Take the 2-minute tour ×
Database Administrators Stack Exchange is a question and answer site for database professionals who wish to improve their database skills and learn from others in the community. It's 100% free, no registration required.

We created an image of one of our database servers in Rackspace. Then, we created a new server using that image, expecting things to work. However, the index performance we have seen seems to be bad, and even the query plans, when comparing the explain analyze outputs from the first server to the second one, have been different. Basically, the second server - the one that was restored from a saved image - does not seem to rely on indexes as it should.

Is there something related to image restore that would cause this behavior? If so, what may need to be done to fix the issue? Should I look somewhere else?

Thanks very much! I can provide more information if needed, so let me know if that would be useful.

share|improve this question
    
Did you run (vacuum) analyze on the new server? –  a_horse_with_no_name Mar 15 '13 at 20:18
    
Yes, we did. We also set enable_seqscan = off and it didn't use the indexes. It used the indexes temporarily and then reverted to not using them. –  Juan Carlos Coto Mar 15 '13 at 20:44
add comment

1 Answer

up vote 2 down vote accepted

I work for Rackspace and would like to help. Can you please post some details on exactly how the image was created? Are these both listed in your control panel as "next-gen servers" or is one "first-gen"? Differences here may explain some of the performance discrepancies you're experiencing.

It would be extremely helpful if you could provide query plans from both servers (http://www.postgresql.org/docs/current/static/performance-tips.html#using-explain).

A tool like explain.depesz (http://explain.depesz.com/help) may also help you to identify whether the queries are performing the same way on both machines.  

Feel free to post your answers here for the community to help (if you are comfortable) - or drop me a line at shaggy@rackspace.com with details and I'll be happy to coordinate with your support team.

share|improve this answer
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.