Module: PgCacheKey

Included in:
ActiveRecord::Relation
Defined in:
lib/pg_cache_key.rb,
lib/pg_cache_key/version.rb

Constant Summary collapse

VERSION = 
"0.1.8"

Instance Method Summary collapse

Instance Method Details

#cache_key_raw_sql(timestamp_column = :updated_at) ⇒ Object 



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# File 'lib/pg_cache_key.rb', line 4

def cache_key_raw_sql( timestamp_column = :updated_at )
  # Rem 1: why use connection.execute instead of doing collection.select because of an order. if you using some order on your scope
  # then columns you using to order must appear in the GROUP BY clause or be used in an aggregate function or you will get an error
  # Rem 2: we need to add select( cache_columns ) explicitly because if relation include it might transform columns to aliases
  # and we must also select them as uniq-aliase so PG wouldn't be confused
  # 'ckc' means cache key column :)
  "SELECT md5(string_agg( t.ckc_#{timestamp_column}||t.ckc_id, '') ) as cache_key FROM (#{
    select( [timestamp_column, :id].map{|ckc| "#{table_name}.#{ckc}::text as ckc_#{ckc}" } ).try(:to_sql) }) t"
end