USER I/O Wait (Please help kind of stuck here from long time)

Question

I have a delete statement running from more than 24 hrs now and the session info says its waiting on user I/O. There are no blocking sessions and its doing a full table scan of a table having around 500000 records. I dont understand what exactly its waiting on and how to check that and why it taking more than 24 hrs to FTS of 1 table? Here are some of the statistics:
SQL> select blocking_session, event, wait_class, wait_time, seconds_in_wait, state from v$session where sid=1026;
BLOCKING_SESSION EVENT WAIT_CLASS WAIT_TIME SECONDS_IN_WAIT
STATE
db file scattered read User I/O 0 0
WAITING
SQL> select * from table(dbms_xplan.display_cursor('1g5k0k3qpy8j2'));
PLAN_TABLE_OUTPUT
SQL_ID 1g5k0k3qpy8j2, child number 0
DELETE FROM RX_TX WHERE ID IN (SELECT ID FROM TEMP_PURGE WHERE TABLE_NAME = 'rx_
tx')
Plan hash value: 3126475949
PLAN_TABLE_OUTPUT
| Id | Operation | Name | Rows | Bytes |TempSpc| Cost (%CPU)
| Time |
| 0 | DELETE STATEMENT | | | | | 17239 (100)
| |
| 1 | DELETE | RX_TX | | | |
| |
PLAN_TABLE_OUTPUT
|* 2 | HASH JOIN RIGHT SEMI| | 513K| 123M| 14M| 17239 (2)
| 00:03:27 |
|* 3 | TABLE ACCESS FULL | TEMP_PURGE | 557K| 8717K| | 2789 (2)
| 00:00:34 |
| 4 | TABLE ACCESS FULL | RX_TX | 578K| 130M| | 6918 (2)
| 00:01:24 |
PLAN_TABLE_OUTPUT
Predicate Information (identified by operation id):
2 - access("ID"="ID")
3 - filter("TABLE_NAME"='rx_tx')
22 rows selected.
SQL> select b.name, a.value from v$sesstat a, v$statname b
where a.statistic# = b.statistic#
and a.value > 0 2 3
4 and b.name like '%wait%'
5 and a.sid=1026;
NAME VALUE
concurrency wait time 1615
application wait time 388
user I/O wait time 13403000
enqueue waits 1
shared hash latch upgrades - no wait 7924935
redo log space wait time 2852
6 rows selected.
Any help would be appreciable.
This deletes more that 60% of the records from this table so indexed should be out of question here, i think.
Daljit Singh
Message was edited by:
Daljit

Answer 1

Thanks for replying Reega, here is the required
info:
SQL> select p1text, p1, p2text, p2, p3text, p3 from
v$session where sid=1026;
P1TEXT
1
P2TEXT
2
P3TEXT
3
file#
block#
16937
blocks
6
Actually Reega had a good point, not sure why he didn't go down the route.
You may want to find out what's that table/index your session is waiting from the value, something like
select   owner||'.'||segment_name,  segment_type
from dba_extents
where file_id=4 and (block_id between 116937 and 116937+66)This might be a long run query if you have many objects.
Actually the better view to query is v$session_wait instead of v$session.
Check article you might find useful,
Oracle wait tuning with v$session_wait