Contents

module ::ArJdbc
  module SQLite3
    module ExplainSupport
      def supports_explain?
        true
      end

      def explain(arel, binds = [])
        sql = "EXPLAIN QUERY PLAN #{to_sql(arel, binds)}"
        result  = exec_query(sql, "EXPLAIN", binds)
        ExplainPrettyPrinter.new.pp result
      end

      class ExplainPrettyPrinter # :nodoc:
        # Pretty prints the result of a EXPLAIN QUERY PLAN in a way that resembles
        # the output of the SQLite shell:
        #
        # 0|0|0|SEARCH TABLE users USING INTEGER PRIMARY KEY (rowid=?) (~1 rows)
        # 0|1|1|SCAN TABLE posts (~100000 rows)
        #
        def pp(result)
          result.rows.map do |row|
            row.join('|')
          end.join("\n") + "\n"
        end
      end
    end
  end
end

Version data entries

2 entries across 2 versions & 1 rubygems

Version	Path
activerecord-jdbc-adapter-1.3.0.beta2	lib/arjdbc/sqlite3/explain_support.rb
activerecord-jdbc-adapter-1.3.0.beta1	lib/arjdbc/sqlite3/explain_support.rb