Author Archives: Bobby

About Bobby

I live in Chandler, Arizona with my wife and three daughters. I work for US Foods, the second largest food distribution company in the United States. I have worked in the Information Technology field since 1989. I have a passion for Oracle database performance tuning because I enjoy challenging technical problems that require an understanding of computer science. I enjoy communicating with people about my work.

SQR with 077 umask creates file with 611 permissions

I ran across this strange situation. An SQR opened a new data file for output and created the file with 611 permissions. We needed group read access so this caused a problem. I knew that our login script for the … Continue reading

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Unrolling loop speeds up program

This is a follow-up to my earlier post about the assembly language book that I am working through. I have struggled to speed up a program using something that the book recommends, unrolling a loop. I think I have finally … Continue reading

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Modified PythonDBAGraphs to use datetime on X axis

I modified PythonDBAGraphs to use datetime objects on the X axis for all the reports except ashcpu.py. This lets you hover the mouse over a point and see the date and time for the point. Previously I was using text … Continue reading

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Pushed out new version of PythonDBAGraphs

I pushed out a new version of PythonDBAGraphs. I got a new laptop at work so I am setting it up with the software that I need to do my job. I decided that instead of reinstalling Enthought Canopy I would go … Continue reading

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X86-64 Assembly Book

I have written earlier blog posts about my diversion from studying Oracle to studying computer science. Here are some relevant posts: url1,url2,url3,url4. After finishing the math for computer science online class and book that I was working on I stared working … Continue reading

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Finished reading the Snowflake database documentation

I just finished reading the Snowflake database documentation and I thought I would blog about my impressions. I have not spent a lot of time using Snowflake so I can not draw from experience with the product. But, I read all … Continue reading

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Submitted two abstracts for Oracle OpenWorld 2017

I submitted two abstracts for Oracle OpenWorld 2017. I have two talks that I have thought of putting together: Python for the Oracle DBA Toastmasters for the Oracle DBA I want to do these talks because they describe two things that I … Continue reading

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How to find the object that caused ORA-08103 error

A developer told me that two package executions died with ORA-08103 errors and he didn’t know which object caused the errors. I found two trace files that had the following contents: *** SESSION ID:(865.1201) 2017-04-17 10:17:09.476 OBJD MISMATCH typ=6, seg.obj=21058339, diskobj=21058934, … Continue reading

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Optimizer bug fix makes a query run more than 3 times slower

I’m working on an 11.1.0.7 to 11.2.0.4 upgrade and found a handful of queries that run more than 3 times longer on 11.2.0.4 than 11.1.0.7. The data and optimizer statistics are very similar on the two test databases. I’m pretty … Continue reading

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_small_table_threshold=1000000 results in > 5x query speedup

Today I sped a query up by over 5 times by setting _small_table_threshold=1000000. Here is the query elapsed time and a piece of the plan showing its behavior before setting the parameter: Elapsed: 00:28:41.67 —————————————————————————————————————————————————————————- | Id | Operation | Name … Continue reading

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