Archive for the 'Uncategorized' Category

The future is clear….

Mt. Hood

The journey to the cloud is pretty obvious these days.   I have been playing with various pieces over the last few years and Oracle’s direction is pretty clear.  I will be posting bits and pieces of my journey into the cloud as things become more clear.

“external table write” wait events… but I am only running a query?

I was helping a customer debug some external table load problems.  They are developing some code to do massive inserts via external tables.  As the code was being tested, we saw a fair number of tests that were doing simple queries of an external table.  I expected to see “external table read” wait events, but was surprised when we saw more “external table write” wait events than reads.

I thought this was due to writes to the “log” file and possible “bad” file, but I had to be sure.  I searched the docs but could not find reference to this wait event.  I specifically was seeing the following:

WAIT #139931007587096: nam='external table write' ela= 7 filectx=139931005791096 file#=13 size=41 obj#=-1 tim=1398264093597968
WAIT #139931007587096: nam='external table write' ela= 3 filectx=139931005791096 file#=13 size=89 obj#=-1 tim=1398264093597987

I searched on how to debug the filectx and file# but still couldn’t find anything.  So, I resorted to my good old friend “strace” from the Linux side of the house.  By running “strace” on the oracle shadow process, I was able to find indeed that these write events were to going to the LOG file for the external table.

mylap:EXTW glennf$ egrep 'write\(13' strace-truss-trace.txt
 write(13, "\n\n LOG file opened at 04/23/14 0"..., 41) = 41
 write(13, "KUP-05004: Warning: Intra sour"..., 100) = 100
 write(13, "Field Definitions for table ET_T"..., 36) = 36
 write(13, " Record format DELIMITED, delim"..., 43) = 43
 write(13, " Data in file has same endianne"..., 51) = 51
 write(13, " Rows with all null fields are "..., 41) = 41
 write(13, "\n", 1) = 1
 write(13, " Fields in Data Source: \n", 26) = 26
 write(13, "\n", 1) = 1
 write(13, " ID "..., 47) = 47
 write(13, " Terminated by \"7C\"\n", 25) = 25
 write(13, " Trim whitespace same as SQ"..., 41) = 41
 write(13, " TDATE "..., 46) = 46
  ....
  ....

Each time you open an external table, the time is logged as well the table definition.  We have some very wide tables so there was actually more data logged than queried.  With the proper amount of data now in the dat files, we are indeed seeing more “external table read” requests as expected.   Regardless, this was a fun exercise.

So, the moral of the story… Sometimes you have turn over a few rocks and drill down a bit to find the pot of gold.

 

MAA tests on Exadata… demystifying availability tests

MAA tests on Exadata… demystifying availability tests

I have not had a lot of time to post recently due to various reasons and a switch in jobs at Oracle.  I currently am 100% dedicated to working in the Oracle Solution Center to help customers test the performance on Oracle’s engineered solutions.  So, why am I sending this link?

Regardless of the performance tests that are performed, I often spend a fair amount of time showing the Availability aspects as well.  Hopefully this video will help to demystify the availability aspects of Exadata.

Glenn Fawcett’s transplanted blog… Discussing Oracle database performance with Sun servers

With the acquisition of Sun quickly approaching, I decided it was time to get a personal blog to discuss Oracle performance on Sun. I have maintained a blog at Sun for the past 3 years, so I am not new to the powers of blogging.  I want to continue to post material during the transition and not have to come up to speed on another blogging platform and the required logistics.  Blogging helps me discuss current trends regarding database performance in real-time as well as preview and refine material that eventually becomes a presentation or white paper.

Why did I choose WordPress?

The are multiple reasons.  The functionality is one of the best in the business.  The interface is smooth and intuitive which allows you quickly express yourself.  Also, for the past 5 months I have been working closely with an old friend Kevin Closson on Exadata V2 performance.  Kevin is  an avid blogger on WordPress as well… So all-in-all, WordPress seemed a natural fit.

take care,
Glenn