EC2 Instance Performance

I’ve been working with a large-ish MySQL table on an EC2 instance. This table has approximately 147MM rows, and I’ve been disappointed with the performance I’ve seen. I took a look at how much performance I could gain by moving to a more powerful EC2 instance, and the answer is “some, but not all upgrades are equal”.

Problem/Test Case

This is the query I’m using as a test case:

Select b.respondent_name,
From (Select respondent_id,
             Sum(tr_tot_transaction_chrg) As tv
      From eqr_transaction
      Where report_yr = 2007
      And report_prd = 3
      Group By respondent_id) a
Join eqr_s0_respondent_id b
On b.respondent_id = a.respondent_id
Order By Desc
Limit 20

Some relevant details:

  • The Where clause uses an index to select ~8.3MM rows from the 147MM in the table
  • The Group By clause generates ~3000 result rows
  • The database is MySQL 5
  • The DB files are stored on an EBS device
  • All queries are run from the mysql command line client


I ran the query 3 times on each instance. Here is a summary of the results of those timing experiments.

VM information ET results
Instance Type Cost ($/hr) Run 1 Run 2 Run 3 Average
m1.small 0.10 180s 175s 177s 177s
m1.large 0.40 110s 77s 77s 88s
m1.xlarge 0.80 105s 76s 76s 86s
c1.medium 0.20 93s 70s 70s 78s
c1.xlarge 0.80 78s 47s 47s 57s


The c1.medium Instance Type is a decent upgrade: It offers roughly double the performance for double the price. For this problem, it appears strictly preferable to the m1.large and m1.xlarge Instance Types, and preferable on a “bang-for-the-buck” basis to the c1.xlarge Instance Type.

It is not clear why c1.medium outperformed m1.xlarge, since the latter completely outclasses the former on paper. I suspect either that my testing program was flawed (i.e. EC2 performance is extremely volatile) or that the 64-bit implementation of some piece of software is not all that it might be.

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