Ruby Mysql2: different results using count method

Question

I'm using .count method in a mysql2 query results:

My code:

  require "mysql2"

  hostname='db.xxxxx.xxx'
  port='3306'
  username='xxxxxx'
  password='xxxxxxxxxxxxxxxxxxxxxxxxxx'
  database='xxx'

  dbh = Mysql2::Client.new(:host=> hostname, :username=> username, :password=> password, :database=> database, :port=> port.to_f, :database_timezone=> :utc, :application_timezone => :local)


  results=dbh.query("SELECT * FROM xxx")
    p results.count
    i=0
    results.each do |result|
        i=i+1   
    end

    p results.count

With the first results.count I obtain the number of SELECT results rows as expected. But for the second one, I obtain (sometimes!) a different value:

My results:

$ ruby test_count.rb
4942
4942

$ ruby test_count.rb 
4942
24773520

$ ruby test_count.rb 
4942
37442208

My config:

$ rvm --version
rvm 1.13.4 (stable) by Wayne E. Seguin <wayneeseguin@gmail.com>, Michal Papis <mpapis@gmail.com> [https://rvm.io/]

$ ruby --version
ruby 1.9.3p194 (2012-04-20 revision 35410) [x86_64-linux]

$ gem list

*** LOCAL GEMS ***

Ascii85 (1.0.1)
bundler (1.1.3)
curb (0.8.0)
mime-types (1.18)
mysql (2.8.1)
mysql2 (0.3.11)
pdf-reader (1.1.1)
prawn (0.12.0)
prawn-core (0.8.4)
rake (0.9.2.2)
ruby-filemagic (0.4.2)
ruby-rc4 (0.1.5)
rubygems-bundler (0.9.2)
RubyInline (3.11.2)
rvm (1.11.3.3)
ttfunk (1.0.3)
ZenTest (4.8.0)

Someone have any idea why is this happen?

Thanks

Sounds like result is being modified. Can you post the actual code? What you posted is syntactically invalid. — d11wtq, Jun 11 '12 at 00:47
Thanks, I have updated my code. Runing this code give me the same results, sometimes I have the good answer, sometimes a big integer — user1447891, Jun 11 '12 at 17:39

score 0 · Answer 1 · answered Jun 11 '12 at 03:14

Check your = versus ==. Also, the first results is an array. If you change to a string by doing some sort of .to_s or join and putting it back in the same variable, eg, results = results.join, then length would change. If you add elements to the array by mistake using results += results + another_array, then your count will increas fast. Best is to post your real code here. I know because I have done some of these at one time or another.

Ruby Mysql2: different results using count method

1 Answers1