_HASH_VALUE, trim(to_char(SQL_ADDRESS||' ')) SQL_ADDRESS,
trim(to_char(saddr||' ')) saddr, KILL_SESSION,
START_TRACE, STOP_TRACE,
KILL_UNIX_PROCESS, undo_records, undo_start_time,
trim(STREAM_INFO || ' ' || STREAM_CAPTURE_INFO || ' ' || STREAM_APPLY_READER_INFO || ' ' || STREAM_APPLY_COORDINATOR) stream,
STREAM_CAPTURE_PROBLEM stream_status from (
select a.*
, (select event from v$session_wait where sid = a.sid and not event in ( --select event from perfstat.stats$idle_event
'AQ Proxy Cleanup Wait',
'ASM background timer',
'DBRM Logical Idle Wait',
'DIAG idle wait',
'EMON idle wait',
'EMON slave idle wait',
'IORM Scheduler Slave Idle Wait',
'KSV master wait',
'LNS ASYNC archive log',
'LNS ASYNC dest activation',
'LNS ASYNC end of log',
'LogMiner: client waiting for transaction',
'LogMiner: generic process sleep',
'LogMiner: reader waiting for more redo',
'LogMiner: slave waiting for activate message',
'LogMiner: waiting for processes to soft detach',
'LogMiner: wakeup event for builder',
'LogMiner: wakeup event for preparer',
'LogMiner: wakeup event for reader',
'MRP redo arrival',
'Null event',
'PING',
'PX Deq Credit: need buffer',
'PX Deq Credit: send blkd',
'PX Deq: Execute Reply',
'PX Deq: Execution Msg',
'PX Deq: Par Recov Execute',
'PX Deq: Signal ACK',
'PX Deq: Table Q Normal',
'PX Deq: Table Q Sample',
'PX Deque wait',
'PX Idle Wait',
'Queue Monitor Shutdown Wait',
'Queue Monitor Slave Wait',
'Queue Monitor Wait',
'SQL*Net message from client',
'SQL*Net message to client',
'SQL*Net more data from client',
'STREAMS apply coord waiting for slave message',
'STREAMS apply slave idle wait',
'STREAMS apply slave waiting for coord message',
'STREAMS capture process filter callback wait for ruleset',
'STREAMS fetch slave waiting for txns',
'STREAMS waiting for subscribers to catch up',
'Space Manager: slave idle wait',
'Streams AQ: RAC qmn coordinator idle wait',
'Streams AQ: deallocate messages from Streams Pool',
'Streams AQ: delete acknowledged messages',
'Streams AQ: qmn coordinator idle wait',
'Streams AQ: qmn slave idle wait',
'Streams AQ: waiting for messages in the queue',
'Streams AQ: waiting for time management or cleanup tasks',
'Streams capture: waiting for archive log',
'Streams fetch slave: waiting for txns',
'class slave wait',
'client message',
'cmon timer',
'dispatcher timer',
'fbar timer',
'gcs for action',
'gcs remote message',
'ges remote message',
'i/o slave wait',
'jobq slave wait',
'knlqdeq',
'lock manager wait for remote message',
'master wait',
'null event',
'parallel query dequeue',
'parallel recovery coordinator waits for slave cleanup',
'parallel recovery slave idle wait',
'parallel recovery slave next change',
'parallel recovery slave wait for change',
'pipe get',
'pmon timer',
'pool server timer',
'queue messages',
'rdbms ipc message',
'slave wait',
'smon timer',
'virtual circuit status',
'wait for activate message',
'wait for unread message on broadcast channel',
'wakeup event for builder',
'wakeup event for preparer',
'wakeup event for reader',
'wakeup time manager',
'watchdog main loop'
)) wait_event
, (select decode(a.sid, m.sid, '************', '') from v$mystat m where rownum=1) current_user
, ('begin '|| '/*Spid is '||spid||'*/ '||' dbms_system.set_sql_trace_in_session('||sid||', '||serial#||', TRUE); end;') start_trace
, ('begin '|| '/*Spid is '||spid||'*/ '||' dbms_system.set_sql_trace_in_session('||sid||', '||serial#||', FALSE); end;') stop_trace
, ('ALTER SYSTEM DISCONNECT SESSION ''' || sid ||','||serial#||''' IMMEDIATE/*spid='||spid||'*/') kill_session
, ('kill -9 '||spid) kill_unix_process
, (select count(*) from v$lock where sid = a.sid and block != 0) locks_blocking
, (select count(*) from v$lock where sid = a.sid and block = 0) locks_not_blocking
, (open_cursors * 100 / param_open_cursors) perc_open_cursors
--Is the session using a query with a variated plan?
, (select count(*) from (
select hash_value, count(*) from (
select hash_value, plan_hash_value from v$sql group by hash_value, plan_hash_value
) group by hash_value having count(*) > 1
) where hash_value = sql_hash_value) plan_variations
-- R O L L B A C K
, (select decode(sort_space_mb, null, 'No temporary used',
sort_space_mb || 'MB, ' || to_char(sort_space_mb * 100 / (sum(bytes_used)/1024/1024), 'FM90.99')||'% of used, '||
to_char(sort_space_mb * 100 / (sum(bytes_used + bytes_free)/1024/1024), 'FM90.99')||'% of ' || (sum(bytes_used + bytes_free)/1024/1024) ||'MB')
from v$temp_space_header) temp_MB_used
from (
select
s.status, s.saddr
, nvl((select decode(px.qcinst_id,NULL, 'Master(QC)', 'Slave') from v$px_session px where px.sid = s.sid), 'Master') QC_Slave
, (select decode(count(*), 0, 0, count(*)-1) from v$px_session px where px.qcsid=(select qcsid from v$px_session where sid =s.sid)) parallel_sess
, (select decode(px.qcinst_id, NULL ,to_char(s.sid) ,px.qcsid) from v$px_session px where px.sid = s.sid) QC_SID
, (select spid from v$process where addr = paddr) spid
, (select value from v$parameter where name = 'open_cursors') param_open_cursors
, (select value from v$parameter where name = 'session_cached_cursors') Param_sess_cached_cursors
, s.sid, decode(s.username, null, 'Server process', s.username) username
, osuser, machine, terminal, program
, logon_time, to_char((last_call_et / 86400), 'FM99990.09') inactivity_days, server, process, s.serial#, type, s.module, s.action,
resource_consumer_group,
sql_hash_value, sql_address, schemaname
--ORACLE 8 MUST COMMENT ALL begin
, (select pga_used_mem/1024/1024 from v$process where addr = paddr) pga_used_mem_MB
, (select pga_alloc_mem/1024/1024 from v$process where addr = paddr) pga_alloc_mem_MB
, (select pga_max_mem/1024/1024 from v$process where addr = paddr) pga_max_mem_MB
--ORACLE 8 MUST COMMENT All end
, (select sum(V$SORT_USAGE.blocks *
--(select value from v$parameter where upper(name) = 'DB_BLOCK_SIZE')
--ORACLE 8 MUST COMMENT THIS LINE BELOW AND ENABLE THE ABOVE
dba_tablespaces.block_size
)/1024/1024 from V$SORT_USAGE, dba_tablespaces
where dba_tablespaces.tablespace_name = V$SORT_USAGE.tablespace and V$SORT_USAGE.session_addr = s.saddr) sort_space_MB
, (select a.value from v$sesstat a, v$statname b where a.statistic# = b.statistic#
and b.name = 'opened cursors current' and a.sid = s.sid) open_cursors
, (select count(*) from v$open_cursor where sid=s.sid) open_cursors_and_cache_closed
, V$SESS_IO.block_gets IO_block_gets, V$SESS_IO.consistent_gets IO_consistent_gets
, V$SESS_IO.physical_reads IO_physical_reads, V$SESS_IO.block_changes IO_block_changes
, V$SESS_IO.consistent_changes IO_consistent_changes
, (select count(*) from DBA_WAITERS where waiting_session = s.sid) waiting_count
, (select count(*) from DBA_WAITERS where holding_session = s.sid) holding_count
, (select sum(used_urec) from V$TRANSACTION where s.saddr = ses_addr) undo_records
, (select min(start_time) from V$TRANSACTION where s.saddr = ses_addr) undo_start_time
/* stream */
, (select decode(module, 'STREAMS', module||', ' || action, null) from v$session where sid=s.sid) STREAM_INFO
/* stream capture */
, (select state || ', [' || CAPTURE_NAME || ' capt. name], [' || ((SYSDATE - CAPTURE_MESSAGE_CREATE_TIME)*86400) || '/' ||
((SYSDATE - CAPTURE_TIME)*86400 || ' latency sec]') from V$STREAMS_CAPTURE where sid=s.sid)
STREAM_CAPTURE_INFO
, (select decode(state, 'CAPTURING CHANGES', 0, 1) from V$STREAMS_CAPTURE where sid=s.sid)
STREAM_CAPTURE_PROBLEM
, (select '[Apply status: ' || DECODE(ap.APPLY_CAPTURED, 'YES','Captured LCRS', 'NO','User-enqueued messages','UNKNOWN') || ']' ||
'[Program: ' || SUBSTR(s.PROGRAM,INSTR(S.PROGRAM,'(')+1,4) || ']'
from V$STREAMS_APPLY_READER, DBA_APPLY ap
where SID = s.SID AND SERIAL# = s.SERIAL# and V$STREAMS_APPLY_READER.APPLY_NAME = ap.APPLY_NAME)
STREAM_APPLY_READER_INFO
, (SELECT 'Apply Coordinator: ' || apply_name || ', ' || c.state || ', process: ' || substr(s.program,instr(s.program,'(')+1,4)
FROM v$streams_apply_coordinator c where c.sid = s.sid and c.serial# = s.serial#)
STREAM_APPLY_COORDINATOR
from
v$session s, V$SESS_IO
--where not username is null --avoid Oracle processes
where V$SESS_IO.sid (+)= s.sid
) a
) b
Last updated 04 September 2008 with Streams monitoring
select STATUS, wait_event, QC_SLAVE, PARALLEL_SESS, QC_SID,
SID, USERNAME, OSUSER, MACHINE, TERMINAL,
PROGRAM, LOGON_TIME, SERVER, SPID, PROCESS, SERIAL#,
TYPE, MODULE, ACTION, SCHEMANAME,
CURRENT_USER, TEMP_MB_USED, locks_blocking, locks_not_blocking, waiting_count, holding_count,
IO_block_gets, IO_consistent_gets, IO_physical_reads, IO_block_changes,
IO_consistent_changes,
to_char(PGA_USED_MEM_MB, 'FM99990.09') PGA_USED_MEM_MB,
to_char(PGA_ALLOC_MEM_MB, 'FM99990.09') PGA_ALLOC_MEM_MB,
to_char(PGA_MAX_MEM_MB, 'FM99990.09') PGA_MAX_MEM_MB,
INACTIVITY_DAYS, OPEN_CURSORS, PARAM_OPEN_CURSORS, Param_sess_cached_cursors,
to_char(PERC_OPEN_CURSORS, 'FM99990.09') PERC_OPEN_CURSORS,
to_char(open_cursors_and_cache_closed, 'FM99990.09') open_cursors_and_cache_closed,
PLAN_VARIATIONS,
SQL_HASH_VALUE, trim(to_char(SQL_ADDRESS||' ')) SQL_ADDRESS,
trim(to_char(saddr||' ')) saddr, KILL_SESSION,
START_TRACE, STOP_TRACE,
KILL_UNIX_PROCESS, undo_records, undo_start_time,
trim(STREAM_INFO || ' ' || STREAM_CAPTURE_INFO || ' ' || STREAM_APPLY_READER_INFO || ' ' || STREAM_APPLY_COORDINATOR) stream,
STREAM_CAPTURE_PROBLEM stream_status from (
select a.*
, (select event from v$session_wait where sid = a.sid and not event in ( --select event from perfstat.stats$idle_event
'AQ Proxy Cleanup Wait',
'ASM background timer',
'DBRM Logical Idle Wait',
'DIAG idle wait',
'EMON idle wait',
'EMON slave idle wait',
'IORM Scheduler Slave Idle Wait',
'KSV master wait',
'LNS ASYNC archive log',
'LNS ASYNC dest activation',
'LNS ASYNC end of log',
'LogMiner: client waiting for transaction',
'LogMiner: generic process sleep',
'LogMiner: reader waiting for more redo',
'LogMiner: slave waiting for activate message',
'LogMiner: waiting for processes to soft detach',
'LogMiner: wakeup event for builder',
'LogMiner: wakeup event for preparer',
'LogMiner: wakeup event for reader',
'MRP redo arrival',
'Null event',
'PING',
'PX Deq Credit: need buffer',
'PX Deq Credit: send blkd',
'PX Deq: Execute Reply',
'PX Deq: Execution Msg',
'PX Deq: Par Recov Execute',
'PX Deq: Signal ACK',
'PX Deq: Table Q Normal',
'PX Deq: Table Q Sample',
'PX Deque wait',
'PX Idle Wait',
'Queue Monitor Shutdown Wait',
'Queue Monitor Slave Wait',
'Queue Monitor Wait',
'SQL*Net message from client',
'SQL*Net message to client',
'SQL*Net more data from client',
'STREAMS apply coord waiting for slave message',
'STREAMS apply slave idle wait',
'STREAMS apply slave waiting for coord message',
'STREAMS capture process filter callback wait for ruleset',
'STREAMS fetch slave waiting for txns',
'STREAMS waiting for subscribers to catch up',
'Space Manager: slave idle wait',
'Streams AQ: RAC qmn coordinator idle wait',
'Streams AQ: deallocate messages from Streams Pool',
'Streams AQ: delete acknowledged messages',
'Streams AQ: qmn coordinator idle wait',
'Streams AQ: qmn slave idle wait',
'Streams AQ: waiting for messages in the queue',
'Streams AQ: waiting for time management or cleanup tasks',
'Streams capture: waiting for archive log',
'Streams fetch slave: waiting for txns',
'class slave wait',
'client message',
'cmon timer',
'dispatcher timer',
'fbar timer',
'gcs for action',
'gcs remote message',
'ges remote message',
'i/o slave wait',
'jobq slave wait',
'knlqdeq',
'lock manager wait for remote message',
'master wait',
'null event',
'parallel query dequeue',
'parallel recovery coordinator waits for slave cleanup',
'parallel recovery slave idle wait',
'parallel recovery slave next change',
'parallel recovery slave wait for change',
'pipe get',
'pmon timer',
'pool server timer',
'queue messages',
'rdbms ipc message',
'slave wait',
'smon timer',
'virtual circuit status',
'wait for activate message',
'wait for unread message on broadcast channel',
'wakeup event for builder',
'wakeup event for preparer',
'wakeup event for reader',
'wakeup time manager',
'watchdog main loop'
)) wait_event
, (select decode(a.sid, m.sid, '************', '') from v$mystat m where rownum=1) current_user
, ('begin '|| '/*Spid is '||spid||'*/ '||' dbms_system.set_sql_trace_in_session('||sid||', '||serial#||', TRUE); end;') start_trace
, ('begin '|| '/*Spid is '||spid||'*/ '||' dbms_system.set_sql_trace_in_session('||sid||', '||serial#||', FALSE); end;') stop_trace
, ('ALTER SYSTEM DISCONNECT SESSION ''' || sid ||','||serial#||''' IMMEDIATE/*spid='||spid||'*/') kill_session
, ('kill -9 '||spid) kill_unix_process
, (select count(*) from v$lock where sid = a.sid and block != 0) locks_blocking
, (select count(*) from v$lock where sid = a.sid and block = 0) locks_not_blocking
, (open_cursors * 100 / param_open_cursors) perc_open_cursors
--Is the session using a query with a variated plan?
, (select count(*) from (
select hash_value, count(*) from (
select hash_value, plan_hash_value from v$sql group by hash_value, plan_hash_value
) group by hash_value having count(*) > 1
) where hash_value = sql_hash_value) plan_variations
-- R O L L B A C K
, (select decode(sort_space_mb, null, 'No temporary used',
sort_space_mb || 'MB, ' || to_char(sort_space_mb * 100 / (sum(bytes_used)/1024/1024), 'FM90.99')||'% of used, '||
to_char(sort_space_mb * 100 / (sum(bytes_used + bytes_free)/1024/1024), 'FM90.99')||'% of ' || (sum(bytes_used + bytes_free)/1024/1024) ||'MB')
from v$temp_space_header) temp_MB_used
from (
select
s.status, s.saddr
, nvl((select decode(px.qcinst_id,NULL, 'Master(QC)', 'Slave') from v$px_session px where px.sid = s.sid), 'Master') QC_Slave
, (select decode(count(*), 0, 0, count(*)-1) from v$px_session px where px.qcsid=(select qcsid from v$px_session where sid =s.sid)) parallel_sess
, (select decode(px.qcinst_id, NULL ,to_char(s.sid) ,px.qcsid) from v$px_session px where px.sid = s.sid) QC_SID
, (select spid from v$process where addr = paddr) spid
, (select value from v$parameter where name = 'open_cursors') param_open_cursors
, (select value from v$parameter where name = 'session_cached_cursors') Param_sess_cached_cursors
, s.sid, decode(s.username, null, 'Server process', s.username) username
, osuser, machine, terminal, program
, logon_time, to_char((last_call_et / 86400), 'FM99990.09') inactivity_days, server, process, s.serial#, type, s.module, s.action,
resource_consumer_group,
sql_hash_value, sql_address, schemaname
--ORACLE 8 MUST COMMENT ALL begin
, (select pga_used_mem/1024/1024 from v$process where addr = paddr) pga_used_mem_MB
, (select pga_alloc_mem/1024/1024 from v$process where addr = paddr) pga_alloc_mem_MB
, (select pga_max_mem/1024/1024 from v$process where addr = paddr) pga_max_mem_MB
--ORACLE 8 MUST COMMENT All end
, (select sum(V$SORT_USAGE.blocks *
--(select value from v$parameter where upper(name) = 'DB_BLOCK_SIZE')
--ORACLE 8 MUST COMMENT THIS LINE BELOW AND ENABLE THE ABOVE
dba_tablespaces.block_size
)/1024/1024 from V$SORT_USAGE, dba_tablespaces
where dba_tablespaces.tablespace_name = V$SORT_USAGE.tablespace and V$SORT_USAGE.session_addr = s.saddr) sort_space_MB
, (select a.value from v$sesstat a, v$statname b where a.statistic# = b.statistic#
and b.name = 'opened cursors current' and a.sid = s.sid) open_cursors
, (select count(*) from v$open_cursor where sid=s.sid) open_cursors_and_cache_closed
, V$SESS_IO.block_gets IO_block_gets, V$SESS_IO.consistent_gets IO_consistent_gets
, V$SESS_IO.physical_reads IO_physical_reads, V$SESS_IO.block_changes IO_block_changes
, V$SESS_IO.consistent_changes IO_consistent_changes
, (select count(*) from DBA_WAITERS where waiting_session = s.sid) waiting_count
, (select count(*) from DBA_WAITERS where holding_session = s.sid) holding_count
, (select sum(used_urec) from V$TRANSACTION where s.saddr = ses_addr) undo_records
, (select min(start_time) from V$TRANSACTION where s.saddr = ses_addr) undo_start_time
/* stream */
, (select decode(module, 'STREAMS', module||', ' || action, null) from v$session where sid=s.sid) STREAM_INFO
/* stream capture */
, (select state || ', [' || CAPTURE_NAME || ' capt. name], [' || ((SYSDATE - CAPTURE_MESSAGE_CREATE_TIME)*86400) || '/' ||
((SYSDATE - CAPTURE_TIME)*86400 || ' latency sec]') from V$STREAMS_CAPTURE where sid=s.sid)
STREAM_CAPTURE_INFO
, (select decode(state, 'CAPTURING CHANGES', 0, 1) from V$STREAMS_CAPTURE where sid=s.sid)
STREAM_CAPTURE_PROBLEM
, (select '[Apply status: ' || DECODE(ap.APPLY_CAPTURED, 'YES','Captured LCRS', 'NO','User-enqueued messages','UNKNOWN') || ']' ||
'[Program: ' || SUBSTR(s.PROGRAM,INSTR(S.PROGRAM,'(')+1,4) || ']'
from V$STREAMS_APPLY_READER, DBA_APPLY ap
where SID = s.SID AND SERIAL# = s.SERIAL# and V$STREAMS_APPLY_READER.APPLY_NAME = ap.APPLY_NAME)
STREAM_APPLY_READER_INFO
, (SELECT 'Apply Coordinator: ' || apply_name || ', ' || c.state || ', process: ' || substr(s.program,instr(s.program,'(')+1,4)
FROM v$streams_apply_coordinator c where c.sid = s.sid and c.serial# = s.serial#)
STREAM_APPLY_COORDINATOR
from
v$session s, V$SESS_IO
--where not username is null --avoid Oracle processes
where V$SESS_IO.sid (+)= s.sid
) a
) b
sessions script 2
See any locking session
select * from dba_locks
order by blocking_others
Use utllockt.sql to see locking sessions
Remember that catblock.sql should have ran, you can verify this by using:
select * from dba_locks
sqlplus (windows)>@?\rdbms\admin\utllockt
sqlplus (unix)>@?/rdbms/admin/utllockt
WAITING_SESSION LOCK_TYPE MODE_REQUESTED MODE_HELD LOCK_ID1 LOCK_ID2
----------------- ----------------- -------------- -------------- ----------------- -----------------
20 None
9 DML Exclusive Exclusive 54132 0
In this case the session 20 is locking session 9, so kill session 20
Library cache pin locks
SELECT sid, event, p1raw, seconds_in_wait, wait_time
FROM sys.v_$session_wait
WHERE event = 'library cache pin'
SELECT 'alter system kill session ''' || s.sid || ',' || s.serial# || ''';'
, 'kill -9 ' || spid
FROM x$kglpn p, v$session s, v$process
WHERE p.kglpnuse=s.saddr
AND kglpnhdl='DA741F24'
and v$process.addr = s.paddr
A session is hang, kill anyone interfering
SELECT *
FROM v$access
WHERE OBJECT IN (SELECT object_name
FROM dba_objects
WHERE object_id IN (SELECT object_id
FROM v$locked_object
WHERE session_id = 32))
select 'ALTER SYSTEM DISCONNECT SESSION ''' || sid || ', ' || v$session.serial# ||
''' immediate/*spid=' || spid || '*/'
from v$session, v$process
where sid in (
select sid from v$access
where object = 'VTCONNECTORSTATE'
group by sid
)
and v$process.addr = v$session.paddr
select * from (
SELECT s.schemaname, p.username, s.sid, p.pid, p.spid, s.username ora,
DECODE(l2.type, 'TX','TRANSACTION ROW-LEVEL', 'TS','TEMPORARY SEGMENT ', 'TD','TABLE LOCK',
'TM','ROW LOCK', l2.type ) vlock,
DECODE(l2.type, 'TX','DML LOCK', 'TS','TEMPORARY SEGMENT', 'TD',DECODE(l2.lmode+l2.request,
4,'PARSE ' || u.name || '.' || o.name, 6,'DDL', l2.lmode+l2.request), 'TM','DML ' || u.name ||
'.' || o.name, l2.type ) type,
DECODE(l2.lmode+l2.request, 2,'RS', 3 ,'RX', 4 ,'S', 5 ,'SRX', 6 ,'X', l2.lmode+l2.request ) lmode ,
DECODE(l2.request, 0,NULL, 'WAIT') wait
FROM v$process p, v$_lock l1, v$lock l2, v$resource r, sys.obj$ o, sys.user$ u, v$session s
WHERE s.paddr = p.addr
AND s.saddr = l1.saddr
AND l1.raddr = r.addr
AND l2.addr = l1.laddr
AND l2.type <> 'MR'
AND l2.type <> 'RT'
AND r.id1 = o.obj# (+)
AND o.owner# = u.user# (+)
)
Lock simulation
The updates performed in this example does not modify the actual values!
select id, de_VC1 from prova where id in (193556, 196756)
ID DE_VC1
---------- --------------------
193556 mon
196756 mon
session 1, sid 145>update prova set de_VC1 = 'sess1' where id = 193556;
1 row updated.
SELECT v$session.username, dba_locks.*
FROM dba_locks, v$session
WHERE v$session.SID = dba_locks.session_id AND session_id = 145
username session_id lock_type mode_held mode_requested lock_id1 lock_id2 last_convert blocking_others
ALDO 145 DML Row-X (SX) None 53176 0 270 Not Blocking
ALDO 145 Transaction Exclusive None 196615 676 270 Not Blocking
session 2, sid 156>update prova set de_VC1 = 'sess2' where id = 196756;
1 row updated.
SELECT v$session.username, dba_locks.*
FROM dba_locks, v$session
WHERE v$session.SID = dba_locks.session_id AND session_id = 156
username session_id lock_type mode_held mode_requested lock_id1 lock_id2 last_convert blocking_others
ALDO 156 DML Row-X (SX) None 53176 0 270 Not Blocking
ALDO 156 Transaction Exclusive None 262191 680 270 Not Blocking
session 1, sid 145>update prova set de_VC1 = 'sess1' where id = 196756;
--session hang waiting
SELECT v$session.username, dba_locks.*
FROM dba_locks, v$session
WHERE v$session.SID = dba_locks.session_id AND session_id IN (145, 156)
ORDER BY session_id
username session_id lock_type mode_held mode_requested lock_id1 lock_id2 last_convert blocking_others
ALDO 145 Transaction Exclusive None 196615 676 883 Not Blocking
ALDO 145 DML Row-X (SX) None 53176 0 883 Not Blocking
ALDO 145 Transaction None Exclusive 262191 680 81 Not Blocking
ALDO 156 Transaction Exclusive None 262191 680 349 Blocking
ALDO 156 DML Row-X (SX) None 53176 0 349 Not Blocking
session 2, sid 156>update prova set de_VC1 = 'sess2' where id = 193556;
--session hang waiting
session 1, sid 145>ERROR at line 1:
ORA-00060: deadlock detected while waiting for resource
session 2, sid 156>--continue waiting
SELECT v$session.username, dba_locks.*
FROM dba_locks, v$session
WHERE v$session.SID = dba_locks.session_id AND session_id IN (145, 156)
ORDER BY session_id
username session_id lock_type mode_held mode_requested lock_id1 lock_id2 last_convert blocking_others
ALDO 145 Transaction Exclusive None 196615 676 1246 Blocking
ALDO 145 DML Row-X (SX) None 53176 0 1246 Not Blocking
ALDO 156 Transaction Exclusive None 262191 680 712 Not Blocking
ALDO 156 Transaction None Exclusive 196615 676 9 Not Blocking
ALDO 156 DML Row-X (SX) None 53176 0 712 Not Blocking
Trace generated
Dump file c:\oracle\product\10.2.0\admin\al12\udump\al12_ora_5428.trc
Wed Feb 22 11:27:34 2006
ORACLE V10.2.0.1.0 - Production vsnsta=0
vsnsql=14 vsnxtr=3
Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Production
With the Partitioning, OLAP and Data Mining options
Windows XP Version V5.1 Service Pack 2
CPU : 1 - type 586
Process Affinity : 0x00000000
Memory (Avail/Total): Ph:985M/2046M, Ph+PgF:2957M/3938M, VA:1713M/2047M
Instance name: al12
Redo thread mounted by this instance: 1
Oracle process number: 19
Windows thread id: 5428, image: ORACLE.EXE (SHAD)
*** 2006-02-22 11:27:34.171
*** ACTION NAME:() 2006-02-22 11:27:34.156
*** MODULE NAME:(SQL*Plus) 2006-02-22 11:27:34.156
*** SERVICE NAME:(al12) 2006-02-22 11:27:34.156
*** SESSION ID:(35.38) 2006-02-22 11:27:34.156
DEADLOCK DETECTED
[Transaction Deadlock]
Current SQL statement for this session:
update prova set de_VC1 = 'sess1' where id = 196756 (the session was waiting, then take ORA-00060)
The following deadlock is not an ORACLE error. It is a
deadlock due to user error in the design of an application
or from issuing incorrect ad-hoc SQL. The following
information may aid in determining the deadlock:
Deadlock graph:
---------Blocker(s)-------- ---------Waiter(s)---------
Resource Name process session holds waits process session holds waits
TX-00020021-000005aa 19 35 X 20 46 X
TX-0003001f-000005b4 20 46 X 19 35 X
session 35: DID 0001-0013-00000007 session 46: DID 0001-0014-00000005
session 46: DID 0001-0014-00000005 session 35: DID 0001-0013-00000007
Rows waited on:
Session 46: obj - rowid = 0000CFB8 - AAAM+4AAHAAABAaAAB
(dictionary objn - 53176, file - 7, block - 4122, slot - 1)
Session 35: obj - rowid = 0000CFB8 - AAAM+4AAHAAABAaAAE
(dictionary objn - 53176, file - 7, block - 4122, slot - 4)
Information on the OTHER waiting sessions:
Session 46:
pid=20 serial=30 audsid=4264 user: 55/ALDO
O/S info: user: root, term: D2E7B5729B, ospid: 5276:1080, machine: WORKGROUP\D2E7B5729B
program: sqlplus.exe
application name: SQL*Plus, hash value=3669949024
Current SQL Statement:
update prova set de_VC1 = 'sess2' where id = 193556 (the session may continue waiting if sess1 do nothing)
End of information on OTHER waiting sessions.
===================================================
Get all long running queries
SELECT /*+ rule */
SYSDATE tracciamento, a.SID SID, b.serial# serial, b.last_call_et,
a.event wait_event, b.username username, b.machine machine,
b.program programma, sq.sql_text
FROM v$session_wait a, v$session b, v$sql sq
WHERE event NOT IN
('smon timer',
'pmon timer',
'rdbms ipc message',
'SQL*Net message from client',
'SQL*Net message to client',
'SQL*Net more data to client',
'SQL*Net message from dblink',
'jobq slave wait'
)
AND a.SID = b.SID
AND b.sql_address = sq.address
AND b.last_call_et > 60
AND b.username NOT IN ('SYS', 'SYSTEM', 'EXPDB')
AND b.SID NOT IN (SELECT SID
FROM dba_jobs_running)
ORDER BY b.last_call_et DESC
Master sessions and parallel spawned sessions
col username for a12
col "QC SID" for A6
col SID for A6
col "QC/Slave" for A10
col "Requested DOP" for 9999
col "Actual DOP" for 9999
col "slave set" for A10
set pages 100
select
decode(px.qcinst_id,NULL,username,
' - '||lower(substr(s.program,length(s.program)-4,4) ) ) "Username",
decode(px.qcinst_id,NULL, 'QC', '(Slave)') "QC/Slave" ,
to_char( px.server_set) "Slave Set",
to_char(s.sid) "SID",
decode(px.qcinst_id, NULL ,to_char(s.sid) ,px.qcsid) "QC SID",
px.req_degree "Requested DOP",
px.degree "Actual DOP"
from
v$px_session px,
v$session s
where
px.sid=s.sid (+)
and
px.serial#=s.serial#
order by 5 , 1 desc;
select * from dba_locks
order by blocking_others
Use utllockt.sql to see locking sessions
Remember that catblock.sql should have ran, you can verify this by using:
select * from dba_locks
sqlplus (windows)>@?\rdbms\admin\utllockt
sqlplus (unix)>@?/rdbms/admin/utllockt
WAITING_SESSION LOCK_TYPE MODE_REQUESTED MODE_HELD LOCK_ID1 LOCK_ID2
----------------- ----------------- -------------- -------------- ----------------- -----------------
20 None
9 DML Exclusive Exclusive 54132 0
In this case the session 20 is locking session 9, so kill session 20
Library cache pin locks
SELECT sid, event, p1raw, seconds_in_wait, wait_time
FROM sys.v_$session_wait
WHERE event = 'library cache pin'
SELECT 'alter system kill session ''' || s.sid || ',' || s.serial# || ''';'
, 'kill -9 ' || spid
FROM x$kglpn p, v$session s, v$process
WHERE p.kglpnuse=s.saddr
AND kglpnhdl='DA741F24'
and v$process.addr = s.paddr
A session is hang, kill anyone interfering
SELECT *
FROM v$access
WHERE OBJECT IN (SELECT object_name
FROM dba_objects
WHERE object_id IN (SELECT object_id
FROM v$locked_object
WHERE session_id = 32))
select 'ALTER SYSTEM DISCONNECT SESSION ''' || sid || ', ' || v$session.serial# ||
''' immediate/*spid=' || spid || '*/'
from v$session, v$process
where sid in (
select sid from v$access
where object = 'VTCONNECTORSTATE'
group by sid
)
and v$process.addr = v$session.paddr
select * from (
SELECT s.schemaname, p.username, s.sid, p.pid, p.spid, s.username ora,
DECODE(l2.type, 'TX','TRANSACTION ROW-LEVEL', 'TS','TEMPORARY SEGMENT ', 'TD','TABLE LOCK',
'TM','ROW LOCK', l2.type ) vlock,
DECODE(l2.type, 'TX','DML LOCK', 'TS','TEMPORARY SEGMENT', 'TD',DECODE(l2.lmode+l2.request,
4,'PARSE ' || u.name || '.' || o.name, 6,'DDL', l2.lmode+l2.request), 'TM','DML ' || u.name ||
'.' || o.name, l2.type ) type,
DECODE(l2.lmode+l2.request, 2,'RS', 3 ,'RX', 4 ,'S', 5 ,'SRX', 6 ,'X', l2.lmode+l2.request ) lmode ,
DECODE(l2.request, 0,NULL, 'WAIT') wait
FROM v$process p, v$_lock l1, v$lock l2, v$resource r, sys.obj$ o, sys.user$ u, v$session s
WHERE s.paddr = p.addr
AND s.saddr = l1.saddr
AND l1.raddr = r.addr
AND l2.addr = l1.laddr
AND l2.type <> 'MR'
AND l2.type <> 'RT'
AND r.id1 = o.obj# (+)
AND o.owner# = u.user# (+)
)
Lock simulation
The updates performed in this example does not modify the actual values!
select id, de_VC1 from prova where id in (193556, 196756)
ID DE_VC1
---------- --------------------
193556 mon
196756 mon
session 1, sid 145>update prova set de_VC1 = 'sess1' where id = 193556;
1 row updated.
SELECT v$session.username, dba_locks.*
FROM dba_locks, v$session
WHERE v$session.SID = dba_locks.session_id AND session_id = 145
username session_id lock_type mode_held mode_requested lock_id1 lock_id2 last_convert blocking_others
ALDO 145 DML Row-X (SX) None 53176 0 270 Not Blocking
ALDO 145 Transaction Exclusive None 196615 676 270 Not Blocking
session 2, sid 156>update prova set de_VC1 = 'sess2' where id = 196756;
1 row updated.
SELECT v$session.username, dba_locks.*
FROM dba_locks, v$session
WHERE v$session.SID = dba_locks.session_id AND session_id = 156
username session_id lock_type mode_held mode_requested lock_id1 lock_id2 last_convert blocking_others
ALDO 156 DML Row-X (SX) None 53176 0 270 Not Blocking
ALDO 156 Transaction Exclusive None 262191 680 270 Not Blocking
session 1, sid 145>update prova set de_VC1 = 'sess1' where id = 196756;
--session hang waiting
SELECT v$session.username, dba_locks.*
FROM dba_locks, v$session
WHERE v$session.SID = dba_locks.session_id AND session_id IN (145, 156)
ORDER BY session_id
username session_id lock_type mode_held mode_requested lock_id1 lock_id2 last_convert blocking_others
ALDO 145 Transaction Exclusive None 196615 676 883 Not Blocking
ALDO 145 DML Row-X (SX) None 53176 0 883 Not Blocking
ALDO 145 Transaction None Exclusive 262191 680 81 Not Blocking
ALDO 156 Transaction Exclusive None 262191 680 349 Blocking
ALDO 156 DML Row-X (SX) None 53176 0 349 Not Blocking
session 2, sid 156>update prova set de_VC1 = 'sess2' where id = 193556;
--session hang waiting
session 1, sid 145>ERROR at line 1:
ORA-00060: deadlock detected while waiting for resource
session 2, sid 156>--continue waiting
SELECT v$session.username, dba_locks.*
FROM dba_locks, v$session
WHERE v$session.SID = dba_locks.session_id AND session_id IN (145, 156)
ORDER BY session_id
username session_id lock_type mode_held mode_requested lock_id1 lock_id2 last_convert blocking_others
ALDO 145 Transaction Exclusive None 196615 676 1246 Blocking
ALDO 145 DML Row-X (SX) None 53176 0 1246 Not Blocking
ALDO 156 Transaction Exclusive None 262191 680 712 Not Blocking
ALDO 156 Transaction None Exclusive 196615 676 9 Not Blocking
ALDO 156 DML Row-X (SX) None 53176 0 712 Not Blocking
Trace generated
Dump file c:\oracle\product\10.2.0\admin\al12\udump\al12_ora_5428.trc
Wed Feb 22 11:27:34 2006
ORACLE V10.2.0.1.0 - Production vsnsta=0
vsnsql=14 vsnxtr=3
Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Production
With the Partitioning, OLAP and Data Mining options
Windows XP Version V5.1 Service Pack 2
CPU : 1 - type 586
Process Affinity : 0x00000000
Memory (Avail/Total): Ph:985M/2046M, Ph+PgF:2957M/3938M, VA:1713M/2047M
Instance name: al12
Redo thread mounted by this instance: 1
Oracle process number: 19
Windows thread id: 5428, image: ORACLE.EXE (SHAD)
*** 2006-02-22 11:27:34.171
*** ACTION NAME:() 2006-02-22 11:27:34.156
*** MODULE NAME:(SQL*Plus) 2006-02-22 11:27:34.156
*** SERVICE NAME:(al12) 2006-02-22 11:27:34.156
*** SESSION ID:(35.38) 2006-02-22 11:27:34.156
DEADLOCK DETECTED
[Transaction Deadlock]
Current SQL statement for this session:
update prova set de_VC1 = 'sess1' where id = 196756 (the session was waiting, then take ORA-00060)
The following deadlock is not an ORACLE error. It is a
deadlock due to user error in the design of an application
or from issuing incorrect ad-hoc SQL. The following
information may aid in determining the deadlock:
Deadlock graph:
---------Blocker(s)-------- ---------Waiter(s)---------
Resource Name process session holds waits process session holds waits
TX-00020021-000005aa 19 35 X 20 46 X
TX-0003001f-000005b4 20 46 X 19 35 X
session 35: DID 0001-0013-00000007 session 46: DID 0001-0014-00000005
session 46: DID 0001-0014-00000005 session 35: DID 0001-0013-00000007
Rows waited on:
Session 46: obj - rowid = 0000CFB8 - AAAM+4AAHAAABAaAAB
(dictionary objn - 53176, file - 7, block - 4122, slot - 1)
Session 35: obj - rowid = 0000CFB8 - AAAM+4AAHAAABAaAAE
(dictionary objn - 53176, file - 7, block - 4122, slot - 4)
Information on the OTHER waiting sessions:
Session 46:
pid=20 serial=30 audsid=4264 user: 55/ALDO
O/S info: user: root, term: D2E7B5729B, ospid: 5276:1080, machine: WORKGROUP\D2E7B5729B
program: sqlplus.exe
application name: SQL*Plus, hash value=3669949024
Current SQL Statement:
update prova set de_VC1 = 'sess2' where id = 193556 (the session may continue waiting if sess1 do nothing)
End of information on OTHER waiting sessions.
===================================================
Get all long running queries
SELECT /*+ rule */
SYSDATE tracciamento, a.SID SID, b.serial# serial, b.last_call_et,
a.event wait_event, b.username username, b.machine machine,
b.program programma, sq.sql_text
FROM v$session_wait a, v$session b, v$sql sq
WHERE event NOT IN
('smon timer',
'pmon timer',
'rdbms ipc message',
'SQL*Net message from client',
'SQL*Net message to client',
'SQL*Net more data to client',
'SQL*Net message from dblink',
'jobq slave wait'
)
AND a.SID = b.SID
AND b.sql_address = sq.address
AND b.last_call_et > 60
AND b.username NOT IN ('SYS', 'SYSTEM', 'EXPDB')
AND b.SID NOT IN (SELECT SID
FROM dba_jobs_running)
ORDER BY b.last_call_et DESC
Master sessions and parallel spawned sessions
col username for a12
col "QC SID" for A6
col SID for A6
col "QC/Slave" for A10
col "Requested DOP" for 9999
col "Actual DOP" for 9999
col "slave set" for A10
set pages 100
select
decode(px.qcinst_id,NULL,username,
' - '||lower(substr(s.program,length(s.program)-4,4) ) ) "Username",
decode(px.qcinst_id,NULL, 'QC', '(Slave)') "QC/Slave" ,
to_char( px.server_set) "Slave Set",
to_char(s.sid) "SID",
decode(px.qcinst_id, NULL ,to_char(s.sid) ,px.qcsid) "QC SID",
px.req_degree "Requested DOP",
px.degree "Actual DOP"
from
v$px_session px,
v$session s
where
px.sid=s.sid (+)
and
px.serial#=s.serial#
order by 5 , 1 desc;
This script produces a very detailed report on Current Lock Waits in the database including a list of holding and waiting sessions and the types of locks they are holding.
set serveroutput on size 10000
declare
cursor c1 is
select * from v$lock where request != 0
order by id1, id2;
wid1 number := -999999;
wid2 number := -999999;
wholder_detail varchar2(200);
v_err_msg varchar2(80);
wsid number(5);
wstep number(2);
wtype varchar2(10);
wobject_name varchar2(180);
wobject_name1 varchar2(80);
wlock_type varchar2(50);
w_lastcallet varchar2(11);
h_lastcallet varchar2(11);
begin
for c1_rec in c1 loop
if c1_rec.id1 = wid1 and c1_rec.id2 = wid2 then
null;
else
wstep := 10;
select sid , type into wsid , wtype
from v$lock
where id1 = c1_rec.id1
and id2 = c1_rec.id2
and request = 0
and lmode != 4;
dbms_output.put_line(' ');
wstep := 20;
select 'Holder DBU: '||s.username ||' OSU: '||s.osuser ||' DBP:'||p.spid||' APP: '|| s.process ||
' SID:' || s.sid || ' Status: ' || s.status ||
' (' || floor(last_call_et/3600)||':'||
floor(mod(last_call_et,3600)/60)||':'||
mod(mod(last_call_et,3600),60) ||
') Module:'|| module ||
' AppSrvr: ' || substr(replace(machine,'LOCALHOST',null),1,15)
into wholder_detail
from v$session s, v$process p
where s.sid= wsid
and s.paddr = p.addr;
dbms_output.put_line(wholder_detail);
begin
select decode(wtype,'TX', 'Transaction',
'DL', 'DDL Lock',
'MR', 'Media Recovery',
'RT', 'Redo Thread',
'UN', 'User Name',
'TX', 'Transaction',
'TM', 'DML',
'UL', 'PL/SQL User Lock',
'DX', 'Distributed Xaction',
'CF', 'Control File',
'IS', 'Instance State',
'FS', 'File Set',
'IR', 'Instance Recovery',
'ST', 'Disk Space Transaction',
'TS', 'Temp Segment',
'IV', 'Library Cache Invalida-tion',
'LS', 'Log Start or Switch',
'RW', 'Row Wait',
'SQ', 'Sequence Number',
'TE', 'Extend Table',
'TT', 'Temp Table',
'Un-Known Type of Lock')
into wlock_type
from dual;
declare
cursor c3 is
select object_id from v$locked_object
where session_id = wsid;
begin
wobject_name := '';
for c3_rec in c3 loop
select object_type||': '||owner||'.'||object_name
into wobject_name
from dba_objects
where object_id = c3_rec.object_id;
wobject_name := wobject_name ||' '||wobject_name1;
end loop;
exception
when others then
wobject_name := wobject_name ||' No Object Found';
end;
dbms_output.put_line('Lock Held: '||wlock_type||' for Object :'||wobject_name);
exception
when no_data_found then
dbms_output.put_line('Lock Held: '||wlock_type||' No object found in DBA Objects');
end;
end if;
wstep := 30;
select '.... Requestor DBU: '||s.username ||' OSU: '||s.osuser ||' DBP:'||p.spid||' APP: '|| s.process ||
' SID:' || s.sid || ' Status: ' || s.status ||
' (' || floor(last_call_et/3600)||':'||
floor(mod(last_call_et,3600)/60)||':'||
mod(mod(last_call_et,3600),60) ||
') Module:'|| module ||
' AppSrvr: ' || substr(replace(machine,'LOCALHOST\',null),1,15)
into wholder_detail
from v$session s, v$process p
where s.sid= c1_rec.sid
and s.paddr = p.addr;
dbms_output.put_line(wholder_detail);
wid1 := c1_rec.id1;
wid2 := c1_rec.id2;
end loop;
if wid1 = -999999 then
wstep := 40;
dbms_output.put_line('No one requesting locks held by others');
end if;
exception
when others then
v_err_msg := (sqlerrm ||' '|| sqlcode||' step='||to_char(wstep));
DBMS_OUTPUT.PUT_LINE(v_err_msg);
end;
/
set serveroutput on size 10000
declare
cursor c1 is
select * from v$lock where request != 0
order by id1, id2;
wid1 number := -999999;
wid2 number := -999999;
wholder_detail varchar2(200);
v_err_msg varchar2(80);
wsid number(5);
wstep number(2);
wtype varchar2(10);
wobject_name varchar2(180);
wobject_name1 varchar2(80);
wlock_type varchar2(50);
w_lastcallet varchar2(11);
h_lastcallet varchar2(11);
begin
for c1_rec in c1 loop
if c1_rec.id1 = wid1 and c1_rec.id2 = wid2 then
null;
else
wstep := 10;
select sid , type into wsid , wtype
from v$lock
where id1 = c1_rec.id1
and id2 = c1_rec.id2
and request = 0
and lmode != 4;
dbms_output.put_line(' ');
wstep := 20;
select 'Holder DBU: '||s.username ||' OSU: '||s.osuser ||' DBP:'||p.spid||' APP: '|| s.process ||
' SID:' || s.sid || ' Status: ' || s.status ||
' (' || floor(last_call_et/3600)||':'||
floor(mod(last_call_et,3600)/60)||':'||
mod(mod(last_call_et,3600),60) ||
') Module:'|| module ||
' AppSrvr: ' || substr(replace(machine,'LOCALHOST',null),1,15)
into wholder_detail
from v$session s, v$process p
where s.sid= wsid
and s.paddr = p.addr;
dbms_output.put_line(wholder_detail);
begin
select decode(wtype,'TX', 'Transaction',
'DL', 'DDL Lock',
'MR', 'Media Recovery',
'RT', 'Redo Thread',
'UN', 'User Name',
'TX', 'Transaction',
'TM', 'DML',
'UL', 'PL/SQL User Lock',
'DX', 'Distributed Xaction',
'CF', 'Control File',
'IS', 'Instance State',
'FS', 'File Set',
'IR', 'Instance Recovery',
'ST', 'Disk Space Transaction',
'TS', 'Temp Segment',
'IV', 'Library Cache Invalida-tion',
'LS', 'Log Start or Switch',
'RW', 'Row Wait',
'SQ', 'Sequence Number',
'TE', 'Extend Table',
'TT', 'Temp Table',
'Un-Known Type of Lock')
into wlock_type
from dual;
declare
cursor c3 is
select object_id from v$locked_object
where session_id = wsid;
begin
wobject_name := '';
for c3_rec in c3 loop
select object_type||': '||owner||'.'||object_name
into wobject_name
from dba_objects
where object_id = c3_rec.object_id;
wobject_name := wobject_name ||' '||wobject_name1;
end loop;
exception
when others then
wobject_name := wobject_name ||' No Object Found';
end;
dbms_output.put_line('Lock Held: '||wlock_type||' for Object :'||wobject_name);
exception
when no_data_found then
dbms_output.put_line('Lock Held: '||wlock_type||' No object found in DBA Objects');
end;
end if;
wstep := 30;
select '.... Requestor DBU: '||s.username ||' OSU: '||s.osuser ||' DBP:'||p.spid||' APP: '|| s.process ||
' SID:' || s.sid || ' Status: ' || s.status ||
' (' || floor(last_call_et/3600)||':'||
floor(mod(last_call_et,3600)/60)||':'||
mod(mod(last_call_et,3600),60) ||
') Module:'|| module ||
' AppSrvr: ' || substr(replace(machine,'LOCALHOST\',null),1,15)
into wholder_detail
from v$session s, v$process p
where s.sid= c1_rec.sid
and s.paddr = p.addr;
dbms_output.put_line(wholder_detail);
wid1 := c1_rec.id1;
wid2 := c1_rec.id2;
end loop;
if wid1 = -999999 then
wstep := 40;
dbms_output.put_line('No one requesting locks held by others');
end if;
exception
when others then
v_err_msg := (sqlerrm ||' '|| sqlcode||' step='||to_char(wstep));
DBMS_OUTPUT.PUT_LINE(v_err_msg);
end;
/
Friday, January 2, 2009
Fast Index Rebuild.
An index should be considered for rebuilding under any of the following conditions:
* The percentage of deleted rows exceeds 30% of the total, i.e. if
del_lf_rows / lf_rows > 0.3.
* If the ‘HEIGHT’ is greater than 4.
* If the number of rows in the index (‘LF_ROWS’) is significantly smaller than ‘LF_BLKS’ this can indicate a large number of deletes, indicating that the index should be rebuilt.
Fast Index Rebuild.
The REBUILD option of the ALTER INDEX statement is executed to quickly rebuild an index using the existing index instead of the table:
alter index emp_idx1 rebuild parallel
tablespace user_tblspc1
storage (pctincrease 0);
Index altered.
Any Modifications to the STORAGE clause can be made at this time and the parallel option can also be used if parallelism is enabled in your database.
Using the REBUILD option of the ALTER INDEX statement for quickly rebuilding an index requires the existing index instead of the table. So necessary space should be available to store both the indexes during the REBUILD operation.
You can also REBUILD online clause to allow DML operations on the table. Index Rebuild online is not applicable for Bitmap indexes or for indexes that enfore referential Integirity Constraints.
This code genenates a script to rebuld all the indexes with height greater than 3 for all the users except for SYS user. The script needs to be executed from SYS schema. This can also be executed from individual schemas by minor changes. If you need to exclude indxes of some other users that can also be added/changed in cGetIdx cursor. To execute this code from any schema other than SYS. Execute on DBMS_SQL must be granted from SYS(not system) to the the specified user.
Indexes with height less than three (3) should not be rebuilded. If you want to go for indexes with less heights that can also be customized by changing the height parameter.
Set serveroutput on size 100000
DECLARE
vOwner dba_indexes.owner%TYPE; /* Index Owner */
vIdxName dba_indexes.index_name%TYPE; /* Index Name */
vAnalyze VARCHAR2(100); /* String of Analyze Stmt */
vCursor NUMBER; /* DBMS_SQL cursor */
vNumRows INTEGER; /* DBMS_SQL return rows */
vHeight index_stats.height%TYPE; /* Height of index tree */
vLfRows index_stats.lf_rows%TYPE; /* Index Leaf Rows */
vDLfRows index_stats.del_lf_rows%TYPE; /* Deleted Leaf Rows */
vDLfPerc NUMBER; /* Del lf Percentage */
vMaxHeight NUMBER; /* Max tree height */
vMaxDel NUMBER; /* Max del lf percentage */
CURSOR cGetIdx IS SELECT owner,index_name
FROM dba_indexes WHERE OWNER NOT LIKE 'SYS%';
BEGIN
/* Define maximums. This section can be customized. */
vMaxHeight := 3;
vMaxDel := 20;
/* For every index, validate structure */
OPEN cGetIdx;
LOOP
FETCH cGetIdx INTO vOwner,vIdxName;
EXIT WHEN cGetIdx%NOTFOUND;
/* Open DBMS_SQL cursor */
vCursor := DBMS_SQL.OPEN_CURSOR;
/* Set up dynamic string to validate structure */
vAnalyze := 'ANALYZE INDEX ' || vOwner || '.' || vIdxName || ' VALIDATE STRUCTURE';
DBMS_SQL.PARSE(vCursor,vAnalyze,DBMS_SQL.V7);
vNumRows := DBMS_SQL.EXECUTE(vCursor);
/* Close DBMS_SQL cursor */
DBMS_SQL.CLOSE_CURSOR(vCursor);
/* Does index need rebuilding? */
/* If so, then generate command */
SELECT height,lf_rows,del_lf_rows INTO vHeight,vLfRows,vDLfRows
FROM INDEX_STATS;
IF vDLfRows = 0 THEN /* handle case where div by zero */
vDLfPerc := 0;
ELSE
vDLfPerc := (vDLfRows / vLfRows) * 100;
END IF;
IF (vHeight > vMaxHeight) OR (vDLfPerc > vMaxDel) THEN
DBMS_OUTPUT.PUT_LINE('ALTER INDEX ' || vOwner || '.' || vIdxName || ' REBUILD;');
END IF;
END LOOP;
CLOSE cGetIdx;
END;
* The percentage of deleted rows exceeds 30% of the total, i.e. if
del_lf_rows / lf_rows > 0.3.
* If the ‘HEIGHT’ is greater than 4.
* If the number of rows in the index (‘LF_ROWS’) is significantly smaller than ‘LF_BLKS’ this can indicate a large number of deletes, indicating that the index should be rebuilt.
Fast Index Rebuild.
The REBUILD option of the ALTER INDEX statement is executed to quickly rebuild an index using the existing index instead of the table:
alter index emp_idx1 rebuild parallel
tablespace user_tblspc1
storage (pctincrease 0);
Index altered.
Any Modifications to the STORAGE clause can be made at this time and the parallel option can also be used if parallelism is enabled in your database.
Using the REBUILD option of the ALTER INDEX statement for quickly rebuilding an index requires the existing index instead of the table. So necessary space should be available to store both the indexes during the REBUILD operation.
You can also REBUILD online clause to allow DML operations on the table. Index Rebuild online is not applicable for Bitmap indexes or for indexes that enfore referential Integirity Constraints.
This code genenates a script to rebuld all the indexes with height greater than 3 for all the users except for SYS user. The script needs to be executed from SYS schema. This can also be executed from individual schemas by minor changes. If you need to exclude indxes of some other users that can also be added/changed in cGetIdx cursor. To execute this code from any schema other than SYS. Execute on DBMS_SQL must be granted from SYS(not system) to the the specified user.
Indexes with height less than three (3) should not be rebuilded. If you want to go for indexes with less heights that can also be customized by changing the height parameter.
Set serveroutput on size 100000
DECLARE
vOwner dba_indexes.owner%TYPE; /* Index Owner */
vIdxName dba_indexes.index_name%TYPE; /* Index Name */
vAnalyze VARCHAR2(100); /* String of Analyze Stmt */
vCursor NUMBER; /* DBMS_SQL cursor */
vNumRows INTEGER; /* DBMS_SQL return rows */
vHeight index_stats.height%TYPE; /* Height of index tree */
vLfRows index_stats.lf_rows%TYPE; /* Index Leaf Rows */
vDLfRows index_stats.del_lf_rows%TYPE; /* Deleted Leaf Rows */
vDLfPerc NUMBER; /* Del lf Percentage */
vMaxHeight NUMBER; /* Max tree height */
vMaxDel NUMBER; /* Max del lf percentage */
CURSOR cGetIdx IS SELECT owner,index_name
FROM dba_indexes WHERE OWNER NOT LIKE 'SYS%';
BEGIN
/* Define maximums. This section can be customized. */
vMaxHeight := 3;
vMaxDel := 20;
/* For every index, validate structure */
OPEN cGetIdx;
LOOP
FETCH cGetIdx INTO vOwner,vIdxName;
EXIT WHEN cGetIdx%NOTFOUND;
/* Open DBMS_SQL cursor */
vCursor := DBMS_SQL.OPEN_CURSOR;
/* Set up dynamic string to validate structure */
vAnalyze := 'ANALYZE INDEX ' || vOwner || '.' || vIdxName || ' VALIDATE STRUCTURE';
DBMS_SQL.PARSE(vCursor,vAnalyze,DBMS_SQL.V7);
vNumRows := DBMS_SQL.EXECUTE(vCursor);
/* Close DBMS_SQL cursor */
DBMS_SQL.CLOSE_CURSOR(vCursor);
/* Does index need rebuilding? */
/* If so, then generate command */
SELECT height,lf_rows,del_lf_rows INTO vHeight,vLfRows,vDLfRows
FROM INDEX_STATS;
IF vDLfRows = 0 THEN /* handle case where div by zero */
vDLfPerc := 0;
ELSE
vDLfPerc := (vDLfRows / vLfRows) * 100;
END IF;
IF (vHeight > vMaxHeight) OR (vDLfPerc > vMaxDel) THEN
DBMS_OUTPUT.PUT_LINE('ALTER INDEX ' || vOwner || '.' || vIdxName || ' REBUILD;');
END IF;
END LOOP;
CLOSE cGetIdx;
END;
Automatic index rebuild and reorganizing
----------------------------------------------------
-- Automatic index rebuild and reorganizing
--
-- Reorganizes indexes with fragmentation between 10 and 30%
-- Rebuilds indexes with more than 30% fragmentation
--
-- Written by perb@episerver
----------------------------------------------------
declare @sql nvarchar(1000)
declare @indexname nvarchar(255)
declare @tablename nvarchar(255)
declare @fragmentation float
declare @msg nvarchar(512)
declare @dbid int
declare @indexCount int
set nocount on
set @dbid=db_id()
set @indexCount = 0
declare c CURSOR FOR
Select 'ALTER INDEX ' + i.name + ' ON ' + object_name(d.object_id) + CASE WHEN avg_fragmentation_in_percent>30 THEN ' REBUILD' ELSE ' REORGANIZE' END as [sql],
convert(decimal(5,2), avg_fragmentation_in_percent) fragmentation,object_name(d.object_id),i.name
from sys.dm_db_index_physical_stats( @dbid,null, -1, null, 'SAMPLED') d -- or 'DETAILED'
inner join sys.indexes i on i.object_id=d.object_id and i.index_id=d.index_id
where d.avg_fragmentation_in_percent > 10
order by avg_fragmentation_in_percent desc
select N'See "Messages" tab for progress!' as Info
raiserror (N'Reading index fragmentation..',0,1) WITH NOWAIT
raiserror (N' ',0,1) WITH NOWAIT
open c
fetch next from c INTO @sql,@fragmentation,@tablename,@indexname
while @@FETCH_STATUS = 0
begin
SET @msg = N'Found fragmented index..'
raiserror (@msg,0,1) WITH NOWAIT
SET @msg = N' Name: ' + @indexname
raiserror (@msg,0,1) WITH NOWAIT
SET @msg = N' Table: ' + @tablename
raiserror (@msg,0,1) WITH NOWAIT
SET @msg = N' Fragmentation: ' + cast(@fragmentation as nvarchar) + '%s'
raiserror (@msg,0,1,'%') WITH NOWAIT
exec sp_executesql @sql
set @indexCount = @indexCount + 1
SET @msg = N' Defrag done!'
raiserror (@msg,0,1) WITH NOWAIT
SET @msg = N' '
raiserror (@msg,0,1) WITH NOWAIT
fetch next from c INTO @sql,@fragmentation,@tablename,@indexname
end
close c
deallocate c
SET @msg = N'--------------------------------'
raiserror (@msg,0,1) WITH NOWAIT
SET @msg = N'Found and defragged ' + cast(@indexCount as nvarchar) + N' index(es)'
raiserror (@msg,0,1) WITH NOWAIT
-- Automatic index rebuild and reorganizing
--
-- Reorganizes indexes with fragmentation between 10 and 30%
-- Rebuilds indexes with more than 30% fragmentation
--
-- Written by perb@episerver
----------------------------------------------------
declare @sql nvarchar(1000)
declare @indexname nvarchar(255)
declare @tablename nvarchar(255)
declare @fragmentation float
declare @msg nvarchar(512)
declare @dbid int
declare @indexCount int
set nocount on
set @dbid=db_id()
set @indexCount = 0
declare c CURSOR FOR
Select 'ALTER INDEX ' + i.name + ' ON ' + object_name(d.object_id) + CASE WHEN avg_fragmentation_in_percent>30 THEN ' REBUILD' ELSE ' REORGANIZE' END as [sql],
convert(decimal(5,2), avg_fragmentation_in_percent) fragmentation,object_name(d.object_id),i.name
from sys.dm_db_index_physical_stats( @dbid,null, -1, null, 'SAMPLED') d -- or 'DETAILED'
inner join sys.indexes i on i.object_id=d.object_id and i.index_id=d.index_id
where d.avg_fragmentation_in_percent > 10
order by avg_fragmentation_in_percent desc
select N'See "Messages" tab for progress!' as Info
raiserror (N'Reading index fragmentation..',0,1) WITH NOWAIT
raiserror (N' ',0,1) WITH NOWAIT
open c
fetch next from c INTO @sql,@fragmentation,@tablename,@indexname
while @@FETCH_STATUS = 0
begin
SET @msg = N'Found fragmented index..'
raiserror (@msg,0,1) WITH NOWAIT
SET @msg = N' Name: ' + @indexname
raiserror (@msg,0,1) WITH NOWAIT
SET @msg = N' Table: ' + @tablename
raiserror (@msg,0,1) WITH NOWAIT
SET @msg = N' Fragmentation: ' + cast(@fragmentation as nvarchar) + '%s'
raiserror (@msg,0,1,'%') WITH NOWAIT
exec sp_executesql @sql
set @indexCount = @indexCount + 1
SET @msg = N' Defrag done!'
raiserror (@msg,0,1) WITH NOWAIT
SET @msg = N' '
raiserror (@msg,0,1) WITH NOWAIT
fetch next from c INTO @sql,@fragmentation,@tablename,@indexname
end
close c
deallocate c
SET @msg = N'--------------------------------'
raiserror (@msg,0,1) WITH NOWAIT
SET @msg = N'Found and defragged ' + cast(@indexCount as nvarchar) + N' index(es)'
raiserror (@msg,0,1) WITH NOWAIT
Wednesday, December 31, 2008
Identify the blocking session
Identify the blocking session
Oracle provides a view, DBA_BLOCKERS, which lists the SIDs of all blocking sessions. But this view is often, in my experience, a good bit slower than simply querying V$LOCK, and it doesn't offer any information beyond the SIDs of any sessions that are blocking other sessions. The V$LOCK view is faster to query, makes it easy to identify the blocking session, and has a lot more information.
SQL> select * from v$lock ;
ADDR KADDR SID TY ID1 ID2 LMODE REQUEST CTIME BLOCK
-------- -------- ---------- -- ---------- ---------- ---------- ---------- ---------- ----------
AF9E2C4C AF9E2C60 479 TX 131078 16739 0 6 685 0
ADDF7EC8 ADDF7EE0 422 TM 88519 0 3 0 697 0
ADDF7F74 ADDF7F8C 479 TM 88519 0 3 0 685 0
ADEBEA20 ADEBEB3C 422 TX 131078 16739 6 0 697 1
.... .... ... ... .... .... .... .... .... ....
Note the BLOCK column. If a session holds a lock that's blocking another session, BLOCK=1. Further, you can tell which session is being blocked by comparing the values in ID1 and ID2. The blocked session will have the same values in ID1 and ID2 as the blocking session, and, since it is requesting a lock it's unable to get, it will have REQUEST > 0.
In the query above, we can see that SID 422 is blocking SID 479. SID 422 corresponds to Session 1 in our example, and SID 479 is our blocked Session 2.
To avoid having to stare at the table and cross-compare ID1's and ID2's, put this in a query:
SQL> select l1.sid, ' IS BLOCKING ', l2.sid
from v$lock l1, v$lock l2
where l1.block =1 and l2.request > 0
and l1.id1=l2.id1
and l1.id2=l2.id2
SQL> /
SID 'ISBLOCKING' SID
---------- ------------- ----------
422 IS BLOCKING 479
1 row selected.
Even better, if we throw a little v$session into the mix, the results are highly readable:
SQL> select s1.username || '@' || s1.machine
|| ' ( SID=' || s1.sid || ' ) is blocking '
|| s2.username || '@' || s2.machine || ' ( SID=' || s2.sid || ' ) ' AS blocking_status
from v$lock l1, v$session s1, v$lock l2, v$session s2
where s1.sid=l1.sid and s2.sid=l2.sid
and l1.BLOCK=1 and l2.request > 0
and l1.id1 = l2.id1
and l2.id2 = l2.id2 ;
BLOCKING_STATUS
----------------------------------------------------------------------------------------------------
BULKLOAD@yttrium ( SID=422 ) is blocking BULKLOAD@yttrium ( SID=479 )
1 row selected.
There's still more information in the v$lock table, but in order to read that information, we need to understand a bit more about lock types and the cryptically-named ID1 and ID2 columns.
Lock type and the ID1 / ID2 columns
In this case, we already know that the blocking lock is an exclusive DML lock, since we're the ones who issued the locking statement. But most of the time, you won't be so lucky. Fortunately, you can read this information from the v$lock table with little effort.
The first place to look is the TYPE column. There are dozens of lock types, but the vast majority are system types. System locks are normally only held for a very brief amount of time, and it's not generally helpful to try to tune your library cache, undo logs, etc. by looking in v$lock! (See the V$LOCK chapter in the Oracle Database Reference for a list of system lock types.)
There are only three types of user locks, TX, TM and UL. UL is a user-defined lock -- a lock defined with the DBMS_LOCK package. The TX lock is a row transaction lock; it's acquired once for every transaction that changes data, no matter how many objects you change in that transaction. The ID1 and ID2 columns point to the rollback segment and transaction table entries for that transaction.
The TM lock is a DML lock. It's acquired once for each object that's being changed. The ID1 column identifies the object being modified.
Lock Modes
You can see more information on TM and TX locks just by looking at the lock modes. The LMODE and REQUEST columns both use the same numbering for lock modes, in order of increasing exclusivity: from 0 for no lock, to 6 for exclusive lock. A session must obtain an exclusive TX lock in order to change data; LMODE will be 6. If it can't obtain an exclusive lock because some of the rows it wants to change are locked by another session, then it will request a TX in exclusive mode; LMODE will be 0 since it does not have the lock, and REQUEST will be 6. You can see this interaction in the rows we selected earlier from v$lock:
ADDR KADDR SID TY ID1 ID2 LMODE REQUEST CTIME BLOCK
-------- -------- ---------- -- ---------- ---------- ---------- ---------- ---------- ----------
AF9E2C4C AF9E2C60 479 TX 131078 16739 0 6 685 0
ADEBEA20 ADEBEB3C 422 TX 131078 16739 6 0 697 1
Note that ID1 and ID2 in Session 2, which is requesting the TX lock (LMODE=0, REQUEST=6), point back to the rollback and transaction entries for Session 1. That's what lets us determine the blocking session for Session 2.
You may also see TX locks in mode 4, Shared mode. If a block containing rows to be changed doesn't have any interested transaction list (ITL) entries left, then the session acquires a TX lock in mode 4 while waiting for an ITL entry. If you see contention for TX-4 locks on an object, you probably need to increase INITRANS for the object.
TM locks are generally requested and acquired in modes 3, aka Shared-Row Exclusive, and 6. DDL requires a TM Exclusive lock. (Note that CREATE TABLE doesn't require a TM lock -- it doesn't need to lock any objects, because the object in question doesn't exist yet!) DML requires a Shared-Row Exclusive lock. So, in the rows we selected earlier from v$lock, you can see from the TM locking levels that these are DML locks:
ADDR KADDR SID TY ID1 ID2 LMODE REQUEST CTIME BLOCK
-------- -------- ---------- -- ---------- ---------- ---------- ---------- ---------- ----------
ADDF7EC8 ADDF7EE0 422 TM 88519 0 3 0 697 0
ADDF7F74 ADDF7F8C 479 TM 88519 0 3 0 685 0
Identifying the locked object
Now that we know that each TM row points to a locked object, we can use ID1 to identify the object.
SQL> select object_name from dba_objects where object_id=88519 ;
OBJECT_NAME
--------------
TSTLOCK
Sometimes just knowing the object is enough information; but we can dig even deeper. We can identify not just the object, but the block and even the row in the block that Session 2 is waiting on.
Identifying the locked row
We can get this information from v$session by looking at the v$session entry for the blocked session:
SQL> select row_wait_obj#, row_wait_file#, row_wait_block#, row_wait_row#
2* from v$session where sid=479 ;
ROW_WAIT_OBJ# ROW_WAIT_FILE# ROW_WAIT_BLOCK# ROW_WAIT_ROW#
------------- -------------- --------------- -------------
88519 16 171309 0
This gives us the object ID, the relative file number, the block in the datafile, and the row in the block that the session is waiting on. If that list of data sounds familiar, it's because those are the four components of an extended ROWID. We can build the row's actual extended ROWID from these components using the DBMS_ROWID package. The ROWID_CREATE function takes these arguments and returns the ROWID:
SQL> select do.object_name,
2 row_wait_obj#, row_wait_file#, row_wait_block#, row_wait_row#,
3 dbms_rowid.rowid_create ( 1, ROW_WAIT_OBJ#, ROW_WAIT_FILE#, ROW_WAIT_BLOCK#, ROW_WAIT_ROW# )
4 from v$session s, dba_objects do
5 where sid=543
6 and s.ROW_WAIT_OBJ# = do.OBJECT_ID ;
OBJECT_NAME ROW_WAIT_OBJ# ROW_WAIT_FILE# ROW_WAIT_BLOCK# ROW_WAIT_ROW# DBMS_ROWID.ROWID_C
--------------- ------------- -------------- --------------- ------------- ------------------
TSTLOCK 88519 16 171309 0 AAAVnHAAQAAAp0tAAA
And, of course, this lets us inspect the row directly.
SQL> select * from tstlock where rowid='AAAVnHAAQAAAp0tAAA' ;
FOO BAR
--- ---
1 a
Conclusion
We've seen how to identify a blocking session, and how to inspect the very row that the waiting session is waiting for. And, I hope, learned a bit about v$lock in the process.
Oracle provides a view, DBA_BLOCKERS, which lists the SIDs of all blocking sessions. But this view is often, in my experience, a good bit slower than simply querying V$LOCK, and it doesn't offer any information beyond the SIDs of any sessions that are blocking other sessions. The V$LOCK view is faster to query, makes it easy to identify the blocking session, and has a lot more information.
SQL> select * from v$lock ;
ADDR KADDR SID TY ID1 ID2 LMODE REQUEST CTIME BLOCK
-------- -------- ---------- -- ---------- ---------- ---------- ---------- ---------- ----------
AF9E2C4C AF9E2C60 479 TX 131078 16739 0 6 685 0
ADDF7EC8 ADDF7EE0 422 TM 88519 0 3 0 697 0
ADDF7F74 ADDF7F8C 479 TM 88519 0 3 0 685 0
ADEBEA20 ADEBEB3C 422 TX 131078 16739 6 0 697 1
.... .... ... ... .... .... .... .... .... ....
Note the BLOCK column. If a session holds a lock that's blocking another session, BLOCK=1. Further, you can tell which session is being blocked by comparing the values in ID1 and ID2. The blocked session will have the same values in ID1 and ID2 as the blocking session, and, since it is requesting a lock it's unable to get, it will have REQUEST > 0.
In the query above, we can see that SID 422 is blocking SID 479. SID 422 corresponds to Session 1 in our example, and SID 479 is our blocked Session 2.
To avoid having to stare at the table and cross-compare ID1's and ID2's, put this in a query:
SQL> select l1.sid, ' IS BLOCKING ', l2.sid
from v$lock l1, v$lock l2
where l1.block =1 and l2.request > 0
and l1.id1=l2.id1
and l1.id2=l2.id2
SQL> /
SID 'ISBLOCKING' SID
---------- ------------- ----------
422 IS BLOCKING 479
1 row selected.
Even better, if we throw a little v$session into the mix, the results are highly readable:
SQL> select s1.username || '@' || s1.machine
|| ' ( SID=' || s1.sid || ' ) is blocking '
|| s2.username || '@' || s2.machine || ' ( SID=' || s2.sid || ' ) ' AS blocking_status
from v$lock l1, v$session s1, v$lock l2, v$session s2
where s1.sid=l1.sid and s2.sid=l2.sid
and l1.BLOCK=1 and l2.request > 0
and l1.id1 = l2.id1
and l2.id2 = l2.id2 ;
BLOCKING_STATUS
----------------------------------------------------------------------------------------------------
BULKLOAD@yttrium ( SID=422 ) is blocking BULKLOAD@yttrium ( SID=479 )
1 row selected.
There's still more information in the v$lock table, but in order to read that information, we need to understand a bit more about lock types and the cryptically-named ID1 and ID2 columns.
Lock type and the ID1 / ID2 columns
In this case, we already know that the blocking lock is an exclusive DML lock, since we're the ones who issued the locking statement. But most of the time, you won't be so lucky. Fortunately, you can read this information from the v$lock table with little effort.
The first place to look is the TYPE column. There are dozens of lock types, but the vast majority are system types. System locks are normally only held for a very brief amount of time, and it's not generally helpful to try to tune your library cache, undo logs, etc. by looking in v$lock! (See the V$LOCK chapter in the Oracle Database Reference for a list of system lock types.)
There are only three types of user locks, TX, TM and UL. UL is a user-defined lock -- a lock defined with the DBMS_LOCK package. The TX lock is a row transaction lock; it's acquired once for every transaction that changes data, no matter how many objects you change in that transaction. The ID1 and ID2 columns point to the rollback segment and transaction table entries for that transaction.
The TM lock is a DML lock. It's acquired once for each object that's being changed. The ID1 column identifies the object being modified.
Lock Modes
You can see more information on TM and TX locks just by looking at the lock modes. The LMODE and REQUEST columns both use the same numbering for lock modes, in order of increasing exclusivity: from 0 for no lock, to 6 for exclusive lock. A session must obtain an exclusive TX lock in order to change data; LMODE will be 6. If it can't obtain an exclusive lock because some of the rows it wants to change are locked by another session, then it will request a TX in exclusive mode; LMODE will be 0 since it does not have the lock, and REQUEST will be 6. You can see this interaction in the rows we selected earlier from v$lock:
ADDR KADDR SID TY ID1 ID2 LMODE REQUEST CTIME BLOCK
-------- -------- ---------- -- ---------- ---------- ---------- ---------- ---------- ----------
AF9E2C4C AF9E2C60 479 TX 131078 16739 0 6 685 0
ADEBEA20 ADEBEB3C 422 TX 131078 16739 6 0 697 1
Note that ID1 and ID2 in Session 2, which is requesting the TX lock (LMODE=0, REQUEST=6), point back to the rollback and transaction entries for Session 1. That's what lets us determine the blocking session for Session 2.
You may also see TX locks in mode 4, Shared mode. If a block containing rows to be changed doesn't have any interested transaction list (ITL) entries left, then the session acquires a TX lock in mode 4 while waiting for an ITL entry. If you see contention for TX-4 locks on an object, you probably need to increase INITRANS for the object.
TM locks are generally requested and acquired in modes 3, aka Shared-Row Exclusive, and 6. DDL requires a TM Exclusive lock. (Note that CREATE TABLE doesn't require a TM lock -- it doesn't need to lock any objects, because the object in question doesn't exist yet!) DML requires a Shared-Row Exclusive lock. So, in the rows we selected earlier from v$lock, you can see from the TM locking levels that these are DML locks:
ADDR KADDR SID TY ID1 ID2 LMODE REQUEST CTIME BLOCK
-------- -------- ---------- -- ---------- ---------- ---------- ---------- ---------- ----------
ADDF7EC8 ADDF7EE0 422 TM 88519 0 3 0 697 0
ADDF7F74 ADDF7F8C 479 TM 88519 0 3 0 685 0
Identifying the locked object
Now that we know that each TM row points to a locked object, we can use ID1 to identify the object.
SQL> select object_name from dba_objects where object_id=88519 ;
OBJECT_NAME
--------------
TSTLOCK
Sometimes just knowing the object is enough information; but we can dig even deeper. We can identify not just the object, but the block and even the row in the block that Session 2 is waiting on.
Identifying the locked row
We can get this information from v$session by looking at the v$session entry for the blocked session:
SQL> select row_wait_obj#, row_wait_file#, row_wait_block#, row_wait_row#
2* from v$session where sid=479 ;
ROW_WAIT_OBJ# ROW_WAIT_FILE# ROW_WAIT_BLOCK# ROW_WAIT_ROW#
------------- -------------- --------------- -------------
88519 16 171309 0
This gives us the object ID, the relative file number, the block in the datafile, and the row in the block that the session is waiting on. If that list of data sounds familiar, it's because those are the four components of an extended ROWID. We can build the row's actual extended ROWID from these components using the DBMS_ROWID package. The ROWID_CREATE function takes these arguments and returns the ROWID:
SQL> select do.object_name,
2 row_wait_obj#, row_wait_file#, row_wait_block#, row_wait_row#,
3 dbms_rowid.rowid_create ( 1, ROW_WAIT_OBJ#, ROW_WAIT_FILE#, ROW_WAIT_BLOCK#, ROW_WAIT_ROW# )
4 from v$session s, dba_objects do
5 where sid=543
6 and s.ROW_WAIT_OBJ# = do.OBJECT_ID ;
OBJECT_NAME ROW_WAIT_OBJ# ROW_WAIT_FILE# ROW_WAIT_BLOCK# ROW_WAIT_ROW# DBMS_ROWID.ROWID_C
--------------- ------------- -------------- --------------- ------------- ------------------
TSTLOCK 88519 16 171309 0 AAAVnHAAQAAAp0tAAA
And, of course, this lets us inspect the row directly.
SQL> select * from tstlock where rowid='AAAVnHAAQAAAp0tAAA' ;
FOO BAR
--- ---
1 a
Conclusion
We've seen how to identify a blocking session, and how to inspect the very row that the waiting session is waiting for. And, I hope, learned a bit about v$lock in the process.
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