Non-local RAC parallel executions of the select part?
Tell us more about the partitioning, and whether partitions are being
dynamically added or increased in size during the insert.
Tell us whether previous deletions have made long convoluted insert eligible
contestant freespace bit maps or freelists/freelist groups.
If there is a reasonable way to partition the select into chunks exactly
corresponding to the range partition destinations, it is likely you can run 4
(say) copies of the insert each inserting into the requisite destination
partition by name and each at parallel 1, and if this is 4 node rac, each using
a different insert node.
Or it could be something completely different.
mwf
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On ;
Behalf Of Petr Novak ("novak_petr")
Sent: Wednesday, April 10, 2024 8:35 AM
To: Oracle List
Subject: Increased runtime and 4 xids for one insert
Hallo,
there is problem with increasing execution time of simple Insert statement.
(insert into T_TARGET select * from T_SOURCE)
Execution time increased overproportionally to increased number of rows.
11 millions rows took 3,5 hours , 38 million rows 3 days.
T_TARGET is 1,5 TB range partitioned table , 1469 partitions and 5 local
indexes (same partitioned key as the table).
for shorter execution time there was one XID, but for long execution time 4
XIDs ??
select xid, SQL_EXEC_START,SESSION_ID,SESSION_SERIAL#,count(*)
,to_char(min(sample_time),'dd.mm hh24:mi:ss') mint,
to_char(max(sample_time),'dd.mm hh24:mi:ss') maxt
from dba_hist_active_sess_history where sql_id='fdq9c3q9jfavc'
and sample_time>to_date('2404052000','yymmddhh24mi') and sample_time<
to_date('2404082100','yymmddhh24mi')
group by xid,SQL_EXEC_START,SESSION_ID,SESSION_SERIAL# order by
SQL_EXEC_START,min(sample_time);
XID SQL_EXEC_START SESSION_ID SESSION_SERIAL#
COUNT(*) Min(IntervalEnd) Max(IntervalEnd)
---------------- ------------------- -------------- ---------------
-------------- -------------------- --------------------
05.04.2024 20:13:40 1141 11657
8 05.04 20:13:44 05.04 20:14:15
2E00180051D62200 05.04.2024 20:13:40 1141 11657
12532 05.04 20:14:25 06.04 14:04:03
05.04.2024 20:13:40 1064 35873
12 05.04 20:39:31 06.04 01:42:10
05.04.2024 20:13:40 1016 54350
8 05.04 20:49:35 05.04 22:16:08
05.04.2024 20:13:40 1103 5986
16 05.04 21:00:10 06.04 02:49:36
05.04.2024 20:13:40 986 61332
6 05.04 21:34:39 06.04 04:26:03
20001C0008633B00 06.04.2024 14:04:10 1141 11657
24486 06.04 14:04:13 08.04 00:55:20
06.04.2024 14:04:10 1057 63794
6 06.04 14:08:29 07.04 01:10:29
06.04.2024 14:04:10 1026 41466
8 06.04 14:21:17 06.04 23:58:37
06.04.2024 14:04:10 1103 51053
16 06.04 14:36:49 06.04 22:38:23
15001100CD95C100 08.04.2024 00:55:22 1141 11657
8986 08.04 00:55:31 08.04 13:42:29
08.04.2024 00:55:22 1026 1396
8 08.04 00:59:06 08.04 03:59:52
08.04.2024 00:55:22 1104 28322
8 08.04 01:05:14 08.04 02:51:25
08.04.2024 00:55:22 1005 29042
8 08.04 01:21:07 08.04 03:53:02
08.04.2024 00:55:22 1075 54721
4 08.04 02:05:30 08.04 02:20:00
03001200F4F1B600 08.04.2024 13:42:30 1141 11657
4178 08.04 13:42:39 08.04 19:39:05
08.04.2024 13:42:30 325 35023
10 08.04 13:48:48 08.04 16:16:38
08.04.2024 13:42:30 296 7915
2 08.04 14:30:27 08.04 14:30:27
08.04.2024 13:42:30 369 46540
4 08.04 14:55:12 08.04 16:05:22
08.04.2024 13:42:30 395 14967
8 08.04 15:38:13 08.04 18:20:44
03001200F4F1B600 1141 11657
16 08.04 19:39:15 08.04 19:40:27
In dba_hist_undostat are same 4 execution start times for this query
(maxquerylen,maxquerysqlid).
During the execution I checked the transaction_start and last_call_et in the
session 1141 and it loooked like TX started hours later since
last_call_et. TX start was one of these SQL_EXEC_STARTs
In dba_hist_sqlstat only one execution is shown, most time was spend with CPU.
most ASH samples are related to UNDO TS.
select tablespace_name,count(*)
from dba_hist_active_sess_history ,dba_data_files where sql_id='fdq9c3q9jfavc'
and CURRENT_FILE#=file_id
and sample_time>to_date('2404052000','yymmddhh24mi') and sample_time<
to_date('2404082100','yymmddhh24mi')
group by tablespace_name order by count(*) desc;
TABLESPACE_NAME COUNT(*)
------------------------------ --------------
UNDOTBS1 32746
RB_STAGING_TAB 17576
There are also some intervals with increased commit times (2->100ms) , but for
me it looks like another issue.
I have two main questions :
- how it is possible to have for one execution 4 XIDs ?
- where the statements spends the time ?
Any ideas ?
Best Regards,
Petr
