In the SQLite Documentation it says: … “an index should be created on the child key columns of each foreign key constraint” ie. the index is not automatically created, but you should create one in every instance.
It could be correct, but that would depend on how much data you have. Typically I would create an index for the columns I was using in a GROUP BY, but in your case the optimizer may have decided that after using the field_two index that there wouldn’t be enough data returned to justify using … Read more
PostgreSQL is case sensitive. To do what you want create a function index. So say CREATE UNIQUE INDEX test_upper_idx ON mytable (UPPER(myfield)); That way when you use UPPER(myfield) in your query the index will be used. See this link
The two index options are very different. When you create a regular index on a string field it indexes the entire value in the string. Mostly useful for single word strings (like a username for logins) where you can match exactly. A text index on the other hand will tokenize and stem the content of … Read more
Yes, you can: irb(main):002:0> s1 = “foo” #=> “foo” irb(main):003:0> s2 = ObjectSpace._id2ref(s1.object_id) #=> “foo” irb(main):004:0> s2.object_id == s1.object_id #=> true irb(main):005:0> s2[0] = “z” #=> “z” irb(main):006:0> s1 #=> “zoo” Should you do this? I’ll leave that up to you. There are less geeky ways to store an object with a serializable id (e.g. … Read more
Yes, the methods can be chained. In your case you just perform the addIndex after createTable method return queryInterface.createTable(‘Todos’, { // columns… }).then(() => queryInterface.addIndex(‘Todos’, [‘author_id’, ‘title’])) .then(() => { // perform further operations if needed });
As of Django 1.5, you can use the Meta.index_together option: class QuoteModel(models.Model): # … fields … class Meta: index_together = [ (“sequence”, “stock”), ] (note: the original answer from 2009 said it was not possible to index multiple fields; it has since been replaced)
First of all, do you need to use them for text search indexing? GIN and GiST are index specialized for some data types. If you need to index simple char or integer values then the normal B-Tree index is the best. Anyway, PostgreSQL documentation has a chapter on GIST and one on GIN, where you … Read more
Use the create_index method where you pass in the keys as an array and TEXT as the index direction : collection.create_index([(‘field_i_want_to_index’, pymongo.TEXT)], name=”search_index”, default_language=”english”)
Close – you most likely want the following: add_index :person_products, [:person_id, :product_id], :unique => true add_index :person_products, :product_id The :unique => true is not strictly required and it depends whether or not it makes sense to have a person associated with a product multiple times. I would say if you’re not sure, you probably do … Read more