ps and top differences with HugePages

The Unix utilities ps and top report memory differently with HugePages than without.

Without HugePages ps seems to include the SGA memory under the SZ column:

oracle    1822     1  0 846155 16232  0 07:19 ?        00:00:00 ora_d000_orcl
oracle    1824     1  0 846155 16228  0 07:19 ?        00:00:00 ora_d001_orcl
oracle    1826     1  0 846155 16236  0 07:19 ?        00:00:00 ora_d002_orcl
oracle    1828     1  0 846155  (more...)

Virtual Circuit Wait

On Monday we had some performance problems on a system that includes a database which uses shared servers.  The top wait was “virtual circuit wait”.  Here are the top 5 events for a 52 minute time frame:

Top 5 Timed Foreground Events

Event Waits Time(s) Avg wait (ms) % DB time Wait Class
virtual circuit wait 1,388,199 17,917 13 50.98 Network
db file sequential read 1,186,933 9,252 8 26.33 User I/O

First AZORA usergroup meeting October 23

Just got the invitation to the first AZORA (Arizona Oracle user group) meeting on October 23.  Here is the link: url

It’s 2 pm at Oracle’s office, 2355 E Camelback Rd Ste 950, Phoenix, AZ.

I’m looking forward to it!

– Bobby

OS Watcher Paging Example

I have an example of paging in some Exadata OS Watcher log files.  We got an error in the alert log about a high load but reviewing AWR reports it did not seem like we had an unusual number of active sessions.  Also, the CPU use seemed low but the system load was high.  Reviewing the OS Watcher logs and finding a similar case on Oracle’s support site convinced me that our (more...)


Yesterday and today I’ve read or heard two people mention the force_match => TRUE parameter value for DBMS_SQLTUNE.IMPORT_SQL_PROFILE and how it forces a profile to work on all SQL statements that are the same except for their literal values.  So, I ran a quick test using the coe_xfr_sql_profile.sql utility that comes with the SQLT scripts that are available for download on Oracle’s support site.

I’ve mentioned in earlier posts how we use (more...)

Arizona Oracle User Group (AZORA)

I saw this fun blog post about the Arizona Oracle User Group getting organized: blog post

I’m definitely interested in being involved.  Please pass this on to any Oracle DBAs, developers, etc. that you know in the Phoenix area.

- Bobby

Commit Puzzle

This graph represents commit time compared to CPU utilization and redo log write time.  I’ve included only the hourly intervals with more than 1,000,000 commits.  At these peaks the number of commits ranges 1 to 1.6 million commits per hour so each point on the graph represents roughly the same commit rate.  I’m puzzled by why the commit time bounces around peaking above 5 milliseconds when I can’t see any peaks (more...)

Commit scalability

I am learning about how well commits scale on Oracle 11.2 and so far they seem to scale surprisingly well.

I’ve looked at two waits – log file parallel write and log file sync.  Based on documents I’ve read on Oracle’s support site log file parallel write represents the time it takes to do one write to the redo logs.  For mirrored redo logs the log file parallel write time includes the (more...)

Passed OCP 12c test

Well, I finally passed the Oracle Certified Professional (OCP) 12c upgrade exam, 1Z0-060.  I got 86% right on the new features section and 78% correct on the general DBA section.  So, that means I missed roughly 7 questions on each section which was more than I expected because I felt good about all of my answers.

I’m happy with the three resources I used which are:

  1. Self Test software – $99
  2. Matthew Morris (more...)

Query with new plan

I came up with a simple query that shows a running SQL executing a different plan than what it had in the past.  Here is the query:

-- show currently executing sqls that have history
-- but who have never run with the current plan
-- joins v$session to v$sql to get plan_hash_value of 
-- executing sql.
-- queries dba_hist_sqlstat for previously used values 
-- of plan_hash_value.
-- only reports queries that have an  (more...)