To expand, a better answer is when you have profiled your application and have shown a bottleneck, and have tested it with an index on that column and seen an improvement.
db_index isn't free, it incurs a penalty on writes so you need to be careful when using them. On Friday, September 16, 2011 at 12:08 AM, Micah Carrick wrote: > As an oversimplification.. any time you will be looking up a record based on > a field, then you want an index on that (or those) fields. If you're finding > a row based on a slug, you want to index that slug field. > > A good tool is to use the Django debug toolbar. When you load a page you can > take a look at the SQL queries. You can then use the 'dbshell' management > command to open up your database shell. Then you can then add "EXPLAIN " > before the SELECT queries to see how it's finding your data. Do a google > search on your database indexes and you'll find all sorts of details. > On Thu, Sep 15, 2011 at 8:38 PM, Micky Hulse <rgmi...@gmail.com > (mailto:rgmi...@gmail.com)> wrote: > > Hello, > > > > I have been using this great category/tag model: > > > > https://github.com/praekelt/django-category/blob/master/category/models.py > > > > ... and I noticed that the author added a db_index on the SlugField of > > the Category model. > > > > I hate to admit it, but I don't think I have ever explicitly used > > db_index parameter on any of my models. > > > > When's a good time to use db_index? Is there a general rule of thumb > > when coding Django models? > > > > Sorry if silly question. > > > > Thanks so much! > > > > Cheers, > > Micky > > > > -- > > You received this message because you are subscribed to the Google Groups > > "Django users" group. > > To post to this group, send email to django-users@googlegroups.com > > (mailto:django-users@googlegroups.com). > > To unsubscribe from this group, send email to > > django-users+unsubscr...@googlegroups.com > > (mailto:django-users%2bunsubscr...@googlegroups.com). > > For more options, visit this group at > > http://groups.google.com/group/django-users?hl=en. > > > > -- > You received this message because you are subscribed to the Google Groups > "Django users" group. > To post to this group, send email to django-users@googlegroups.com > (mailto:django-users@googlegroups.com). > To unsubscribe from this group, send email to > django-users+unsubscr...@googlegroups.com > (mailto:django-users+unsubscr...@googlegroups.com). > For more options, visit this group at > http://groups.google.com/group/django-users?hl=en. -- You received this message because you are subscribed to the Google Groups "Django users" group. To post to this group, send email to django-users@googlegroups.com. To unsubscribe from this group, send email to django-users+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/django-users?hl=en.
