Top "Database-indexes" questions

How to implement composite primary keys in rails

I have a User model that looks like this: class User < ApplicationRecord belongs_to :organization belongs_to :department end …

ruby-on-rails ruby database ruby-on-rails-5 database-indexes

On Duplicate Update does not work for unique index

My SQL Table I am trying to insert/update has this definition: CREATE TABLE `place`.`a_table` ( `id` bigint(20) NOT …

mysql database-indexes

How binary search is used in database indexing

I know how binary search works but I wanted to know practical uses for binary search... I searched through the …

database algorithm relational-database binary-search database-indexes

Oracle - Create an index only if not exists

Is there any way to create indexes in oracle only if they don't exists ? Something like CREATE INDEX IF NOT …

oracle database-indexes

Whether SQL query will work if there are no indexes on the relations?

GATE1999_2.25 Which of the following is/are correct? A) An SQL query automatically eliminates duplicates B) An SQL query will …

sql database-indexes

MySQL Optimization: EXPLAIN "Extra" column contains "Using Where"

So I always thought that seeing "Using Where" in the Extra column was a good thing. However, I was planning …

mysql database-optimization database-indexes

Why would MySQL use index intersection instead of combined index?

From time to time I encounter a strange MySQL behavior. Let's assume I have indexes (type, rel, created), (type), (rel). …

mysql query-optimization sql-execution-plan database-indexes

Django: Does unique_together imply db_index=True in the same way that ForeignKey does?

A field on a model, foo = models.ForeignKey(Foo) will automatically add a database index for the column, in order …

python django django-models database-indexes