Rails Postgres functional indexes

Question

How I should enter my multicolum indexes which contain functions into schema.rb ?

for example this DOESN'T work:

add_index "temporary_events", ["templateinfoid", "campaign", "date(gw_out_time)", "messagetype"], :name => "temporary_events_campaign_tinfoid_date_messagetype"

rake db:test:load

rake aborted!

PGError: ERROR: column "date(gw_out_time)" does not exist

: CREATE INDEX "temporary_events_campaign_tinfoid_date_messagetype" ON "temporary_events" ("templateinfoid", "campaign", "date(gw_out_time", "messagetype")

Answer 1

The built-in ActiveRecord method for creating indexes (add_index) does not support functions or any other more advanced features. Instead you can use execute to create the index with SQL:

execute <<-SQL
  CREATE INDEX temporary_events_campaign_tinfoid_date_messagetype
  ON temporary_events(templateinfoid, campaign", date(gw_out_time), messagetype);
SQL

Note that the use of execute in migrations can be problematic if you are not using the SQL schema format (config.active_record.schema_format = :sql). For more information, search for schema_format.