add_index(table_name, column_name, options = {}) — ActiveRecord::ConnectionAdapters::SchemaStatements

add_index(table_name, column_name, options = {})

Adds a new index to the table. column_name can be a single Symbol, or an Array of Symbols.

The index will be named after the table and the first column name, unless you pass :name as an option.

When creating an index on multiple columns, the first column is used as a name for the index. For example, when you specify an index on two columns [:first, :last], the DBMS creates an index for both columns as well as an index for the first column :first. Using just the first name for this index makes sense, because you will never have to create a singular index with this name.

Examples

Creating a simple index

add_index(:suppliers, :name)

generates

CREATE INDEX suppliers_name_index ON suppliers(name)

Creating a unique index

add_index(:accounts, [:branch_id, :party_id], :unique => true)

generates

CREATE UNIQUE INDEX accounts_branch_id_party_id_index ON accounts(branch_id, party_id)

Creating a named index

add_index(:accounts, [:branch_id, :party_id], :unique => true, :name => 'by_branch_party')

generates

CREATE UNIQUE INDEX by_branch_party ON accounts(branch_id, party_id)

Parameters

table_name req
column_name req
options opt = {}

Source

# File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 261
      def add_index(table_name, column_name, options = {})
        column_names = Array(column_name)
        index_name   = index_name(table_name, :column => column_names)

        if Hash === options # legacy support, since this param was a string
          index_type = options[:unique] ? "UNIQUE" : ""
          index_name = options[:name] || index_name
        else
          index_type = options
        end
        quoted_column_names = column_names.map { |e| quote_column_name(e) }.join(", ")
        execute "CREATE #{index_type} INDEX #{quote_column_name(index_name)} ON #{quote_table_name(table_name)} (#{quoted_column_names})"
      end

Defined in activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb line 261 · View on GitHub · Improve this page · Find usages on GitHub

Defined in ActiveRecord::ConnectionAdapters::SchemaStatements

Signature

Examples

Creating a simple index

Creating a unique index

Creating a named index

Parameters