# Slow rendering (column statistics) after migration

**URL:** <https://www.ruby-forum.com/t/slow-rendering-column-statistics-after-migration/157016>\
**Category:** Rails\
**Created:** [January 6, 2009, 2:03pm UTC](https://www.ruby-forum.com/t/slow-rendering-column-statistics-after-migration/157016 "2009-01-06T14:03:03Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![albert](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/48db29/32.png) [@albert](https://www.ruby-forum.com/u/albert)\
**Post date:** [January 6, 2009, 2:03pm UTC](https://www.ruby-forum.com/t/slow-rendering-column-statistics-after-migration/157016/1 "2009-01-06T14:03:03Z")

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After migrating to a new system, most parts work fine and perform as  
before. But the xml template where I use column statistics performs  
very bad: 8 seconds instead of 0.2 seconds on the old system. There I  
use statements like: ‘xml.min\_resolution(satellite.sensors.minimum  
(:min\_resolution))’. Database performance is good, it is the rendering  
which takes a long time. When I remove the column statistics commands  
from the template, performance is like on the old system.

The new system is using newer versions of the system software (new/  
old): ruby 1.8.7/ruby 1.8.6, rails 2.2.2/rails 2.1.1, Linux  
2.6.18-92.el5 (both), MySQL 5.0.45 (both).

Any idea what can cause such a problem?

---

<div class="post-metadata">

**Author:** ![albert](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/48db29/32.png) [@albert](https://www.ruby-forum.com/u/albert)\
**Post date:** [January 6, 2009, 2:04pm UTC](https://www.ruby-forum.com/t/slow-rendering-column-statistics-after-migration/157016/2 "2009-01-06T14:04:50Z")

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On Jan 6, 12:55 pm, Albert [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote:

> After migrating to a new system, most parts work fine and perform as  
> before. But the xml template where I use column statistics performs  
> very bad: 8 seconds instead of 0.2 seconds on the old system. There I  
> use statements like: ‘xml.min\_resolution(satellite.sensors.minimum  
> (:min\_resolution))’. Database performance is good, it is the rendering  
> which takes a long time. When I remove the column statistics commands  
> from the template, performance is like on the old system.

I suggest you get ruby-prof and see where the time is going.

Fred