IP CIDR rules and address ranges

I always forget IP address range coverage rules and forget where to look.

It’s the wiki!

and for good reference here is the table:

https://en.wikipedia.org/wiki/Classless_Inter-Domain_Routing

 

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Best method for tuning sub-optimal execution plans

How do you determine if the Oracle SQL optimizer has created a sub-optimal execution plan? re-run statistics and see what happens? wait for Oracle to fin other execution plans? What if neither method is helping? Do you read the execution plan? What do you look at? Differences in actual vs estimated? How successful is that? Look for full table scans?  Do you look at the 10053 trace? How much time and effort does that take?  (more...)

Oaktable World 2017 @ Oracle Open World

 

http://www.oaktable.net/blog/oak-table-world-2017-oracle-open-world

The Oak Table members will be discussing their latest technical obsessions and research on Monday and Tuesday, (Oct. 2nd and 3rd, 2017).  The truth is, folks-  The Oak Table experts are an AWESOME group, (if I don’t say so myself! :)) as we could have easily done another day of incredible sessions, but alas, two days is all we have available for this year’s event.

 

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benchmarking your disks

 

While at Delphix, we did a lot of storage benchmarking. The I/O response times of Delphix depends, as one would logically imagine, heavily on the underlying disks. Sure Delphix can cache a lot ( with 1 TB of ram and 3x compression that’s 3TB and that 3TB can be shared by 10 or a 100 copies being the equivalent to 30TB or 300TB of databases) but really there will always be important I/O coming (more...)

Postgres monitoring script pgmon.sh

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photo by Thomas Hawk

https://github.com/khailey/pgmon

$ ./pgmon.sh 
Usage: pgmon.sh [username] [password] [host] <sid=postgres> <port=5432> <runtime=3600>

$ ./pgmon.sh kyle kyle  mymachine.com

  psql -t -h mymachine.com -p 5432 -U kyle postgres < /tmp/MONITOR/tmp/mymachine.com:postgres_collect.pipe &

  RUN_TIME=-1
  COLLECT_LIST=
  FAST_SAMPLE=wts
  TARGET=mymachine.com:postgres
  DEBUG=0

  Connected, starting collect at Wed Mar 8 12:05:12 PST 2017
  starting stats collecting
  SET

  AAS| blks_hit | blks_read | tup_returned | tup_fetched | tup_inserted | tup_updated | tup_deleted  

    (more...)

Example Jmeter workload for Postgres and Oracle

pgload.jmx is JMX file you can load into Jmeter and run a substantial load on a Postgres database. Should work just as well on Oracle if you change the test SQL from “Select 1″ to “select 1 from dual”

Install jmeter on our machine . On my mac, I did

  • brew install jmeter

You will need the Postgres driver. I used

9th Circuit Court Ruling 3-0

Little did I know this building that captured my visual attention and imagination so many times walking to work over the last 6 months would play a historic roll in the current political climate.

Here is a picture of the US District Court House from recent articles

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And here are some of my iPhone shots over the last few months with some Instagram filtering mixed in :)

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jmeter – Variable Name must not be null in JDBC Request

So Jmeter seems super cool.

I’ve only used it a little bit but it does seem a bit touchy about somethings (like spaces in input fields) and the errors are often less than obvious and I’m not finding that much out there on google for the errors.

Today I ran into the error

Variable Name must not be null in JDBC Request

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and Googling it didn’t turn up anything.

I’m pretty sure I ran (more...)

jmeter – getting started

This blog post is just a start at documenting some of my experiences with jmeter. As far as load testing tools go, jmeter looks the most promising to me. It has an active community, supports many different databases and looks quite flexible as far as architecting different work loads goes.

The flexibility of jmeter also makes it hard to use. One can use jmeter for many other things besides databases so the initial set up (more...)

Graphics for SQL Optimization

Dan Tow, in his book SQL Tuning, lays out a simple method of tuning SQL queries. The method is

  • Draw a diagram of each table in the query with Children above Parents
  • Draw join lines between each join (many-to-many, one-to-many)
  • Mark each table with a predicate filter and calculate the amount of table filtered out

Then to find a great optimal optimization path candidate

  1. Start at the table with the strongest predicate filter (the (more...)