# Pseudo array for Rails migration **URL:** \ **Category:** Ruby\ **Created:** [November 22, 2009, 3:06pm UTC](https://www.ruby-forum.com/t/pseudo-array-for-rails-migration/179335 "2009-11-22T15:06:34Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![ralphshnelvar](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/e19adc/32.png) [@ralphshnelvar](https://www.ruby-forum.com/u/ralphshnelvar)\ **Post date:** [November 22, 2009, 3:06pm UTC](https://www.ruby-forum.com/t/pseudo-array-for-rails-migration/179335/1 "2009-11-22T15:06:34Z")
Consider N\_X = 20 # size of pseudo array class CreatePeople \< ActiveRecord::Migration ``` create_table :people do |t| t.string :first_name , :null => false . . . t.integer :x00 t.integer :x01 t.integer :x02 . . . t.integer :x18 t.integer :x19 t.timestamps end ``` end What is the (best) way of generating the “t.integer :xYY” (where YY is 00 through 19, inclusive) which is dependent on N\_X. ---
**Author:** ![ralphshnelvar](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/e19adc/32.png) [@ralphshnelvar](https://www.ruby-forum.com/u/ralphshnelvar)\ **Post date:** [November 22, 2009, 3:57pm UTC](https://www.ruby-forum.com/t/pseudo-array-for-rails-migration/179335/2 "2009-11-22T15:57:29Z")
On 22.11.2009 15:06, Ralph S. wrote: > ``` > . > > t.timestamps > end > > ``` > > end > > What is the (best) way of generating the “t.integer :xYY” (where YY is > 00 through 19, inclusive) which is dependent on N\_X. What stops you from doing N\_X = 20 # size of pseudo array class CreatePeople \< ActiveRecord::Migration ``` create_table :people do |t| t.string :first_name , :null => false . . . N_X.times do |i| t.integer(("x%02d" % i).to_sym) end t.timestamps end ``` end ? Btw, having columns with indexes in their name is considered bad schema design because you either could normalize it into another table and join or provide more meaningful names instead of “x02” if it is used as a placeholder. My 0.02EUR. Kind regards robert ---
**Author:** ![ralphshnelvar](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/e19adc/32.png) [@ralphshnelvar](https://www.ruby-forum.com/u/ralphshnelvar)\ **Post date:** [November 22, 2009, 4:22pm UTC](https://www.ruby-forum.com/t/pseudo-array-for-rails-migration/179335/3 "2009-11-22T16:22:39Z")
RK\> On 22.11.2009 15:06, Ralph S. wrote: > > ``` > > . > > > > t.timestamps > > end > > > > ``` > > > > end > > > > What is the (best) way of generating the “t.integer :xYY” (where YY is > > 00 through 19, inclusive) which is dependent on N\_X. RK\> What stops you from doing RK\> N\_X = 20 # size of pseudo array RK\> class CreatePeople \< ActiveRecord::Migration RK\> create\_table :people do |t| RK\> t.string :first\_name , :null =\> false RK\> . RK\> . RK\> . RK\> N\_X.times do |i| RK\> t.integer((“x%02d” % i).to\_sym) RK\> end RK\> t.timestamps RK\> end RK\> end RK\> ? Btw, having columns with indexes in their name is considered bad RK\> schema design because you either could normalize it into another table RK\> and join or provide more meaningful names instead of “x02” if it is used RK\> as a placeholder. My 0.02EUR. RK\> Kind regards First of all, I’m a noob. I should have said that. Thus your solution (1) Makes sense. (2) Explains a lot about Ruby. For both I thank you. In terms of normalizing the database, I ran some timing tests and normalizing it slows me down a couple of orders of magnitude. I’m willing to live with the lack of purity for the sake of performance. ---
**Author:** ![ralphshnelvar](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/e19adc/32.png) [@ralphshnelvar](https://www.ruby-forum.com/u/ralphshnelvar)\ **Post date:** [November 25, 2009, 6:35pm UTC](https://www.ruby-forum.com/t/pseudo-array-for-rails-migration/179335/4 "2009-11-25T18:35:23Z")
On 22.11.2009 17:05, Marnen Laibow-Koser wrote: > > normalizing it slows me down a couple of orders of magnitude. I’m > > willing to live with the lack of purity for the sake of performance. > > A couple orders of magnitude? This suggests to me that your > normalization and/or queries are poorly done. What is chewing up so > much time, and what does the normalized schema look like? It should be > possible to find a solution that performs reasonably and doesn’t have 20 > repeating fields. I second that. Ralph, any information about the slowness? Is it in the database or outside? Kind regards robert ---
**Author:** ![ralphshnelvar](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/e19adc/32.png) [@ralphshnelvar](https://www.ruby-forum.com/u/ralphshnelvar)\ **Post date:** [November 22, 2009, 5:05pm UTC](https://www.ruby-forum.com/t/pseudo-array-for-rails-migration/179335/5 "2009-11-22T17:05:23Z")
Ralph S. wrote: […] > RK\> ? Btw, having columns with indexes in their name is considered bad > RK\> schema design because you either could normalize it into another > table > RK\> and join or provide more meaningful names instead of “x02” if it is > used > RK\> as a placeholder. My 0.02EUR. > > RK\> Kind regards > > First of all, I’m a noob. I should have said that. > > Thus your solution > (1) Makes sense. > (2) Explains a lot about Ruby. > > For both I thank you. > > In terms of normalizing the database, I ran some timing tests and > normalizing it slows me down a couple of orders of magnitude. I’m > willing to live with the lack of purity for the sake of performance. A couple orders of magnitude? This suggests to me that your normalization and/or queries are poorly done. What is chewing up so much time, and what does the normalized schema look like? It should be possible to find a solution that performs reasonably and doesn’t have 20 repeating fields. ## Best, Marnen Laibow-Koser [http://www.marnen.org](http://www.marnen.org) removed\_email\_address@domain.invalid ---
**Author:** ![ralphshnelvar](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/e19adc/32.png) [@ralphshnelvar](https://www.ruby-forum.com/u/ralphshnelvar)\ **Post date:** [November 25, 2009, 7:05pm UTC](https://www.ruby-forum.com/t/pseudo-array-for-rails-migration/179335/6 "2009-11-25T19:05:50Z")
Wednesday, November 25, 2009, 10:35:06 AM, you wrote: RK\> On 22.11.2009 17:05, Marnen Laibow-Koser wrote: > > > normalizing it slows me down a couple of orders of magnitude. I’m > > > willing to live with the lack of purity for the sake of performance. > > > > A couple orders of magnitude? This suggests to me that your > > normalization and/or queries are poorly done. What is chewing up so > > much time, and what does the normalized schema look like? It should be > > possible to find a solution that performs reasonably and doesn’t have 20 > > repeating fields. RK\> I second that. Ralph, any information about the slowness? Is it in the RK\> database or outside? I _think_ it is, in part, coming from the logging that is being done. Instead of one create … one can have 21. ---
**Author:** ![ralphshnelvar](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/e19adc/32.png) [@ralphshnelvar](https://www.ruby-forum.com/u/ralphshnelvar)\ **Post date:** [November 25, 2009, 9:42pm UTC](https://www.ruby-forum.com/t/pseudo-array-for-rails-migration/179335/7 "2009-11-25T21:42:29Z")
Ralph S. wrote: > Wednesday, November 25, 2009, 10:35:06 AM, you wrote: > > RK\> On 22.11.2009 17:05, Marnen Laibow-Koser wrote: > > > > > normalizing it slows me down a couple of orders of magnitude. I’m > > > > willing to live with the lack of purity for the sake of performance. > > > > > > A couple orders of magnitude? This suggests to me that your > > > normalization and/or queries are poorly done. What is chewing up so > > > much time, and what does the normalized schema look like? It should be > > > possible to find a solution that performs reasonably and doesn’t have 20 > > > repeating fields. > > RK\> I second that. Ralph, any information about the slowness? Is it in > the > RK\> database or outside? > > I _think_ it is, in part, coming from the logging that is being done. > > Instead of one create … one can have 21. Then, as I suspected, you are using the DB incorrectly. To create 21 records, use 1 query, not 21. You can use ar-extensions or something similar to do this with ActiveRecord. Rule of thumb: queries don’t belong inside loops. If you find yourself putting a query in a loop, you have a design problem. ## Best, Marnen Laibow-Koser [http://www.marnen.org](http://www.marnen.org) removed\_email\_address@domain.invalid