method

pk_and_sequence_for

v3.2.1 - Show latest stable - 0 notes - Class: ActiveRecord::ConnectionAdapters::PostgreSQLAdapter

pk_and_sequence_for(table) public

Returns a table’s primary key and belonging sequence.

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 932
      def pk_and_sequence_for(table) #:nodoc:
        # First try looking for a sequence with a dependency on the
        # given table's primary key.
        result = exec_query(          SELECT attr.attname, ns.nspname, seq.relname          FROM pg_class seq          INNER JOIN pg_depend dep ON seq.oid = dep.objid          INNER JOIN pg_attribute attr ON attr.attrelid = dep.refobjid AND attr.attnum = dep.refobjsubid          INNER JOIN pg_constraint cons ON attr.attrelid = cons.conrelid AND attr.attnum = cons.conkey[1]          INNER JOIN pg_namespace ns ON seq.relnamespace = ns.oid          WHERE seq.relkind  = 'S'            AND cons.contype = 'p'            AND dep.refobjid = '#{quote_table_name(table)}'::regclass, 'SCHEMA').rows.first

        # [primary_key, sequence]
        if result.second ==  'public' then
          sequence = result.last
        else
          sequence = result.second+'.'+result.last
        end

        [result.first, sequence]
      rescue
        nil
      end

pk_and_sequence_for

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