Recently I took over a HPUX running oracle 10g, when checking the alert log, I saw a few ORA-27300, ORA-27301, ORA-27301 errors, /var/log/messages also shows this:
Deferred swap reservation failure pid: 12345.
Apparently system doesn't have enough swap space for oracle.
$ swapinfo -am
Mb Mb Mb PCT START/ Mb
TYPE AVAIL USED FREE USED LIMIT RESERVE PRI NAME
dev 6656 195 6461 3% 0 - 1 /dev/vg00/lvol2
reserve - 3134 -3134
memory 4536 1109 3427 24%
swapinfo shows that system has 4.5G physical memory, swap space is 6.6G, a bit smaller but quite close to oracle recommanded 4.5X1.5G
further check found that system hit ORA-27300 daily between 18:00 and 20:00, there must be some job running during this period causing the excessive swap usage.
AWR report shows this sql suspicous:
SELECT table_a.column_1, table_a.column_2, table_a.column_3
BULK COLLECT INTO
col_1, col_2, col_3
FROM table_a, table_b, table_c
WHERE table_a.created_date >= to_date(:1,'dd/mm/yyyy:hh24:mi')
AND table_a.created_date <= to_date(:2,'dd/mm/yyyy:hh24:mi');
two issues with this sql:
1. cartition join table_b table_c, yet no columns from table_b and table_c are selected columns
the cartition join of table_b and table_c produces about 2 billion rows,
so if there is 1 row in table_a match the WHERE condition, sql will try to load the same row 2 billion times in memory.
2. use BULK COLLECT INTO directly
according to oracle, BULK COLLECT should always be used with LIMIT
It turns out that the sql is part of a procedure, which runs daily at 18:00.
Since the job has been failing for months, I just disabled it, informed development team to rectify it.
So far two weeks passed, both server and database are working fine, no more ORA-27300 or "Deferred swap reservation failure" appears.
reference:
http://www.oracle-base.com/articles/9i/bulk-binds-and-record-processing-9i.php
http://www.oracle.com/technetwork/issue-archive/2008/08-mar/o28plsql-095155.html
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