Technology Errors

PostgreSQL Table Issue: Mduplicate key value violates unique constraint

ErrorsLeave a comment

It is possible for data within a PostgreSQL database table to get out of sync. When this happens it is possible for an attempt to be made to write data to a row in a table that already exists. This is being kept track of internally within Postgres by an ID of some sort and you can reset what the next ID that will be written to a row will be. Typically this will resolve your issue.

I received the below error in a Ruby on Rails application that was attempting to write data to PostgreSQL and at some point the data got out of wack.

Technology Insights

Cacti Graph Templates Explained: RRDTool Graphing Solution

InsightsLeave a comment
**Please Note This Article Is Paginated at the bottom and includes 4 pages**

How do I create Cacti Graph Templates? How do I display multiple data sources on one Cacti graph? What do all the Cacti options mean? What is a CDEF? I created a Cacti Graph but all of my data sources are displaying NAN, how do I troubleshoot that?

Cacti is a powerful RRDTool based graphing system typically used for graphing hardware and software data for historical reference. When I initially configured a Cacti Graph Template I found some of the options confusing but as you will see below they all make sense and typically the name explains each items function in a fairly easy way. Please post a comment if you have any further questions that are not answered or if I have made any answers feel free to use the contact form and point them out to me as I am trying to learn the best way to use Cacti just like everyone else. I repeat the same terms many times in this document simply for the fact to try and explain in detail what things mean. I did not want to start switching names with acronyms and vice verse to add confusion and to try and make this a very easy document to understand.